<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:c54bb9fe-5fe3-484c-8c37-1247bde19e06,g:0a179766-9174-4357-afdf-29ab18a19ddc-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/ConsolidatedStatementsofOperations" xlink:type="simple" xlink:href="ebs-20231231.xsd#ConsolidatedStatementsofOperations"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/ConsolidatedStatementsofOperations" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_f9865ccf-bf5a-4836-9914-64d7a3930d93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_StatementTable_f9865ccf-bf5a-4836-9914-64d7a3930d93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_31a11f36-1a30-4a03-af52-3f441dd22d5e" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_f9865ccf-bf5a-4836-9914-64d7a3930d93" xlink:to="loc_srt_ProductOrServiceAxis_31a11f36-1a30-4a03-af52-3f441dd22d5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_31a11f36-1a30-4a03-af52-3f441dd22d5e_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_31a11f36-1a30-4a03-af52-3f441dd22d5e" xlink:to="loc_srt_ProductsAndServicesDomain_31a11f36-1a30-4a03-af52-3f441dd22d5e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_00df085b-067f-4985-83a5-42685318bff1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_31a11f36-1a30-4a03-af52-3f441dd22d5e" xlink:to="loc_srt_ProductsAndServicesDomain_00df085b-067f-4985-83a5-42685318bff1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_82497249-311d-41aa-a8ed-62816189adb1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_00df085b-067f-4985-83a5-42685318bff1" xlink:to="loc_us-gaap_ProductMember_82497249-311d-41aa-a8ed-62816189adb1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductMember_3a34b994-a3d9-4df7-b621-5505cb789e19" xlink:href="ebs-20231231.xsd#ebs_CommercialProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_82497249-311d-41aa-a8ed-62816189adb1" xlink:to="loc_ebs_CommercialProductMember_3a34b994-a3d9-4df7-b621-5505cb789e19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MedicalCountermeasuresMCMProductMember_186dd1de-81dd-4bb8-90e6-e7601136e794" xlink:href="ebs-20231231.xsd#ebs_MedicalCountermeasuresMCMProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_82497249-311d-41aa-a8ed-62816189adb1" xlink:to="loc_ebs_MedicalCountermeasuresMCMProductMember_186dd1de-81dd-4bb8-90e6-e7601136e794" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesMember_abe98f76-f8f9-4a38-8b8f-4abe6d591017" xlink:href="ebs-20231231.xsd#ebs_BioservicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_00df085b-067f-4985-83a5-42685318bff1" xlink:to="loc_ebs_BioservicesMember_abe98f76-f8f9-4a38-8b8f-4abe6d591017" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_bdd905da-d43c-42d6-91a9-32c34a0bb254" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_BioservicesMember_abe98f76-f8f9-4a38-8b8f-4abe6d591017" xlink:to="loc_us-gaap_ServiceMember_bdd905da-d43c-42d6-91a9-32c34a0bb254" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesLeasesMember_e82ea999-92fa-4e3b-91d0-686f9664390f" xlink:href="ebs-20231231.xsd#ebs_BioservicesLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_BioservicesMember_abe98f76-f8f9-4a38-8b8f-4abe6d591017" xlink:to="loc_ebs_BioservicesLeasesMember_e82ea999-92fa-4e3b-91d0-686f9664390f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ContractsAndGrantsMember_5d184b51-bd6e-461a-97ca-fd87ccbb1171" xlink:href="ebs-20231231.xsd#ebs_ContractsAndGrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_00df085b-067f-4985-83a5-42685318bff1" xlink:to="loc_ebs_ContractsAndGrantsMember_5d184b51-bd6e-461a-97ca-fd87ccbb1171" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_afe0b80e-a6bb-4e35-b6c2-b12ab316dc94" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_afe0b80e-a6bb-4e35-b6c2-b12ab316dc94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_018fbf96-e259-4fb5-b51d-559f5897a091" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_018fbf96-e259-4fb5-b51d-559f5897a091" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_d21c95d2-f1e9-48e0-b7dc-23a38e4c3ab4" xlink:href="ebs-20231231.xsd#ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:to="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_d21c95d2-f1e9-48e0-b7dc-23a38e4c3ab4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_57c9c973-ab90-4034-94e3-035ce000be7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_e2816070-3750-4b87-a6f8-ac43478959cf" xlink:to="loc_us-gaap_Revenues_57c9c973-ab90-4034-94e3-035ce000be7c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_2f3a5f31-b4f3-4aa1-b14f-b41664bb226e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_2f3a5f31-b4f3-4aa1-b14f-b41664bb226e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_b5192a54-9095-4613-89c2-06c849c47419" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_b5192a54-9095-4613-89c2-06c849c47419" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_3f11889f-e028-4f3c-bff4-7b8be131e3ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_3f11889f-e028-4f3c-bff4-7b8be131e3ba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_04c08a58-0c74-450d-973e-9445cea8a3e0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_04c08a58-0c74-450d-973e-9445cea8a3e0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_a5fb48f3-14fd-469c-b135-3a007b6d86bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_a5fb48f3-14fd-469c-b135-3a007b6d86bf" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_a695da48-5c7f-4e50-aa94-f1e12be7049a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_a695da48-5c7f-4e50-aa94-f1e12be7049a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingCostsAndExpenses_1a6080ea-2ca3-4016-9fc2-983a6e6ada5b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingCostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_d31742ce-f3eb-4509-a227-2b61c407e8f0" xlink:to="loc_us-gaap_OperatingCostsAndExpenses_1a6080ea-2ca3-4016-9fc2-983a6e6ada5b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_78078a8c-fd96-43e8-b689-83a34f40147e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_OperatingIncomeLoss_78078a8c-fd96-43e8-b689-83a34f40147e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_76f4d290-119b-4a4b-a76b-d76b0220b419" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:to="loc_us-gaap_InterestExpense_76f4d290-119b-4a4b-a76b-d76b0220b419" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_198ee681-2e27-429c-930f-de1fc626d3a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_198ee681-2e27-429c-930f-de1fc626d3a1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_7ba79f19-159e-4ea0-b725-ad4602c45f19" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_7ba79f19-159e-4ea0-b725-ad4602c45f19" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_249b9a2e-b246-4401-b8b1-c40e6d2da83d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NonoperatingIncomeExpenseAbstract_f3913fef-3110-4442-a3e4-494c79aebab3" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_249b9a2e-b246-4401-b8b1-c40e6d2da83d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7e1d22c1-cb4e-4821-875a-a0a343c4f33f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_7e1d22c1-cb4e-4821-875a-a0a343c4f33f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_27e2eb7a-d07f-4026-8b9e-4dab1ff7ba1c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_27e2eb7a-d07f-4026-8b9e-4dab1ff7ba1c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_68977af1-065b-4305-ab06-da7332963c99" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_NetIncomeLoss_68977af1-065b-4305-ab06-da7332963c99" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_df7efb71-005e-4290-811e-1ae0f6f5cf34" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_df7efb71-005e-4290-811e-1ae0f6f5cf34" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_35f715c1-7679-4bde-a09f-6d56cc899683" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_df7efb71-005e-4290-811e-1ae0f6f5cf34" xlink:to="loc_us-gaap_EarningsPerShareBasic_35f715c1-7679-4bde-a09f-6d56cc899683" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_db986aa2-71cb-4949-8513-38efd4d378f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_df7efb71-005e-4290-811e-1ae0f6f5cf34" xlink:to="loc_us-gaap_EarningsPerShareDiluted_db986aa2-71cb-4949-8513-38efd4d378f4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_7ae85dd9-dfb8-4f34-8c93-5e9f8b5a6e3b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_06ea529b-508f-4a25-9a0c-e3f3e600f824" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_7ae85dd9-dfb8-4f34-8c93-5e9f8b5a6e3b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_d634c445-84b9-43ae-997e-51858fa49760" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_7ae85dd9-dfb8-4f34-8c93-5e9f8b5a6e3b" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_d634c445-84b9-43ae-997e-51858fa49760" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_8182797a-13c8-4b24-bd82-03ecc7c60837" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_7ae85dd9-dfb8-4f34-8c93-5e9f8b5a6e3b" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_8182797a-13c8-4b24-bd82-03ecc7c60837" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/ConsolidatedStatementofChangesinStockholdersEquity" xlink:type="simple" xlink:href="ebs-20231231.xsd#ConsolidatedStatementofChangesinStockholdersEquity"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/ConsolidatedStatementofChangesinStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_0c8f3da6-7274-4353-a89e-ad4db1f2dd6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_da4a8489-4ff8-4622-b916-3a4b70444d38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_0c8f3da6-7274-4353-a89e-ad4db1f2dd6e" xlink:to="loc_us-gaap_StatementTable_da4a8489-4ff8-4622-b916-3a4b70444d38" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_47ed20bd-e0e7-4897-8bea-2d61352dc54c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_da4a8489-4ff8-4622-b916-3a4b70444d38" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_47ed20bd-e0e7-4897-8bea-2d61352dc54c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_47ed20bd-e0e7-4897-8bea-2d61352dc54c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_47ed20bd-e0e7-4897-8bea-2d61352dc54c" xlink:to="loc_us-gaap_EquityComponentDomain_47ed20bd-e0e7-4897-8bea-2d61352dc54c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_47ed20bd-e0e7-4897-8bea-2d61352dc54c" xlink:to="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_773b5098-68b4-4e49-9491-7065adf2cdf1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:to="loc_us-gaap_CommonStockMember_773b5098-68b4-4e49-9491-7065adf2cdf1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_048cbd3a-1b68-45d8-b3ad-99d4d391408a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_048cbd3a-1b68-45d8-b3ad-99d4d391408a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_b81fec46-1e7a-4d66-a31a-f936a671dd01" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:to="loc_us-gaap_TreasuryStockCommonMember_b81fec46-1e7a-4d66-a31a-f936a671dd01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_8491011d-b565-41a4-895e-5b968dcc0b83" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_8491011d-b565-41a4-895e-5b968dcc0b83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_4a54bf9d-1c11-4cbc-bbcc-2ec494bfc1c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_09bf6b52-4075-4695-a60c-8065ffc88ead" xlink:to="loc_us-gaap_RetainedEarningsMember_4a54bf9d-1c11-4cbc-bbcc-2ec494bfc1c9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_0c8f3da6-7274-4353-a89e-ad4db1f2dd6e" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_a5a1370f-2981-46b4-b158-3d2999f67655" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_CommonStockSharesIssued_a5a1370f-2981-46b4-b158-3d2999f67655" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_a7459275-4584-42bf-a098-807a279f101f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockholdersEquity_a7459275-4584-42bf-a098-807a279f101f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_cca757e1-4bba-4244-b3ae-f397dbeec619" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_TreasuryStockCommonShares_cca757e1-4bba-4244-b3ae-f397dbeec619" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_2d66e952-5da4-423e-b38f-a8a7aa3ae599" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_NetIncomeLoss_2d66e952-5da4-423e-b38f-a8a7aa3ae599" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_9295f503-ebd8-4ac3-ad2c-46af3e5c41eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_9295f503-ebd8-4ac3-ad2c-46af3e5c41eb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_e252bdaa-a80b-4974-a091-d648d9060291" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_e252bdaa-a80b-4974-a091-d648d9060291" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_508dff15-5c07-48e6-85bf-f477d64a12a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_508dff15-5c07-48e6-85bf-f477d64a12a9" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_82d3c191-6977-4c99-8caa-394204200e84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_82d3c191-6977-4c99-8caa-394204200e84" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_19726329-96c5-4615-8740-d13377d2d3ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_19726329-96c5-4615-8740-d13377d2d3ac" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_eec202ec-8227-4443-b2f4-4ee9b5c94608" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesNewIssues_eec202ec-8227-4443-b2f4-4ee9b5c94608" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6ff2b965-220f-4515-98a0-bd99fc0f6cc0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_24718c7b-1ffa-4ec8-97e5-0b09c5e55224" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueNewIssues_6ff2b965-220f-4515-98a0-bd99fc0f6cc0" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesIssued_50f149ed-9e00-406d-9dd0-5aa194230d18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesIssued"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_2c6f19db-0aae-4ac7-8f4a-a286c4ba1a16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonShares_958000ed-948f-4ccf-9df4-6f9ece636671" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonShares"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesGoingConcernDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SummaryofsignificantaccountingpoliciesGoingConcernDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesGoingConcernDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_77595c44-e4d3-4848-9030-c24ddf7d0126" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_bfe73d37-cc7e-4dc8-a4aa-7495a3bb866e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_77595c44-e4d3-4848-9030-c24ddf7d0126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_474d9ee5-5bed-43cb-826f-575788baaa54" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_77595c44-e4d3-4848-9030-c24ddf7d0126" xlink:to="loc_us-gaap_LineOfCreditMember_474d9ee5-5bed-43cb-826f-575788baaa54" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_ad6ebbec-90f1-4a22-9dab-f8ee8cebf96e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_77595c44-e4d3-4848-9030-c24ddf7d0126" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_ad6ebbec-90f1-4a22-9dab-f8ee8cebf96e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_a36da7d2-50f2-401c-8a65-0dc5e867b914" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_77595c44-e4d3-4848-9030-c24ddf7d0126" xlink:to="loc_us-gaap_SeniorNotesMember_a36da7d2-50f2-401c-8a65-0dc5e867b914" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_5d7ddbf6-372b-4d92-af34-73cd1da15b29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:to="loc_us-gaap_CreditFacilityAxis_5d7ddbf6-372b-4d92-af34-73cd1da15b29" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_5d7ddbf6-372b-4d92-af34-73cd1da15b29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_5d7ddbf6-372b-4d92-af34-73cd1da15b29" xlink:to="loc_us-gaap_CreditFacilityDomain_5d7ddbf6-372b-4d92-af34-73cd1da15b29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_c112a660-70ab-4b5b-a946-65ad6bc755e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_5d7ddbf6-372b-4d92-af34-73cd1da15b29" xlink:to="loc_us-gaap_CreditFacilityDomain_c112a660-70ab-4b5b-a946-65ad6bc755e3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2b0a476b-ebef-43f6-ba89-691dbad8a929" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_c112a660-70ab-4b5b-a946-65ad6bc755e3" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2b0a476b-ebef-43f6-ba89-691dbad8a929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_TermLoanFacilityMember_a409706c-f0bc-4820-a4ff-829c2507afea" xlink:href="ebs-20231231.xsd#ebs_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_c112a660-70ab-4b5b-a946-65ad6bc755e3" xlink:to="loc_ebs_TermLoanFacilityMember_a409706c-f0bc-4820-a4ff-829c2507afea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_74090736-6d62-454e-8462-5d5c011c494f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:to="loc_us-gaap_DebtInstrumentAxis_74090736-6d62-454e-8462-5d5c011c494f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_74090736-6d62-454e-8462-5d5c011c494f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_74090736-6d62-454e-8462-5d5c011c494f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_74090736-6d62-454e-8462-5d5c011c494f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_df692c9b-b42d-4332-92df-b2821a5ecca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_74090736-6d62-454e-8462-5d5c011c494f" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_df692c9b-b42d-4332-92df-b2821a5ecca5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AmendedCreditAgreementMember_323b3c03-6995-4c89-a067-0bd689ee95d1" xlink:href="ebs-20231231.xsd#ebs_AmendedCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_df692c9b-b42d-4332-92df-b2821a5ecca5" xlink:to="loc_ebs_AmendedCreditAgreementMember_323b3c03-6995-4c89-a067-0bd689ee95d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_f44d6218-bd99-42bc-9efc-66dde36d2d4c" xlink:href="ebs-20231231.xsd#ebs_SeniorUnsecuredNotesDueAugust2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_df692c9b-b42d-4332-92df-b2821a5ecca5" xlink:to="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_f44d6218-bd99-42bc-9efc-66dde36d2d4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_a8f72ddb-4cbe-4fe6-baed-efeb3815b067" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_3afa9395-5b48-4289-bbad-384e687a5024" xlink:to="loc_us-gaap_RestructuringPlanAxis_a8f72ddb-4cbe-4fe6-baed-efeb3815b067" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_a8f72ddb-4cbe-4fe6-baed-efeb3815b067_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_a8f72ddb-4cbe-4fe6-baed-efeb3815b067" xlink:to="loc_us-gaap_RestructuringPlanDomain_a8f72ddb-4cbe-4fe6-baed-efeb3815b067_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_33be5009-e1c0-4858-a7df-83ceb6860f97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_a8f72ddb-4cbe-4fe6-baed-efeb3815b067" xlink:to="loc_us-gaap_RestructuringPlanDomain_33be5009-e1c0-4858-a7df-83ceb6860f97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanJanuary2023Member_ab192c1f-1249-4524-9559-2d5233457b94" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanJanuary2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_33be5009-e1c0-4858-a7df-83ceb6860f97" xlink:to="loc_ebs_RestructuringPlanJanuary2023Member_ab192c1f-1249-4524-9559-2d5233457b94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanAugust2023Member_9f7072d4-7adb-475b-a817-db03da76d0e2" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanAugust2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_33be5009-e1c0-4858-a7df-83ceb6860f97" xlink:to="loc_ebs_RestructuringPlanAugust2023Member_9f7072d4-7adb-475b-a817-db03da76d0e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_b4a077ab-436c-4899-b201-79e238351f5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_LongTermDebt_b4a077ab-436c-4899-b201-79e238351f5d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_7c2cda4b-544e-4b83-a73b-4b04219179d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_7c2cda4b-544e-4b83-a73b-4b04219179d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentCovenantConsiderationThreshold_0ba47a82-b87c-4fba-8b41-a7b278f53db0" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentCovenantConsiderationThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_ebs_DebtInstrumentCovenantConsiderationThreshold_0ba47a82-b87c-4fba-8b41-a7b278f53db0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_8281bb67-2a65-4e64-a11f-72db7744af5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_8281bb67-2a65-4e64-a11f-72db7744af5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_d55bb392-2c92-43db-93b5-6c4a4999da97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_LineOfCredit_d55bb392-2c92-43db-93b5-6c4a4999da97" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_b1d82739-ce3f-486c-b455-68d588bf4239" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_b1d82739-ce3f-486c-b455-68d588bf4239" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_83bd84f7-cc32-468d-b8ce-71d1e0bb6b16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_82da8883-87be-4f07-8b23-77bed52fa527" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_83bd84f7-cc32-468d-b8ce-71d1e0bb6b16" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesConcentrationRiskDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SummaryofsignificantaccountingpoliciesConcentrationRiskDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesConcentrationRiskDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_0b4187c8-e987-4bf2-be83-c0bfdfdc1978" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_dd09511a-9e62-4ac7-a5d5-14b0ec46f10d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_0b4187c8-e987-4bf2-be83-c0bfdfdc1978" xlink:to="loc_us-gaap_ConcentrationRiskTable_dd09511a-9e62-4ac7-a5d5-14b0ec46f10d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_dd09511a-9e62-4ac7-a5d5-14b0ec46f10d" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_77d818d1-a1cd-495a-80c9-36c893f81f2c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_168b0970-90d2-4df9-bcff-b7fe8ae5c8e4" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_77d818d1-a1cd-495a-80c9-36c893f81f2c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_364295ae-5876-4203-8c52-40f30917306a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_77d818d1-a1cd-495a-80c9-36c893f81f2c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_364295ae-5876-4203-8c52-40f30917306a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_67676fcb-814a-4b13-bd5d-d98b4ab0e41f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_dd09511a-9e62-4ac7-a5d5-14b0ec46f10d" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_67676fcb-814a-4b13-bd5d-d98b4ab0e41f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_67676fcb-814a-4b13-bd5d-d98b4ab0e41f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_67676fcb-814a-4b13-bd5d-d98b4ab0e41f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_67676fcb-814a-4b13-bd5d-d98b4ab0e41f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_d766df16-6e7a-4808-ad84-913f16a59c09" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_67676fcb-814a-4b13-bd5d-d98b4ab0e41f" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_d766df16-6e7a-4808-ad84-913f16a59c09" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_56acd602-57bc-41ed-a248-f7227114d7a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_d766df16-6e7a-4808-ad84-913f16a59c09" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_56acd602-57bc-41ed-a248-f7227114d7a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_dd09511a-9e62-4ac7-a5d5-14b0ec46f10d" xlink:to="loc_srt_MajorCustomersAxis_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4" xlink:to="loc_srt_NameOfMajorCustomerDomain_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_9128716f-815f-4171-bd38-4807d76ac75a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_e29f4b29-94b3-43e1-8f66-6e390ad5ddf4" xlink:to="loc_srt_NameOfMajorCustomerDomain_9128716f-815f-4171-bd38-4807d76ac75a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnitedStatesGovernmentMember_596c56ee-23c9-4a65-be14-08dcfbd88334" xlink:href="ebs-20231231.xsd#ebs_UnitedStatesGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_9128716f-815f-4171-bd38-4807d76ac75a" xlink:to="loc_ebs_UnitedStatesGovernmentMember_596c56ee-23c9-4a65-be14-08dcfbd88334" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_893ac02f-fb84-4149-b0ef-dd14f37195f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_0b4187c8-e987-4bf2-be83-c0bfdfdc1978" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_893ac02f-fb84-4149-b0ef-dd14f37195f5" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesEstimatedUsefulLivesDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SummaryofsignificantaccountingpoliciesEstimatedUsefulLivesDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesEstimatedUsefulLivesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_855934cc-ad53-4d31-8109-19b636909b9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2b74392d-2a7f-4233-a015-e2a3b04c6834" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_855934cc-ad53-4d31-8109-19b636909b9a" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2b74392d-2a7f-4233-a015-e2a3b04c6834" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2b74392d-2a7f-4233-a015-e2a3b04c6834" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_4cc0c553-5a27-4f02-b8ad-8ac7f1d8895e" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_f6e2b957-c5ba-4b03-8d1d-0682c67e8155" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:to="loc_us-gaap_BuildingMember_f6e2b957-c5ba-4b03-8d1d-0682c67e8155" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingImprovementsMember_89bc3fa6-01aa-4d61-a774-61d298a8e532" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:to="loc_us-gaap_BuildingImprovementsMember_89bc3fa6-01aa-4d61-a774-61d298a8e532" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_f8b19019-2867-4f7e-8552-5e1dbd63cbbf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_f8b19019-2867-4f7e-8552-5e1dbd63cbbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_caaab316-2459-4ab4-8fed-47e65e8b949f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_6ace4887-b4e9-453d-829b-5ed1faf056b0" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_caaab316-2459-4ab4-8fed-47e65e8b949f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_bc87778c-89c4-449c-9268-037a85f5036c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_2b74392d-2a7f-4233-a015-e2a3b04c6834" xlink:to="loc_srt_RangeAxis_bc87778c-89c4-449c-9268-037a85f5036c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_bc87778c-89c4-449c-9268-037a85f5036c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_bc87778c-89c4-449c-9268-037a85f5036c" xlink:to="loc_srt_RangeMember_bc87778c-89c4-449c-9268-037a85f5036c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d82f0a34-bb78-43c2-a888-089ae9b23bf8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_bc87778c-89c4-449c-9268-037a85f5036c" xlink:to="loc_srt_RangeMember_d82f0a34-bb78-43c2-a888-089ae9b23bf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_59f43e66-9380-43f6-b011-5462faeaeb0f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d82f0a34-bb78-43c2-a888-089ae9b23bf8" xlink:to="loc_srt_MinimumMember_59f43e66-9380-43f6-b011-5462faeaeb0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_1b9d22b5-fa5a-42a6-aeb2-13ae291db1f9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d82f0a34-bb78-43c2-a888-089ae9b23bf8" xlink:to="loc_srt_MaximumMember_1b9d22b5-fa5a-42a6-aeb2-13ae291db1f9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_b2210749-3956-4870-9512-e829f2dedc9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_855934cc-ad53-4d31-8109-19b636909b9a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_b2210749-3956-4870-9512-e829f2dedc9f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesAccountingforSharebasedCompensationDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SummaryofsignificantaccountingpoliciesAccountingforSharebasedCompensationDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesAccountingforSharebasedCompensationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_21faa3c9-588a-4f98-95a8-250ef8540b39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4689f263-7887-414b-870a-e840848c608d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_21faa3c9-588a-4f98-95a8-250ef8540b39" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4689f263-7887-414b-870a-e840848c608d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_acecb414-bf89-4818-96ef-ff9b50ea1c27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_4689f263-7887-414b-870a-e840848c608d" xlink:to="loc_us-gaap_PlanNameAxis_acecb414-bf89-4818-96ef-ff9b50ea1c27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_acecb414-bf89-4818-96ef-ff9b50ea1c27_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_acecb414-bf89-4818-96ef-ff9b50ea1c27" xlink:to="loc_us-gaap_PlanNameDomain_acecb414-bf89-4818-96ef-ff9b50ea1c27_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_58c30de1-0086-4d44-9500-1d9ff80ca5a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_acecb414-bf89-4818-96ef-ff9b50ea1c27" xlink:to="loc_us-gaap_PlanNameDomain_58c30de1-0086-4d44-9500-1d9ff80ca5a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_A2023EquityInducementPlanMember_88cc87da-33a6-48d7-aa33-92500dc27d3b" xlink:href="ebs-20231231.xsd#ebs_A2023EquityInducementPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_58c30de1-0086-4d44-9500-1d9ff80ca5a5" xlink:to="loc_ebs_A2023EquityInducementPlanMember_88cc87da-33a6-48d7-aa33-92500dc27d3b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_NumberOfShareBasedEmployeeCompensationPlans_f28c2a0b-6ac8-4166-b589-cb5f73c32220" xlink:href="ebs-20231231.xsd#ebs_NumberOfShareBasedEmployeeCompensationPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_21faa3c9-588a-4f98-95a8-250ef8540b39" xlink:to="loc_ebs_NumberOfShareBasedEmployeeCompensationPlans_f28c2a0b-6ac8-4166-b589-cb5f73c32220" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_875b0394-35ba-474c-a098-f8e1200f29ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_21faa3c9-588a-4f98-95a8-250ef8540b39" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_875b0394-35ba-474c-a098-f8e1200f29ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_520becc9-7655-45ad-8520-7d1bcb596d3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_21faa3c9-588a-4f98-95a8-250ef8540b39" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_520becc9-7655-45ad-8520-7d1bcb596d3c" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesDerivativeinstrumentsandhedgingactivitiesDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SummaryofsignificantaccountingpoliciesDerivativeinstrumentsandhedgingactivitiesDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SummaryofsignificantaccountingpoliciesDerivativeinstrumentsandhedgingactivitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_b5f804b4-35c7-46f0-9c9d-364d2c9c6e9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_e004defe-94bd-4791-9c50-e7b9f87637ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_b5f804b4-35c7-46f0-9c9d-364d2c9c6e9b" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_e004defe-94bd-4791-9c50-e7b9f87637ec" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_521dd64f-2550-4578-9788-72917d67fc90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_e004defe-94bd-4791-9c50-e7b9f87637ec" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_521dd64f-2550-4578-9788-72917d67fc90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_521dd64f-2550-4578-9788-72917d67fc90_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_521dd64f-2550-4578-9788-72917d67fc90" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_521dd64f-2550-4578-9788-72917d67fc90_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_081d4d6b-fc06-4efc-a3a4-686391ee9fc3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_521dd64f-2550-4578-9788-72917d67fc90" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_081d4d6b-fc06-4efc-a3a4-686391ee9fc3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_874ef520-d4d1-47d9-9a0a-b22a9ed6556d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_081d4d6b-fc06-4efc-a3a4-686391ee9fc3" xlink:to="loc_us-gaap_InterestRateSwapMember_874ef520-d4d1-47d9-9a0a-b22a9ed6556d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_e004defe-94bd-4791-9c50-e7b9f87637ec" xlink:to="loc_us-gaap_HedgingDesignationAxis_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f" xlink:to="loc_us-gaap_HedgingDesignationDomain_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_1078aea6-877e-4748-9e61-a4dcebc0fa97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_f4d8ce79-1ea2-46f7-8ab8-0a3c0a56a81f" xlink:to="loc_us-gaap_HedgingDesignationDomain_1078aea6-877e-4748-9e61-a4dcebc0fa97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_e8da609c-62f0-4dde-a656-39dc6cb02811" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_1078aea6-877e-4748-9e61-a4dcebc0fa97" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_e8da609c-62f0-4dde-a656-39dc6cb02811" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_0b0197c9-035b-4bd4-b69f-44750c17d803" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_b5f804b4-35c7-46f0-9c9d-364d2c9c6e9b" xlink:to="loc_us-gaap_DerivativeNotionalAmount_0b0197c9-035b-4bd4-b69f-44750c17d803" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DivestitureDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DivestitureDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DivestitureDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b7a04df0-b883-415a-b8ed-352dca868bd0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b7a04df0-b883-415a-b8ed-352dca868bd0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_74da88a3-867a-4d2e-ae10-f7d5f036b9d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b7a04df0-b883-415a-b8ed-352dca868bd0" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_74da88a3-867a-4d2e-ae10-f7d5f036b9d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_74da88a3-867a-4d2e-ae10-f7d5f036b9d4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_74da88a3-867a-4d2e-ae10-f7d5f036b9d4" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_74da88a3-867a-4d2e-ae10-f7d5f036b9d4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_a85423ed-46f1-42eb-b28b-b6c5d5ea58af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_74da88a3-867a-4d2e-ae10-f7d5f036b9d4" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_a85423ed-46f1-42eb-b28b-b6c5d5ea58af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f1636eba-c896-4fd9-9038-6592a678dfa9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_a85423ed-46f1-42eb-b28b-b6c5d5ea58af" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_f1636eba-c896-4fd9-9038-6592a678dfa9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_8297595e-18b0-4b1c-aa49-fd48f78a46ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b7a04df0-b883-415a-b8ed-352dca868bd0" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_8297595e-18b0-4b1c-aa49-fd48f78a46ee" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_8297595e-18b0-4b1c-aa49-fd48f78a46ee_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_8297595e-18b0-4b1c-aa49-fd48f78a46ee" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_8297595e-18b0-4b1c-aa49-fd48f78a46ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3c7ed2c1-db98-4230-83ff-0ee2b80698df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_8297595e-18b0-4b1c-aa49-fd48f78a46ee" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3c7ed2c1-db98-4230-83ff-0ee2b80698df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_TravelHealthBusinessMember_43310554-2308-414f-98d1-43545e9e38e4" xlink:href="ebs-20231231.xsd#ebs_TravelHealthBusinessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_3c7ed2c1-db98-4230-83ff-0ee2b80698df" xlink:to="loc_ebs_TravelHealthBusinessMember_43310554-2308-414f-98d1-43545e9e38e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationByTypeAxis_5a920333-633c-4e33-a1f0-6c9b67a5ad29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContingentConsiderationByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_b7a04df0-b883-415a-b8ed-352dca868bd0" xlink:to="loc_us-gaap_ContingentConsiderationByTypeAxis_5a920333-633c-4e33-a1f0-6c9b67a5ad29" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_5a920333-633c-4e33-a1f0-6c9b67a5ad29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_5a920333-633c-4e33-a1f0-6c9b67a5ad29" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_5a920333-633c-4e33-a1f0-6c9b67a5ad29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_6ddd5e45-70f1-43e8-afd7-a6a93b14ed4c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContingentConsiderationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_5a920333-633c-4e33-a1f0-6c9b67a5ad29" xlink:to="loc_us-gaap_ContingentConsiderationTypeDomain_6ddd5e45-70f1-43e8-afd7-a6a93b14ed4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DevelopmentBasedMilestonesMember_7f15a59b-00f9-435a-b428-7c188d350a51" xlink:href="ebs-20231231.xsd#ebs_DevelopmentBasedMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_6ddd5e45-70f1-43e8-afd7-a6a93b14ed4c" xlink:to="loc_ebs_DevelopmentBasedMilestonesMember_7f15a59b-00f9-435a-b428-7c188d350a51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SalesBasedMilestonesMember_15847d51-9b6a-41b5-8c22-28220fb204a6" xlink:href="ebs-20231231.xsd#ebs_SalesBasedMilestonesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_6ddd5e45-70f1-43e8-afd7-a6a93b14ed4c" xlink:to="loc_ebs_SalesBasedMilestonesMember_15847d51-9b6a-41b5-8c22-28220fb204a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_a98fedcf-b2e7-4bbe-80ad-90998d54bd29" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_a98fedcf-b2e7-4bbe-80ad-90998d54bd29" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DisposalGroupIncludingDiscontinuedOperationMaximumContingentConsiderationReceivable_84826903-75e3-45fa-a6f9-abc3ce54cf7d" xlink:href="ebs-20231231.xsd#ebs_DisposalGroupIncludingDiscontinuedOperationMaximumContingentConsiderationReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_ebs_DisposalGroupIncludingDiscontinuedOperationMaximumContingentConsiderationReceivable_84826903-75e3-45fa-a6f9-abc3ce54cf7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_9e8f3814-18aa-45bb-aabf-7fdd45ad0a47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_9e8f3814-18aa-45bb-aabf-7fdd45ad0a47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DispositionOfBusinessTransactionCosts_922555e5-aa54-43c6-8096-60960d424824" xlink:href="ebs-20231231.xsd#ebs_DispositionOfBusinessTransactionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_ebs_DispositionOfBusinessTransactionCosts_922555e5-aa54-43c6-8096-60960d424824" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonoperatingIncomeExpense_aed2cac4-60cc-4ae2-93c9-c9963a028eee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_8132f10f-e709-4206-a8ef-e113e4d9aaf0" xlink:to="loc_us-gaap_NonoperatingIncomeExpense_aed2cac4-60cc-4ae2-93c9-c9963a028eee" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#LonglivedassetimpairmentandrestructuringchargesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_a0f463f6-b00c-4a26-963b-775d735ec1d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_8ea77115-deda-4003-bc28-f79361f1b492" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_a0f463f6-b00c-4a26-963b-775d735ec1d1" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_8ea77115-deda-4003-bc28-f79361f1b492" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_aeda3f9b-9cff-4bf7-9ee3-6e757125e382" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_8ea77115-deda-4003-bc28-f79361f1b492" xlink:to="loc_us-gaap_RestructuringPlanAxis_aeda3f9b-9cff-4bf7-9ee3-6e757125e382" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_aeda3f9b-9cff-4bf7-9ee3-6e757125e382_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_aeda3f9b-9cff-4bf7-9ee3-6e757125e382" xlink:to="loc_us-gaap_RestructuringPlanDomain_aeda3f9b-9cff-4bf7-9ee3-6e757125e382_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_e4b7207f-bf1a-4bf8-bcbe-8b31351a4774" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_aeda3f9b-9cff-4bf7-9ee3-6e757125e382" xlink:to="loc_us-gaap_RestructuringPlanDomain_e4b7207f-bf1a-4bf8-bcbe-8b31351a4774" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanJanuary2023Member_238b72c7-81b5-426c-8668-1f4eea3d02d4" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanJanuary2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_e4b7207f-bf1a-4bf8-bcbe-8b31351a4774" xlink:to="loc_ebs_RestructuringPlanJanuary2023Member_238b72c7-81b5-426c-8668-1f4eea3d02d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanAugust2023Member_b2e9e848-c946-4768-a77f-084aed60e94b" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanAugust2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_e4b7207f-bf1a-4bf8-bcbe-8b31351a4774" xlink:to="loc_ebs_RestructuringPlanAugust2023Member_b2e9e848-c946-4768-a77f-084aed60e94b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_ec6a73c7-3306-4d0a-bd4e-597a680e5c43" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_a0f463f6-b00c-4a26-963b-775d735ec1d1" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_ec6a73c7-3306-4d0a-bd4e-597a680e5c43" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_b964e111-426d-4f7f-acbf-1dc567d3fb39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_a0f463f6-b00c-4a26-963b-775d735ec1d1" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_b964e111-426d-4f7f-acbf-1dc567d3fb39" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_32ba3272-a269-4a32-85e6-0a510f296782" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_a0f463f6-b00c-4a26-963b-775d735ec1d1" xlink:to="loc_us-gaap_RestructuringCharges_32ba3272-a269-4a32-85e6-0a510f296782" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleofImpairmentofLongLivedAssetsHeldandUsedbyAssetDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#LonglivedassetimpairmentandrestructuringchargesScheduleofImpairmentofLongLivedAssetsHeldandUsedbyAssetDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleofImpairmentofLongLivedAssetsHeldandUsedbyAssetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_65d6aee5-ea13-4740-8994-cb4ffc3d2251" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_a627aadc-fcd1-4732-bdda-3555851be278" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_65d6aee5-ea13-4740-8994-cb4ffc3d2251" xlink:to="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_a627aadc-fcd1-4732-bdda-3555851be278" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_c6c91c97-9963-4b78-ad80-4db7584b9ec1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfImpairedLongLivedAssetsHeldAndUsedTable_a627aadc-fcd1-4732-bdda-3555851be278" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_c6c91c97-9963-4b78-ad80-4db7584b9ec1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_c6c91c97-9963-4b78-ad80-4db7584b9ec1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_c6c91c97-9963-4b78-ad80-4db7584b9ec1" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_c6c91c97-9963-4b78-ad80-4db7584b9ec1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis_c6c91c97-9963-4b78-ad80-4db7584b9ec1" xlink:to="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_e9597c04-5906-48ef-b575-8015ba5ee0e3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_e9597c04-5906-48ef-b575-8015ba5ee0e3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_84e4adcf-8869-42f1-8867-8eabc205324e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_84e4adcf-8869-42f1-8867-8eabc205324e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_63144831-be7a-4084-b7d5-ec7d6d8056c2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_63144831-be7a-4084-b7d5-ec7d6d8056c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_f068b2ba-fd67-4b99-8846-462430e5b179" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetNameDomain_61531125-14fc-4dd7-92d5-3217379f76c2" xlink:to="loc_us-gaap_ConstructionInProgressMember_f068b2ba-fd67-4b99-8846-462430e5b179" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_3402cd5f-3b41-4875-a488-e2e330811421" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ImpairedLongLivedAssetsHeldAndUsedLineItems_65d6aee5-ea13-4740-8994-cb4ffc3d2251" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_3402cd5f-3b41-4875-a488-e2e330811421" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleRestructuringandRelatedCostsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#LonglivedassetimpairmentandrestructuringchargesScheduleRestructuringandRelatedCostsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleRestructuringandRelatedCostsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_ef62d67c-8ed4-4d56-8160-12bf1452e8b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_96535a9e-fe68-4931-aedf-7cb61e4ce0d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_ef62d67c-8ed4-4d56-8160-12bf1452e8b6" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_96535a9e-fe68-4931-aedf-7cb61e4ce0d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_4e63608c-3027-4c71-9735-682321fd0df2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_96535a9e-fe68-4931-aedf-7cb61e4ce0d2" xlink:to="loc_srt_ConsolidationItemsAxis_4e63608c-3027-4c71-9735-682321fd0df2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_4e63608c-3027-4c71-9735-682321fd0df2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_4e63608c-3027-4c71-9735-682321fd0df2" xlink:to="loc_srt_ConsolidationItemsDomain_4e63608c-3027-4c71-9735-682321fd0df2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_c590dc30-2f99-447c-88a6-3e12ed4e1021" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_4e63608c-3027-4c71-9735-682321fd0df2" xlink:to="loc_srt_ConsolidationItemsDomain_c590dc30-2f99-447c-88a6-3e12ed4e1021" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_322da45e-b771-471b-9157-c3c396ecad23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_c590dc30-2f99-447c-88a6-3e12ed4e1021" xlink:to="loc_us-gaap_OperatingSegmentsMember_322da45e-b771-471b-9157-c3c396ecad23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_fbb6b1f8-1056-4555-a5df-0f31fb66aa66" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_c590dc30-2f99-447c-88a6-3e12ed4e1021" xlink:to="loc_us-gaap_CorporateNonSegmentMember_fbb6b1f8-1056-4555-a5df-0f31fb66aa66" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_79884343-d9aa-4f9e-8da3-51730d580fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_96535a9e-fe68-4931-aedf-7cb61e4ce0d2" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_79884343-d9aa-4f9e-8da3-51730d580fb0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_79884343-d9aa-4f9e-8da3-51730d580fb0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_79884343-d9aa-4f9e-8da3-51730d580fb0" xlink:to="loc_us-gaap_SegmentDomain_79884343-d9aa-4f9e-8da3-51730d580fb0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_18d85546-02f2-4290-ac4a-a0a10f1cab58" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_79884343-d9aa-4f9e-8da3-51730d580fb0" xlink:to="loc_us-gaap_SegmentDomain_18d85546-02f2-4290-ac4a-a0a10f1cab58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductsSegmentMember_b016adba-3080-4a56-a54a-03f6f924c02b" xlink:href="ebs-20231231.xsd#ebs_CommercialProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_18d85546-02f2-4290-ac4a-a0a10f1cab58" xlink:to="loc_ebs_CommercialProductsSegmentMember_b016adba-3080-4a56-a54a-03f6f924c02b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MCMProductsSegmentMember_a33ee17a-c2d4-4485-aad7-869db044a737" xlink:href="ebs-20231231.xsd#ebs_MCMProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_18d85546-02f2-4290-ac4a-a0a10f1cab58" xlink:to="loc_ebs_MCMProductsSegmentMember_a33ee17a-c2d4-4485-aad7-869db044a737" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ServicesSegmentMember_a0cf73ed-0f7d-4e58-8e26-2d067c6a365c" xlink:href="ebs-20231231.xsd#ebs_ServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_18d85546-02f2-4290-ac4a-a0a10f1cab58" xlink:to="loc_ebs_ServicesSegmentMember_a0cf73ed-0f7d-4e58-8e26-2d067c6a365c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_96535a9e-fe68-4931-aedf-7cb61e4ce0d2" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_623f9e5e-b0b4-4ea8-a3f6-9eb5c363ce73" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnallocatedResearchAndDevelopmentMember_04154d79-42c2-4219-8ae9-cc7ff628b625" xlink:href="ebs-20231231.xsd#ebs_UnallocatedResearchAndDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:to="loc_ebs_UnallocatedResearchAndDevelopmentMember_04154d79-42c2-4219-8ae9-cc7ff628b625" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmployeeTransitionMember_0bc4d148-4043-4765-a911-6a24a6915f22" xlink:href="ebs-20231231.xsd#ebs_EmployeeTransitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:to="loc_ebs_EmployeeTransitionMember_0bc4d148-4043-4765-a911-6a24a6915f22" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_265549f8-f066-4b2c-abb9-e272fa20fe3d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:to="loc_us-gaap_EmployeeSeveranceMember_265549f8-f066-4b2c-abb9-e272fa20fe3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmployeeBenefitsMember_e480fd98-566f-4ae5-8819-55e88f1e9f96" xlink:href="ebs-20231231.xsd#ebs_EmployeeBenefitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_e8c72316-1a5a-4fc3-b6a1-574fd668aff9" xlink:to="loc_ebs_EmployeeBenefitsMember_e480fd98-566f-4ae5-8819-55e88f1e9f96" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_cf7878d0-ff57-494a-b4c3-ea7b32b80ab0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_ef62d67c-8ed4-4d56-8160-12bf1452e8b6" xlink:to="loc_us-gaap_RestructuringCharges_cf7878d0-ff57-494a-b4c3-ea7b32b80ab0" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleofRestructuringReservebyTypeofCostDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#LonglivedassetimpairmentandrestructuringchargesScheduleofRestructuringReservebyTypeofCostDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/LonglivedassetimpairmentandrestructuringchargesScheduleofRestructuringReservebyTypeofCostDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_8135e06b-227b-4d12-aad6-4a73dc32cc41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_72550e0e-9e10-4f6d-8d14-ee19cbb1492b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_8135e06b-227b-4d12-aad6-4a73dc32cc41" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_72550e0e-9e10-4f6d-8d14-ee19cbb1492b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_8a32cf3f-d071-49f8-ac78-a7426cb699bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_72550e0e-9e10-4f6d-8d14-ee19cbb1492b" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_8a32cf3f-d071-49f8-ac78-a7426cb699bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_8a32cf3f-d071-49f8-ac78-a7426cb699bc_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_8a32cf3f-d071-49f8-ac78-a7426cb699bc" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_8a32cf3f-d071-49f8-ac78-a7426cb699bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_32fd4d65-9fca-4abe-ae5a-6a1bf14e91af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_8a32cf3f-d071-49f8-ac78-a7426cb699bc" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_32fd4d65-9fca-4abe-ae5a-6a1bf14e91af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmployeeTransitionMember_73bec6d5-b294-4853-9f76-dec32c8e5642" xlink:href="ebs-20231231.xsd#ebs_EmployeeTransitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_32fd4d65-9fca-4abe-ae5a-6a1bf14e91af" xlink:to="loc_ebs_EmployeeTransitionMember_73bec6d5-b294-4853-9f76-dec32c8e5642" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_73fc66d6-cf65-4904-b460-e3296697c2df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_32fd4d65-9fca-4abe-ae5a-6a1bf14e91af" xlink:to="loc_us-gaap_EmployeeSeveranceMember_73fc66d6-cf65-4904-b460-e3296697c2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmployeeBenefitsMember_3c237bf3-d225-4b53-b8d9-57ff8b93f406" xlink:href="ebs-20231231.xsd#ebs_EmployeeBenefitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_32fd4d65-9fca-4abe-ae5a-6a1bf14e91af" xlink:to="loc_ebs_EmployeeBenefitsMember_3c237bf3-d225-4b53-b8d9-57ff8b93f406" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_a593d4f5-c999-4fee-be7b-e5c1d047189e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_72550e0e-9e10-4f6d-8d14-ee19cbb1492b" xlink:to="loc_us-gaap_RestructuringPlanAxis_a593d4f5-c999-4fee-be7b-e5c1d047189e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_a593d4f5-c999-4fee-be7b-e5c1d047189e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_a593d4f5-c999-4fee-be7b-e5c1d047189e" xlink:to="loc_us-gaap_RestructuringPlanDomain_a593d4f5-c999-4fee-be7b-e5c1d047189e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_0ae741b6-067b-499d-a016-7a789010e063" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_a593d4f5-c999-4fee-be7b-e5c1d047189e" xlink:to="loc_us-gaap_RestructuringPlanDomain_0ae741b6-067b-499d-a016-7a789010e063" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanJanuary2023Member_e55bcc9c-0434-4398-b518-0f168ace19f2" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanJanuary2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_0ae741b6-067b-499d-a016-7a789010e063" xlink:to="loc_ebs_RestructuringPlanJanuary2023Member_e55bcc9c-0434-4398-b518-0f168ace19f2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RestructuringPlanAugust2023Member_e95c4e73-8873-4aa5-bb6e-6d7026ed9d50" xlink:href="ebs-20231231.xsd#ebs_RestructuringPlanAugust2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_0ae741b6-067b-499d-a016-7a789010e063" xlink:to="loc_ebs_RestructuringPlanAugust2023Member_e95c4e73-8873-4aa5-bb6e-6d7026ed9d50" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_226eb136-d34f-4114-b38c-86f74e7608c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_8135e06b-227b-4d12-aad6-4a73dc32cc41" xlink:to="loc_us-gaap_RestructuringReserveRollForward_226eb136-d34f-4114-b38c-86f74e7608c4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_412e92f3-793b-4447-8cdb-b93e276c6bd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_226eb136-d34f-4114-b38c-86f74e7608c4" xlink:to="loc_us-gaap_RestructuringReserve_412e92f3-793b-4447-8cdb-b93e276c6bd9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_d9b48d92-487d-4dfd-8cce-f6f542868b02" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_226eb136-d34f-4114-b38c-86f74e7608c4" xlink:to="loc_us-gaap_RestructuringCharges_d9b48d92-487d-4dfd-8cce-f6f542868b02" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_96f96e25-e484-46c9-895d-f4c8f23c0749" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_226eb136-d34f-4114-b38c-86f74e7608c4" xlink:to="loc_us-gaap_PaymentsForRestructuring_96f96e25-e484-46c9-895d-f4c8f23c0749" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_89c5c538-7835-4372-a994-75e52fcdb4a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/PropertyplantandequipmentnetSummaryofPropertyPlantandEquipmentUsefulLivesDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#PropertyplantandequipmentnetSummaryofPropertyPlantandEquipmentUsefulLivesDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/PropertyplantandequipmentnetSummaryofPropertyPlantandEquipmentUsefulLivesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_602087ab-2bf2-48ec-abf3-059f0a761f50" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_364811bf-8ee8-4498-b8d0-358c0afe5a69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_602087ab-2bf2-48ec-abf3-059f0a761f50" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_364811bf-8ee8-4498-b8d0-358c0afe5a69" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_60211ff2-b200-42c9-9312-7ce1eb2b682a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_364811bf-8ee8-4498-b8d0-358c0afe5a69" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_60211ff2-b200-42c9-9312-7ce1eb2b682a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_60211ff2-b200-42c9-9312-7ce1eb2b682a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_60211ff2-b200-42c9-9312-7ce1eb2b682a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_60211ff2-b200-42c9-9312-7ce1eb2b682a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_60211ff2-b200-42c9-9312-7ce1eb2b682a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandAndLandImprovementsMember_5c5e0f4d-a50e-452a-b836-08021d6fb507" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LandAndLandImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:to="loc_us-gaap_LandAndLandImprovementsMember_5c5e0f4d-a50e-452a-b836-08021d6fb507" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingAndBuildingImprovementsMember_fafdf39c-1c76-4aa1-974e-2d2411d870b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BuildingAndBuildingImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:to="loc_us-gaap_BuildingAndBuildingImprovementsMember_fafdf39c-1c76-4aa1-974e-2d2411d870b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_88cac5e2-1d4a-4b46-826d-95244ed43337" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_88cac5e2-1d4a-4b46-826d-95244ed43337" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_34bc4c92-66f2-43dc-bbed-bc31e9047cfd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ComputerSoftwareIntangibleAssetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:to="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_34bc4c92-66f2-43dc-bbed-bc31e9047cfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_666f292b-3d1b-437e-ac67-4078cb014161" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_e1e42459-0fdb-469b-a7b1-664666cd78fc" xlink:to="loc_us-gaap_ConstructionInProgressMember_666f292b-3d1b-437e-ac67-4078cb014161" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_602087ab-2bf2-48ec-abf3-059f0a761f50" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_3c78de11-9d62-42b5-b235-ab9ff8e41bfb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_3c78de11-9d62-42b5-b235-ab9ff8e41bfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_a8d031f2-9d0a-4b9f-b502-d060df975e54" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_a8d031f2-9d0a-4b9f-b502-d060df975e54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_9b540080-19e4-4f60-8d07-8e271402b52a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_9b540080-19e4-4f60-8d07-8e271402b52a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_c42bcbef-a517-4243-9e68-baa1fc6713eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNetAbstract_74f94396-d416-4e29-8485-eab545eedd03" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_c42bcbef-a517-4243-9e68-baa1fc6713eb" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/PropertyplantandequipmentnetNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#PropertyplantandequipmentnetNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/PropertyplantandequipmentnetNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e169cd83-7b3f-430d-bfe1-df95e5b4f495" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_f2ab6995-b82e-459e-9c70-9b1c5b2c1d8c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e169cd83-7b3f-430d-bfe1-df95e5b4f495" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_f2ab6995-b82e-459e-9c70-9b1c5b2c1d8c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_54374bdf-c45f-437f-9483-b2952a98a4e9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_f2ab6995-b82e-459e-9c70-9b1c5b2c1d8c" xlink:to="loc_srt_MajorCustomersAxis_54374bdf-c45f-437f-9483-b2952a98a4e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_54374bdf-c45f-437f-9483-b2952a98a4e9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_54374bdf-c45f-437f-9483-b2952a98a4e9" xlink:to="loc_srt_NameOfMajorCustomerDomain_54374bdf-c45f-437f-9483-b2952a98a4e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_059726c0-6b12-412e-bbb5-ec6a69100c89" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_54374bdf-c45f-437f-9483-b2952a98a4e9" xlink:to="loc_srt_NameOfMajorCustomerDomain_059726c0-6b12-412e-bbb5-ec6a69100c89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_JansenPharmaceuticalsIncMember_92b69d33-f7d9-4713-9379-91c043dcac28" xlink:href="ebs-20231231.xsd#ebs_JansenPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_059726c0-6b12-412e-bbb5-ec6a69100c89" xlink:to="loc_ebs_JansenPharmaceuticalsIncMember_92b69d33-f7d9-4713-9379-91c043dcac28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_04c2f9d0-37a0-4ee6-b682-82926da98023" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_f2ab6995-b82e-459e-9c70-9b1c5b2c1d8c" xlink:to="loc_srt_ProductOrServiceAxis_04c2f9d0-37a0-4ee6-b682-82926da98023" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_04c2f9d0-37a0-4ee6-b682-82926da98023_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_04c2f9d0-37a0-4ee6-b682-82926da98023" xlink:to="loc_srt_ProductsAndServicesDomain_04c2f9d0-37a0-4ee6-b682-82926da98023_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6068758b-9a79-46c9-b47c-f935c7ad068c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_04c2f9d0-37a0-4ee6-b682-82926da98023" xlink:to="loc_srt_ProductsAndServicesDomain_6068758b-9a79-46c9-b47c-f935c7ad068c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_2ec0c343-5ed0-4c78-9104-547a7782a7cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6068758b-9a79-46c9-b47c-f935c7ad068c" xlink:to="loc_us-gaap_ServiceMember_2ec0c343-5ed0-4c78-9104-547a7782a7cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_cdb3644f-e244-410a-883a-8c6594d4a35f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e169cd83-7b3f-430d-bfe1-df95e5b4f495" xlink:to="loc_us-gaap_Depreciation_cdb3644f-e244-410a-883a-8c6594d4a35f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_90969b01-5b5a-4a66-b924-d492e43bc24c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_e169cd83-7b3f-430d-bfe1-df95e5b4f495" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_90969b01-5b5a-4a66-b924-d492e43bc24c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillScheduleofFinitelivedIntangibleAssetsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#IntangibleassetsandgoodwillScheduleofFinitelivedIntangibleAssetsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillScheduleofFinitelivedIntangibleAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_075a0163-b83a-45d3-a00f-32f176b47187" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_075a0163-b83a-45d3-a00f-32f176b47187" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_075a0163-b83a-45d3-a00f-32f176b47187_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_075a0163-b83a-45d3-a00f-32f176b47187" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_075a0163-b83a-45d3-a00f-32f176b47187_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_26343a8b-9dfd-492d-8166-e273a03d0d04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_075a0163-b83a-45d3-a00f-32f176b47187" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_26343a8b-9dfd-492d-8166-e273a03d0d04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_05cc6a47-eaa8-4b82-99e1-53009b19c9f4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_26343a8b-9dfd-492d-8166-e273a03d0d04" xlink:to="loc_us-gaap_ProductMember_05cc6a47-eaa8-4b82-99e1-53009b19c9f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_86798ca8-f3ce-43ee-9f67-e68f3c9b0f07" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_26343a8b-9dfd-492d-8166-e273a03d0d04" xlink:to="loc_us-gaap_CustomerRelationshipsMember_86798ca8-f3ce-43ee-9f67-e68f3c9b0f07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesMember_68e79568-11ab-4190-83f0-717c1819e212" xlink:href="ebs-20231231.xsd#ebs_BioservicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_26343a8b-9dfd-492d-8166-e273a03d0d04" xlink:to="loc_ebs_BioservicesMember_68e79568-11ab-4190-83f0-717c1819e212" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_98647c11-4811-44e8-88fd-423b9f3bf93d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_98647c11-4811-44e8-88fd-423b9f3bf93d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_98647c11-4811-44e8-88fd-423b9f3bf93d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_98647c11-4811-44e8-88fd-423b9f3bf93d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_98647c11-4811-44e8-88fd-423b9f3bf93d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_273af358-636a-4018-bb08-8008736bcb91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_98647c11-4811-44e8-88fd-423b9f3bf93d" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_273af358-636a-4018-bb08-8008736bcb91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_23cd94c9-8cb6-4fae-b3be-6d3fa9dc7e72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_273af358-636a-4018-bb08-8008736bcb91" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_23cd94c9-8cb6-4fae-b3be-6d3fa9dc7e72" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2287ad46-3fec-4b9f-a827-1322e5cdf699" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2287ad46-3fec-4b9f-a827-1322e5cdf699" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2287ad46-3fec-4b9f-a827-1322e5cdf699_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2287ad46-3fec-4b9f-a827-1322e5cdf699" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_2287ad46-3fec-4b9f-a827-1322e5cdf699_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6cc031d5-39db-4b9b-b63a-23cc9ca68ede" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_2287ad46-3fec-4b9f-a827-1322e5cdf699" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6cc031d5-39db-4b9b-b63a-23cc9ca68ede" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_TravelHealthBusinessMember_fe134382-12c6-409a-8e3b-3ce4bfb1b22e" xlink:href="ebs-20231231.xsd#ebs_TravelHealthBusinessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_6cc031d5-39db-4b9b-b63a-23cc9ca68ede" xlink:to="loc_ebs_TravelHealthBusinessMember_fe134382-12c6-409a-8e3b-3ce4bfb1b22e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionAxis_4fddc24b-a10a-4870-bfbd-cc67088ceb21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_us-gaap_AssetAcquisitionAxis_4fddc24b-a10a-4870-bfbd-cc67088ceb21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_4fddc24b-a10a-4870-bfbd-cc67088ceb21_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AssetAcquisitionAxis_4fddc24b-a10a-4870-bfbd-cc67088ceb21" xlink:to="loc_us-gaap_AssetAcquisitionDomain_4fddc24b-a10a-4870-bfbd-cc67088ceb21_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionDomain_78701e7a-7208-48f2-a5c2-409b750dbdc1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetAcquisitionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AssetAcquisitionAxis_4fddc24b-a10a-4870-bfbd-cc67088ceb21" xlink:to="loc_us-gaap_AssetAcquisitionDomain_78701e7a-7208-48f2-a5c2-409b750dbdc1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ChimerixMember_e91d033c-e0db-4cd7-ba1b-b43d1de9b56c" xlink:href="ebs-20231231.xsd#ebs_ChimerixMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetAcquisitionDomain_78701e7a-7208-48f2-a5c2-409b750dbdc1" xlink:to="loc_ebs_ChimerixMember_e91d033c-e0db-4cd7-ba1b-b43d1de9b56c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_1dfce939-eca3-4cab-8c5d-027bc88fd374" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_srt_MajorCustomersAxis_1dfce939-eca3-4cab-8c5d-027bc88fd374" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_1dfce939-eca3-4cab-8c5d-027bc88fd374_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_1dfce939-eca3-4cab-8c5d-027bc88fd374" xlink:to="loc_srt_NameOfMajorCustomerDomain_1dfce939-eca3-4cab-8c5d-027bc88fd374_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_67f8b406-a65d-47f6-be29-ade914d7b0b5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_1dfce939-eca3-4cab-8c5d-027bc88fd374" xlink:to="loc_srt_NameOfMajorCustomerDomain_67f8b406-a65d-47f6-be29-ade914d7b0b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BARDAMember_40f7df17-bb55-4729-af7d-9780c0d24a87" xlink:href="ebs-20231231.xsd#ebs_BARDAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_67f8b406-a65d-47f6-be29-ade914d7b0b5" xlink:to="loc_ebs_BARDAMember_40f7df17-bb55-4729-af7d-9780c0d24a87" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_9f71d3db-d4a7-4e3f-917d-d2055994bf57" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredFiniteLivedIntangibleAssetByMajorClassTable_d1293e84-1ba3-4a4a-baa1-ec66d7c2f65e" xlink:to="loc_srt_ProductOrServiceAxis_9f71d3db-d4a7-4e3f-917d-d2055994bf57" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9f71d3db-d4a7-4e3f-917d-d2055994bf57_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_9f71d3db-d4a7-4e3f-917d-d2055994bf57" xlink:to="loc_srt_ProductsAndServicesDomain_9f71d3db-d4a7-4e3f-917d-d2055994bf57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_3585ec65-2a82-4038-9220-193230abf433" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_9f71d3db-d4a7-4e3f-917d-d2055994bf57" xlink:to="loc_srt_ProductsAndServicesDomain_3585ec65-2a82-4038-9220-193230abf433" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EbangaMember_bdb38153-5b25-4028-a0a1-d3e20dbc4bd7" xlink:href="ebs-20231231.xsd#ebs_EbangaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_3585ec65-2a82-4038-9220-193230abf433" xlink:to="loc_ebs_EbangaMember_bdb38153-5b25-4028-a0a1-d3e20dbc4bd7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_ba8bc087-0ccf-4054-a581-9795bfdf9cf5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_ba8bc087-0ccf-4054-a581-9795bfdf9cf5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_6b5101c5-afaf-4548-a271-62f5e6076f4e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_6b5101c5-afaf-4548-a271-62f5e6076f4e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_674c923c-0376-48a9-b609-e557575a53de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_674c923c-0376-48a9-b609-e557575a53de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_bfd158a9-a54b-433b-961c-413c9c80fdcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_bfd158a9-a54b-433b-961c-413c9c80fdcc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent_a034e0f8-4d84-4c58-8677-223c0b62e8a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationIntangibleAssetsCurrent_a034e0f8-4d84-4c58-8677-223c0b62e8a5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_e4e894b3-c429-4d86-b3f6-3d2a4e0cb034" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_e4e894b3-c429-4d86-b3f6-3d2a4e0cb034" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_RevenueFromContractWithCustomerTermOfContract_644c3bdb-4deb-476a-b962-80f24d1ab835" xlink:href="ebs-20231231.xsd#ebs_RevenueFromContractWithCustomerTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems_a9cb8c4c-4a6c-4b58-af64-a3e121e5a144" xlink:to="loc_ebs_RevenueFromContractWithCustomerTermOfContract_644c3bdb-4deb-476a-b962-80f24d1ab835" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#IntangibleassetsandgoodwillNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_f777af68-5297-491c-b194-0bde6c180ada" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_c88a923d-f73a-445d-88c8-041a8f1fb939" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_f777af68-5297-491c-b194-0bde6c180ada" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_c88a923d-f73a-445d-88c8-041a8f1fb939" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitAxis_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReportingUnitAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_c88a923d-f73a-445d-88c8-041a8f1fb939" xlink:to="loc_us-gaap_ReportingUnitAxis_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ReportingUnitAxis_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716" xlink:to="loc_us-gaap_ReportingUnitDomain_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReportingUnitDomain_c4914b3b-cb30-4ff7-a25e-f277c38dc692" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReportingUnitDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ReportingUnitAxis_b9d9a8e5-e3d9-49b6-8a6f-9e857a1fb716" xlink:to="loc_us-gaap_ReportingUnitDomain_c4914b3b-cb30-4ff7-a25e-f277c38dc692" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MCMProductsMember_d66c70d0-2b79-4eb7-8e14-f0d253f32336" xlink:href="ebs-20231231.xsd#ebs_MCMProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReportingUnitDomain_c4914b3b-cb30-4ff7-a25e-f277c38dc692" xlink:to="loc_ebs_MCMProductsMember_d66c70d0-2b79-4eb7-8e14-f0d253f32336" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_4e353fd8-063f-4ef8-ba97-fda409eeb7b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_f777af68-5297-491c-b194-0bde6c180ada" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_4e353fd8-063f-4ef8-ba97-fda409eeb7b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_189859b7-21d6-4568-b576-023d35649550" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_f777af68-5297-491c-b194-0bde6c180ada" xlink:to="loc_us-gaap_Goodwill_189859b7-21d6-4568-b576-023d35649550" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillSummaryChangesinGoodwillDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#IntangibleassetsandgoodwillSummaryChangesinGoodwillDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/IntangibleassetsandgoodwillSummaryChangesinGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_2f02f7fd-7ff9-4ca5-83ce-f10aebe3fa28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_9903083b-357a-4c73-b050-e0410010e5f3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_2f02f7fd-7ff9-4ca5-83ce-f10aebe3fa28" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_9903083b-357a-4c73-b050-e0410010e5f3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_9903083b-357a-4c73-b050-e0410010e5f3" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a" xlink:to="loc_us-gaap_SegmentDomain_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_dff5b088-0768-4feb-9634-c7f23ca552d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8dd9bcdb-7f41-45c9-8630-8deb74b8e90a" xlink:to="loc_us-gaap_SegmentDomain_dff5b088-0768-4feb-9634-c7f23ca552d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductsSegmentMember_308abc7d-0a58-4937-b844-404ffe4e3032" xlink:href="ebs-20231231.xsd#ebs_CommercialProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_dff5b088-0768-4feb-9634-c7f23ca552d1" xlink:to="loc_ebs_CommercialProductsSegmentMember_308abc7d-0a58-4937-b844-404ffe4e3032" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MCMProductsSegmentMember_74be4052-3d90-41c1-967d-1231e696cdea" xlink:href="ebs-20231231.xsd#ebs_MCMProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_dff5b088-0768-4feb-9634-c7f23ca552d1" xlink:to="loc_ebs_MCMProductsSegmentMember_74be4052-3d90-41c1-967d-1231e696cdea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ServicesSegmentMember_3510baeb-5067-4636-9d6d-c856fda9a1e2" xlink:href="ebs-20231231.xsd#ebs_ServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_dff5b088-0768-4feb-9634-c7f23ca552d1" xlink:to="loc_ebs_ServicesSegmentMember_3510baeb-5067-4636-9d6d-c856fda9a1e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_935cae7d-1fd0-42c8-8ee5-c291a82c0584" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_2f02f7fd-7ff9-4ca5-83ce-f10aebe3fa28" xlink:to="loc_us-gaap_GoodwillRollForward_935cae7d-1fd0-42c8-8ee5-c291a82c0584" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_31d2dff8-efb0-476c-9e61-67c0afff7285" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_935cae7d-1fd0-42c8-8ee5-c291a82c0584" xlink:to="loc_us-gaap_Goodwill_31d2dff8-efb0-476c-9e61-67c0afff7285" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_635b5aec-f690-4d8e-81cf-c29cb0796a9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_935cae7d-1fd0-42c8-8ee5-c291a82c0584" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_635b5aec-f690-4d8e-81cf-c29cb0796a9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_9ea9c902-5fa5-4bd5-a536-dd3bf5c2b0c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_123edcdd-ca44-4cdf-8a90-863c3aad409d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_2f02f7fd-7ff9-4ca5-83ce-f10aebe3fa28" xlink:to="loc_us-gaap_GoodwillGross_123edcdd-ca44-4cdf-8a90-863c3aad409d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_5d5067dd-7b69-4d6c-9dd5-543db68ede89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_2f02f7fd-7ff9-4ca5-83ce-f10aebe3fa28" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_5d5067dd-7b69-4d6c-9dd5-543db68ede89" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/FairvaluemeasurementsFairValueMeasurementsRecurringandNonrecurringDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#FairvaluemeasurementsFairValueMeasurementsRecurringandNonrecurringDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/FairvaluemeasurementsFairValueMeasurementsRecurringandNonrecurringDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2206c1a1-05ab-4e92-8636-b9b67cae90e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2206c1a1-05ab-4e92-8636-b9b67cae90e4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_5e030335-1368-4300-9fe4-c8d33e974334" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2206c1a1-05ab-4e92-8636-b9b67cae90e4" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_5e030335-1368-4300-9fe4-c8d33e974334" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_5e030335-1368-4300-9fe4-c8d33e974334_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_5e030335-1368-4300-9fe4-c8d33e974334" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_5e030335-1368-4300-9fe4-c8d33e974334_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_72840d59-58c3-4b85-9f7d-b7f4620a4409" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_5e030335-1368-4300-9fe4-c8d33e974334" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_72840d59-58c3-4b85-9f7d-b7f4620a4409" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_012ba1a9-4268-4180-b311-32c7b37d2aa3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_72840d59-58c3-4b85-9f7d-b7f4620a4409" xlink:to="loc_us-gaap_MoneyMarketFundsMember_012ba1a9-4268-4180-b311-32c7b37d2aa3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BankTimeDepositsMember_e2ffdf55-3994-4011-a43f-df50bfe4e59e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BankTimeDepositsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_72840d59-58c3-4b85-9f7d-b7f4620a4409" xlink:to="loc_us-gaap_BankTimeDepositsMember_e2ffdf55-3994-4011-a43f-df50bfe4e59e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e94bba42-6282-4474-b716-0996b6aa9176" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_2206c1a1-05ab-4e92-8636-b9b67cae90e4" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e94bba42-6282-4474-b716-0996b6aa9176" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e94bba42-6282-4474-b716-0996b6aa9176_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e94bba42-6282-4474-b716-0996b6aa9176" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e94bba42-6282-4474-b716-0996b6aa9176_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1a12ca9d-7784-42aa-8cfd-594c115e30ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_e94bba42-6282-4474-b716-0996b6aa9176" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1a12ca9d-7784-42aa-8cfd-594c115e30ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_256ee121-2006-4c43-96b8-8a99019ac8f5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1a12ca9d-7784-42aa-8cfd-594c115e30ca" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_256ee121-2006-4c43-96b8-8a99019ac8f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_b194d6ac-a5e1-4a95-bdca-d5a4dbef4f91" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1a12ca9d-7784-42aa-8cfd-594c115e30ca" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_b194d6ac-a5e1-4a95-bdca-d5a4dbef4f91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_da65ba30-5c59-491f-a6d5-c7cab2436fff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_1a12ca9d-7784-42aa-8cfd-594c115e30ca" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_da65ba30-5c59-491f-a6d5-c7cab2436fff" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_a70d0e4f-0438-48f9-9b00-6b63478e5f39" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_a70d0e4f-0438-48f9-9b00-6b63478e5f39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_976a3d0d-fa3a-404b-91ed-d98c87b9542e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_DerivativeAssets_976a3d0d-fa3a-404b-91ed-d98c87b9542e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_50b8a1a8-2493-465e-a6d3-9a93a9e99b71" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_50b8a1a8-2493-465e-a6d3-9a93a9e99b71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_47576cbf-82cf-43d2-828e-788e83f7ee7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_47576cbf-82cf-43d2-828e-788e83f7ee7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_3944eb1a-8fc7-4c42-99b3-3d3ced74c039" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_3944eb1a-8fc7-4c42-99b3-3d3ced74c039" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration_21452e9d-ce8d-43e1-81b6-6b894e2f592a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_7f584104-77b6-4d65-8364-2a27c2d44220" xlink:to="loc_us-gaap_DerivativeAssetStatementOfFinancialPositionExtensibleEnumeration_21452e9d-ce8d-43e1-81b6-6b894e2f592a" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/FairvaluemeasurementsNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#FairvaluemeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/FairvaluemeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d00f13ce-bf49-41b4-81d4-989bd8ccaa74" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d00f13ce-bf49-41b4-81d4-989bd8ccaa74" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_9b9e54c3-8d2d-4a57-9bf6-37515db5de65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d00f13ce-bf49-41b4-81d4-989bd8ccaa74" xlink:to="loc_us-gaap_DebtInstrumentAxis_9b9e54c3-8d2d-4a57-9bf6-37515db5de65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9b9e54c3-8d2d-4a57-9bf6-37515db5de65_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_9b9e54c3-8d2d-4a57-9bf6-37515db5de65" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9b9e54c3-8d2d-4a57-9bf6-37515db5de65_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_30a9f8ee-276b-4450-9886-b8bfa249834e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_9b9e54c3-8d2d-4a57-9bf6-37515db5de65" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_30a9f8ee-276b-4450-9886-b8bfa249834e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_8cf10033-9657-4dae-8207-9ece4e1dfb75" xlink:href="ebs-20231231.xsd#ebs_SeniorUnsecuredNotesDueAugust2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_30a9f8ee-276b-4450-9886-b8bfa249834e" xlink:to="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_8cf10033-9657-4dae-8207-9ece4e1dfb75" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1e142e06-bab4-4597-bf3f-08ccd7c7eac6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_d00f13ce-bf49-41b4-81d4-989bd8ccaa74" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1e142e06-bab4-4597-bf3f-08ccd7c7eac6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1e142e06-bab4-4597-bf3f-08ccd7c7eac6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1e142e06-bab4-4597-bf3f-08ccd7c7eac6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1e142e06-bab4-4597-bf3f-08ccd7c7eac6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bb4bdf86-039b-45b4-9f41-74b2120d9dc8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1e142e06-bab4-4597-bf3f-08ccd7c7eac6" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bb4bdf86-039b-45b4-9f41-74b2120d9dc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_cc180ae1-35b3-43f4-9fdd-18b6c159914a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bb4bdf86-039b-45b4-9f41-74b2120d9dc8" xlink:to="loc_us-gaap_SeniorNotesMember_cc180ae1-35b3-43f4-9fdd-18b6c159914a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList_dcf201c2-0789-4154-9bc5-1ae23d2d7bbe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:to="loc_us-gaap_FairValueRecurringBasisUnobservableInputReconciliationLiabilityGainLossStatementOfIncomeExtensibleList_dcf201c2-0789-4154-9bc5-1ae23d2d7bbe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_7076c55f-a855-4f5a-a4d6-c40b689a7ec6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityCurrent_7076c55f-a855-4f5a-a4d6-c40b689a7ec6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0c26d67e-6a6b-46ec-9992-2ac63a5768a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_0c26d67e-6a6b-46ec-9992-2ac63a5768a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_a8bee089-2fff-4856-a059-34230fbd3fdb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_eb68d377-e8fc-4aef-8069-3dd79a89e37f" xlink:to="loc_us-gaap_LongTermDebtFairValue_a8bee089-2fff-4856-a059-34230fbd3fdb" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/FairvaluemeasurementsLevel3SignificantUnobservableInputsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#FairvaluemeasurementsLevel3SignificantUnobservableInputsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/FairvaluemeasurementsLevel3SignificantUnobservableInputsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_e095a631-b6a9-48b9-bd31-a73d80c89863" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_e095a631-b6a9-48b9-bd31-a73d80c89863" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ea28d292-89fa-4350-a2e0-901976e0dadd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ea28d292-89fa-4350-a2e0-901976e0dadd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ea28d292-89fa-4350-a2e0-901976e0dadd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ea28d292-89fa-4350-a2e0-901976e0dadd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ea28d292-89fa-4350-a2e0-901976e0dadd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_93f97602-d252-4c4e-bfab-0da85b077cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_ea28d292-89fa-4350-a2e0-901976e0dadd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_93f97602-d252-4c4e-bfab-0da85b077cf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_2ea44385-29b6-4a5f-9147-f8e2033a4386" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_93f97602-d252-4c4e-bfab-0da85b077cf6" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_2ea44385-29b6-4a5f-9147-f8e2033a4386" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_de89aa60-91df-46b2-93e2-dc6feedb8c89" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_de89aa60-91df-46b2-93e2-dc6feedb8c89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_de89aa60-91df-46b2-93e2-dc6feedb8c89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_de89aa60-91df-46b2-93e2-dc6feedb8c89" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_de89aa60-91df-46b2-93e2-dc6feedb8c89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_9a066af7-2bea-4fd2-8dae-c6b7afe1c1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_de89aa60-91df-46b2-93e2-dc6feedb8c89" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_9a066af7-2bea-4fd2-8dae-c6b7afe1c1ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_d3b83cd4-c9f0-4492-83ee-644f357240c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_9a066af7-2bea-4fd2-8dae-c6b7afe1c1ba" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_d3b83cd4-c9f0-4492-83ee-644f357240c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeAxis_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:to="loc_us-gaap_MeasurementInputTypeAxis_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputTypeDomain_0bb1b8f5-18a2-4695-b947-59bb38a21bf6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_MeasurementInputTypeAxis_397e1368-8d5e-4a5d-9e2e-05ca4415ba5c" xlink:to="loc_us-gaap_MeasurementInputTypeDomain_0bb1b8f5-18a2-4695-b947-59bb38a21bf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MeasurementInputDiscountRateMember_f86f6aa1-3ca5-46fc-be22-b7fdc6e586dd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MeasurementInputDiscountRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_0bb1b8f5-18a2-4695-b947-59bb38a21bf6" xlink:to="loc_us-gaap_MeasurementInputDiscountRateMember_f86f6aa1-3ca5-46fc-be22-b7fdc6e586dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MeasurementInputProbabilityOfPaymentMember_7cfa67c4-1719-460a-8a9d-f1c289667264" xlink:href="ebs-20231231.xsd#ebs_MeasurementInputProbabilityOfPaymentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MeasurementInputTypeDomain_0bb1b8f5-18a2-4695-b947-59bb38a21bf6" xlink:to="loc_ebs_MeasurementInputProbabilityOfPaymentMember_7cfa67c4-1719-460a-8a9d-f1c289667264" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueAxis_7d2feb9d-3023-430e-8b94-4d2e3764d50e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:to="loc_us-gaap_ValuationTechniqueAxis_7d2feb9d-3023-430e-8b94-4d2e3764d50e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_7d2feb9d-3023-430e-8b94-4d2e3764d50e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationTechniqueAxis_7d2feb9d-3023-430e-8b94-4d2e3764d50e" xlink:to="loc_us-gaap_ValuationTechniqueDomain_7d2feb9d-3023-430e-8b94-4d2e3764d50e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDomain_9f8e9812-9659-42df-9cb5-514bf7bbf340" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationTechniqueAxis_7d2feb9d-3023-430e-8b94-4d2e3764d50e" xlink:to="loc_us-gaap_ValuationTechniqueDomain_9f8e9812-9659-42df-9cb5-514bf7bbf340" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_6897b712-5564-40e8-a3ed-5e3a29106818" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationTechniqueDiscountedCashFlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationTechniqueDomain_9f8e9812-9659-42df-9cb5-514bf7bbf340" xlink:to="loc_us-gaap_ValuationTechniqueDiscountedCashFlowMember_6897b712-5564-40e8-a3ed-5e3a29106818" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ddda1d5f-3985-4690-8fbc-2a15b83d70a3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesTable_d1eb0643-6ca3-4e29-95ba-5db7822f7c05" xlink:to="loc_srt_RangeAxis_ddda1d5f-3985-4690-8fbc-2a15b83d70a3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ddda1d5f-3985-4690-8fbc-2a15b83d70a3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ddda1d5f-3985-4690-8fbc-2a15b83d70a3" xlink:to="loc_srt_RangeMember_ddda1d5f-3985-4690-8fbc-2a15b83d70a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d42fa58d-a9f5-43b8-badd-442dd26f6fb4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ddda1d5f-3985-4690-8fbc-2a15b83d70a3" xlink:to="loc_srt_RangeMember_d42fa58d-a9f5-43b8-badd-442dd26f6fb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_1df9b11e-4e1a-4a3e-8fe0-2466574fa539" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d42fa58d-a9f5-43b8-badd-442dd26f6fb4" xlink:to="loc_srt_MinimumMember_1df9b11e-4e1a-4a3e-8fe0-2466574fa539" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_0159908a-f7b5-4b41-95ad-a92216029182" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d42fa58d-a9f5-43b8-badd-442dd26f6fb4" xlink:to="loc_srt_MaximumMember_0159908a-f7b5-4b41-95ad-a92216029182" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_53a6c167-75ca-49fe-b04c-fbbc7bc663a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_e095a631-b6a9-48b9-bd31-a73d80c89863" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_53a6c167-75ca-49fe-b04c-fbbc7bc663a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput_89e51145-8e21-421d-a934-e1f757035bb2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems_e095a631-b6a9-48b9-bd31-a73d80c89863" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiabilityMeasurementInput_89e51145-8e21-421d-a934-e1f757035bb2" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DerivativeInstrumentsandhedgingactivitiesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_f86aba09-9516-4f83-ae22-d4869f480e47" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_69e3580e-c28c-467e-9f1d-1de17d960db2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_f86aba09-9516-4f83-ae22-d4869f480e47" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_69e3580e-c28c-467e-9f1d-1de17d960db2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_d97a352c-ff1f-4140-aa90-87d707c0b73e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_69e3580e-c28c-467e-9f1d-1de17d960db2" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_d97a352c-ff1f-4140-aa90-87d707c0b73e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d97a352c-ff1f-4140-aa90-87d707c0b73e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d97a352c-ff1f-4140-aa90-87d707c0b73e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d97a352c-ff1f-4140-aa90-87d707c0b73e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_765bb979-9910-4f6e-abfe-e4303f2d5469" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d97a352c-ff1f-4140-aa90-87d707c0b73e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_765bb979-9910-4f6e-abfe-e4303f2d5469" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_f9a1ef3d-76f1-41a0-baa0-ac97e234613b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_765bb979-9910-4f6e-abfe-e4303f2d5469" xlink:to="loc_us-gaap_InterestRateSwapMember_f9a1ef3d-76f1-41a0-baa0-ac97e234613b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_e76a2901-64a7-49c2-b794-fd5a9861735e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_69e3580e-c28c-467e-9f1d-1de17d960db2" xlink:to="loc_us-gaap_HedgingDesignationAxis_e76a2901-64a7-49c2-b794-fd5a9861735e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_e76a2901-64a7-49c2-b794-fd5a9861735e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_e76a2901-64a7-49c2-b794-fd5a9861735e" xlink:to="loc_us-gaap_HedgingDesignationDomain_e76a2901-64a7-49c2-b794-fd5a9861735e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_ca965ef2-0271-4238-998b-641b8d55e916" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_e76a2901-64a7-49c2-b794-fd5a9861735e" xlink:to="loc_us-gaap_HedgingDesignationDomain_ca965ef2-0271-4238-998b-641b8d55e916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_419a066c-4642-4dd0-aff8-5a6042465fdb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_ca965ef2-0271-4238-998b-641b8d55e916" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_419a066c-4642-4dd0-aff8-5a6042465fdb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_191ee2a0-a9e1-44d7-96e9-15e4ff9ce832" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_f86aba09-9516-4f83-ae22-d4869f480e47" xlink:to="loc_us-gaap_DerivativeNotionalAmount_191ee2a0-a9e1-44d7-96e9-15e4ff9ce832" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesFairValuebyBalanceSheetLocationDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DerivativeInstrumentsandhedgingactivitiesFairValuebyBalanceSheetLocationDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesFairValuebyBalanceSheetLocationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativesFairValueLineItems_54acea42-08a4-4c4c-a184-e40be5c0d886" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativesFairValueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c286984e-ad2d-4131-a3b0-aa356570154e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_54acea42-08a4-4c4c-a184-e40be5c0d886" xlink:to="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c286984e-ad2d-4131-a3b0-aa356570154e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_8fdf6d80-ed09-4c02-a2d8-931cae60bbab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c286984e-ad2d-4131-a3b0-aa356570154e" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_8fdf6d80-ed09-4c02-a2d8-931cae60bbab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8fdf6d80-ed09-4c02-a2d8-931cae60bbab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8fdf6d80-ed09-4c02-a2d8-931cae60bbab" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8fdf6d80-ed09-4c02-a2d8-931cae60bbab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_1ccdf3ea-028b-4ad0-b189-3ceaedaaccda" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_8fdf6d80-ed09-4c02-a2d8-931cae60bbab" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_1ccdf3ea-028b-4ad0-b189-3ceaedaaccda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_8fa82382-9ff4-42ac-ba1b-cfe609d7c8bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_1ccdf3ea-028b-4ad0-b189-3ceaedaaccda" xlink:to="loc_us-gaap_InterestRateSwapMember_8fa82382-9ff4-42ac-ba1b-cfe609d7c8bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_707ab5a2-b35a-4172-8b79-487d666be4e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c286984e-ad2d-4131-a3b0-aa356570154e" xlink:to="loc_us-gaap_HedgingDesignationAxis_707ab5a2-b35a-4172-8b79-487d666be4e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_707ab5a2-b35a-4172-8b79-487d666be4e8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_707ab5a2-b35a-4172-8b79-487d666be4e8" xlink:to="loc_us-gaap_HedgingDesignationDomain_707ab5a2-b35a-4172-8b79-487d666be4e8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_01614d32-51da-4602-b3a7-36cfc8c1689b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_707ab5a2-b35a-4172-8b79-487d666be4e8" xlink:to="loc_us-gaap_HedgingDesignationDomain_01614d32-51da-4602-b3a7-36cfc8c1689b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_69975ddc-2135-4f21-9be6-ad15a3fec407" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_01614d32-51da-4602-b3a7-36cfc8c1689b" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_69975ddc-2135-4f21-9be6-ad15a3fec407" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_301efa23-d9a0-444b-9b44-4d53a74c3987" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValuesDerivativesBalanceSheetLocationByDerivativeContractTypeByHedgingDesignationTable_c286984e-ad2d-4131-a3b0-aa356570154e" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_301efa23-d9a0-444b-9b44-4d53a74c3987" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_301efa23-d9a0-444b-9b44-4d53a74c3987_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_301efa23-d9a0-444b-9b44-4d53a74c3987" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_301efa23-d9a0-444b-9b44-4d53a74c3987_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_a877c4ce-28ac-426c-b42d-b8e591f76d20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_301efa23-d9a0-444b-9b44-4d53a74c3987" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_a877c4ce-28ac-426c-b42d-b8e591f76d20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_24e2cf97-8b74-46ab-822a-09ebd8ea2ee9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_a877c4ce-28ac-426c-b42d-b8e591f76d20" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_24e2cf97-8b74-46ab-822a-09ebd8ea2ee9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_ff6712ae-5857-4c5f-98bc-7b62b2995833" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativesFairValueLineItems_54acea42-08a4-4c4c-a184-e40be5c0d886" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_ff6712ae-5857-4c5f-98bc-7b62b2995833" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesCashFlowHedgingonAOCIDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DerivativeInstrumentsandhedgingactivitiesCashFlowHedgingonAOCIDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DerivativeInstrumentsandhedgingactivitiesCashFlowHedgingonAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_05e20f4d-abb9-4858-ba96-3126f04e790b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_f6ac687b-3dfc-4d9f-a6f4-81eaf9c69e44" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_05e20f4d-abb9-4858-ba96-3126f04e790b" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_f6ac687b-3dfc-4d9f-a6f4-81eaf9c69e44" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_251f6fd4-8143-4df3-a4aa-d5129fc07024" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_f6ac687b-3dfc-4d9f-a6f4-81eaf9c69e44" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_251f6fd4-8143-4df3-a4aa-d5129fc07024" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_251f6fd4-8143-4df3-a4aa-d5129fc07024_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_251f6fd4-8143-4df3-a4aa-d5129fc07024" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_251f6fd4-8143-4df3-a4aa-d5129fc07024_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_d5ae1b27-1e32-4dcb-a151-12f39f7bf216" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_251f6fd4-8143-4df3-a4aa-d5129fc07024" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_d5ae1b27-1e32-4dcb-a151-12f39f7bf216" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseMember_22da4b03-1b3f-43f9-b2dc-1390fdfc7303" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_d5ae1b27-1e32-4dcb-a151-12f39f7bf216" xlink:to="loc_us-gaap_InterestExpenseMember_22da4b03-1b3f-43f9-b2dc-1390fdfc7303" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_202894ee-51eb-40af-832a-7d2f898ad1bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_f6ac687b-3dfc-4d9f-a6f4-81eaf9c69e44" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_202894ee-51eb-40af-832a-7d2f898ad1bd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_202894ee-51eb-40af-832a-7d2f898ad1bd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_202894ee-51eb-40af-832a-7d2f898ad1bd" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_202894ee-51eb-40af-832a-7d2f898ad1bd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_99593606-e1fb-4355-9c26-0e7878e4eab1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_202894ee-51eb-40af-832a-7d2f898ad1bd" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_99593606-e1fb-4355-9c26-0e7878e4eab1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_ee17628b-a043-4b77-add7-4916cd4e82e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_99593606-e1fb-4355-9c26-0e7878e4eab1" xlink:to="loc_us-gaap_InterestRateSwapMember_ee17628b-a043-4b77-add7-4916cd4e82e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_f1f812c7-e089-422d-87ff-b50a3f31466a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresTable_f6ac687b-3dfc-4d9f-a6f4-81eaf9c69e44" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_f1f812c7-e089-422d-87ff-b50a3f31466a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_f1f812c7-e089-422d-87ff-b50a3f31466a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_f1f812c7-e089-422d-87ff-b50a3f31466a" xlink:to="loc_us-gaap_HedgingRelationshipDomain_f1f812c7-e089-422d-87ff-b50a3f31466a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_1a52a96b-c9d6-494f-9133-d1b718551f08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_f1f812c7-e089-422d-87ff-b50a3f31466a" xlink:to="loc_us-gaap_HedgingRelationshipDomain_1a52a96b-c9d6-494f-9133-d1b718551f08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgingMember_2821b3d3-217f-484a-96e1-6d344e636bcc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashFlowHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_1a52a96b-c9d6-494f-9133-d1b718551f08" xlink:to="loc_us-gaap_CashFlowHedgingMember_2821b3d3-217f-484a-96e1-6d344e636bcc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_7f037e76-0e2b-4c6c-972f-20413db5a0f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosuresLineItems_05e20f4d-abb9-4858-ba96-3126f04e790b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_7f037e76-0e2b-4c6c-972f-20413db5a0f8" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DebtComponentsofLongtermIndebtednessDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DebtComponentsofLongtermIndebtednessDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DebtComponentsofLongtermIndebtednessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_99776ad0-e8a6-408c-b17e-7d81e5d248c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_DebtInstrumentTable_99776ad0-e8a6-408c-b17e-7d81e5d248c5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_9666ebe1-0ad9-4150-8da4-2af3293aeff1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_99776ad0-e8a6-408c-b17e-7d81e5d248c5" xlink:to="loc_us-gaap_DebtInstrumentAxis_9666ebe1-0ad9-4150-8da4-2af3293aeff1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9666ebe1-0ad9-4150-8da4-2af3293aeff1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_9666ebe1-0ad9-4150-8da4-2af3293aeff1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9666ebe1-0ad9-4150-8da4-2af3293aeff1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4078245b-7722-4d74-a2cd-33137ff654b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_9666ebe1-0ad9-4150-8da4-2af3293aeff1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4078245b-7722-4d74-a2cd-33137ff654b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_f3d809e0-def6-496b-b30b-5213aae3f78a" xlink:href="ebs-20231231.xsd#ebs_SeniorUnsecuredNotesDueAugust2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4078245b-7722-4d74-a2cd-33137ff654b0" xlink:to="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_f3d809e0-def6-496b-b30b-5213aae3f78a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OtherLongTermDebtFacilityMember_a4b80680-5dce-49d9-a2f2-bda3930548f3" xlink:href="ebs-20231231.xsd#ebs_OtherLongTermDebtFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4078245b-7722-4d74-a2cd-33137ff654b0" xlink:to="loc_ebs_OtherLongTermDebtFacilityMember_a4b80680-5dce-49d9-a2f2-bda3930548f3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_077ce729-e488-4d9f-a6f2-28d6c1207488" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_99776ad0-e8a6-408c-b17e-7d81e5d248c5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_077ce729-e488-4d9f-a6f2-28d6c1207488" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_077ce729-e488-4d9f-a6f2-28d6c1207488_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_077ce729-e488-4d9f-a6f2-28d6c1207488" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_077ce729-e488-4d9f-a6f2-28d6c1207488_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_bccb0096-52aa-443b-a09b-a7be034c7367" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_077ce729-e488-4d9f-a6f2-28d6c1207488" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_bccb0096-52aa-443b-a09b-a7be034c7367" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_1481ab99-3a88-4f0d-bb81-992bae21b50b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bccb0096-52aa-443b-a09b-a7be034c7367" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_1481ab99-3a88-4f0d-bb81-992bae21b50b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_516ae889-4a25-4605-8f4d-02ef0abb5ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bccb0096-52aa-443b-a09b-a7be034c7367" xlink:to="loc_us-gaap_LineOfCreditMember_516ae889-4a25-4605-8f4d-02ef0abb5ad2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_2d2a0bd2-e1a1-4bb2-8759-84430acd57fc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_bccb0096-52aa-443b-a09b-a7be034c7367" xlink:to="loc_us-gaap_SeniorNotesMember_2d2a0bd2-e1a1-4bb2-8759-84430acd57fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_74d6fa1e-1a0c-4a1c-b541-9e1871083353" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_99776ad0-e8a6-408c-b17e-7d81e5d248c5" xlink:to="loc_us-gaap_CreditFacilityAxis_74d6fa1e-1a0c-4a1c-b541-9e1871083353" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_74d6fa1e-1a0c-4a1c-b541-9e1871083353_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_74d6fa1e-1a0c-4a1c-b541-9e1871083353" xlink:to="loc_us-gaap_CreditFacilityDomain_74d6fa1e-1a0c-4a1c-b541-9e1871083353_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_db0248b7-6bd3-4625-b64f-956fe629c224" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_74d6fa1e-1a0c-4a1c-b541-9e1871083353" xlink:to="loc_us-gaap_CreditFacilityDomain_db0248b7-6bd3-4625-b64f-956fe629c224" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_38b3d40d-5db3-44c1-9755-8d151ba9d9b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_db0248b7-6bd3-4625-b64f-956fe629c224" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_38b3d40d-5db3-44c1-9755-8d151ba9d9b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_9b47a28e-33ce-41e0-839a-d0a0c220f4fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_9b47a28e-33ce-41e0-839a-d0a0c220f4fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_a5655b63-2894-4119-9e97-2dd4447aaefd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_LongTermDebt_a5655b63-2894-4119-9e97-2dd4447aaefd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_d1da990d-1989-4233-8812-01645d87980c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_LongTermDebtCurrent_d1da990d-1989-4233-8812-01645d87980c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_e3e5a0ec-f834-4491-aa54-f60bf5aa15de" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFinanceCostsNoncurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_DeferredFinanceCostsNoncurrentNet_e3e5a0ec-f834-4491-aa54-f60bf5aa15de" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_1d1e5163-2f0b-4117-b2ce-3bc192b4d388" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a742ca0e-ed50-4c2d-85e0-8dea9a35d376" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_1d1e5163-2f0b-4117-b2ce-3bc192b4d388" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/DebtNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#DebtNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/DebtNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_1aa01c45-a433-45df-8ba8-0b40d40e42b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_1aa01c45-a433-45df-8ba8-0b40d40e42b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_1aa01c45-a433-45df-8ba8-0b40d40e42b1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1aa01c45-a433-45df-8ba8-0b40d40e42b1" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_1aa01c45-a433-45df-8ba8-0b40d40e42b1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_c831a4be-fcd8-439a-bff3-f37790a19abe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_1aa01c45-a433-45df-8ba8-0b40d40e42b1" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_c831a4be-fcd8-439a-bff3-f37790a19abe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_9f8f5fdb-59d3-49d6-96f1-e27ee422c13c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_c831a4be-fcd8-439a-bff3-f37790a19abe" xlink:to="loc_us-gaap_LineOfCreditMember_9f8f5fdb-59d3-49d6-96f1-e27ee422c13c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_de3dfc4c-768e-4e78-80f8-9b95834b9b5c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_c831a4be-fcd8-439a-bff3-f37790a19abe" xlink:to="loc_us-gaap_SeniorNotesMember_de3dfc4c-768e-4e78-80f8-9b95834b9b5c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableOtherPayablesMember_011a6940-d560-4963-beb9-df2f39b82518" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NotesPayableOtherPayablesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_c831a4be-fcd8-439a-bff3-f37790a19abe" xlink:to="loc_us-gaap_NotesPayableOtherPayablesMember_011a6940-d560-4963-beb9-df2f39b82518" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_7718328e-64f5-4abc-9e10-3b446b32bdf1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_DebtInstrumentAxis_7718328e-64f5-4abc-9e10-3b446b32bdf1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_7718328e-64f5-4abc-9e10-3b446b32bdf1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_7718328e-64f5-4abc-9e10-3b446b32bdf1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_7718328e-64f5-4abc-9e10-3b446b32bdf1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_f3190abf-b926-4f92-a809-96b27f005da2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_7718328e-64f5-4abc-9e10-3b446b32bdf1" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_f3190abf-b926-4f92-a809-96b27f005da2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_d5ee955b-901e-451b-aedb-fc7876aaa403" xlink:href="ebs-20231231.xsd#ebs_SeniorUnsecuredNotesDueAugust2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f3190abf-b926-4f92-a809-96b27f005da2" xlink:to="loc_ebs_SeniorUnsecuredNotesDueAugust2028Member_d5ee955b-901e-451b-aedb-fc7876aaa403" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AmendedCreditAgreementMember_1bdad43b-f884-4e70-a5df-4ffa527d6114" xlink:href="ebs-20231231.xsd#ebs_AmendedCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f3190abf-b926-4f92-a809-96b27f005da2" xlink:to="loc_ebs_AmendedCreditAgreementMember_1bdad43b-f884-4e70-a5df-4ffa527d6114" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ForbearanceAgreementAndAmendmentMember_ea9c31eb-0832-49c3-9054-de6d592730b0" xlink:href="ebs-20231231.xsd#ebs_ForbearanceAgreementAndAmendmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_f3190abf-b926-4f92-a809-96b27f005da2" xlink:to="loc_ebs_ForbearanceAgreementAndAmendmentMember_ea9c31eb-0832-49c3-9054-de6d592730b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_3bd9eddf-e660-4f6f-9439-76d9efda8a57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_3bd9eddf-e660-4f6f-9439-76d9efda8a57" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3bd9eddf-e660-4f6f-9439-76d9efda8a57_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_3bd9eddf-e660-4f6f-9439-76d9efda8a57" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_3bd9eddf-e660-4f6f-9439-76d9efda8a57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d4f82b62-8004-4896-9eda-e6b41fe28f56" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_3bd9eddf-e660-4f6f-9439-76d9efda8a57" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d4f82b62-8004-4896-9eda-e6b41fe28f56" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_ca3d7077-8062-4a0e-915d-6f73c98b3231" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d4f82b62-8004-4896-9eda-e6b41fe28f56" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_ca3d7077-8062-4a0e-915d-6f73c98b3231" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_5c46e64d-0b92-4f20-a091-082e85418a63" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_d4f82b62-8004-4896-9eda-e6b41fe28f56" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_5c46e64d-0b92-4f20-a091-082e85418a63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_srt_RangeAxis_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80" xlink:to="loc_srt_RangeMember_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_cfc5754a-71db-4e3a-a369-2708d91ae6e8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_ba8d6cb0-a3e8-4d59-b8a0-38c64040aa80" xlink:to="loc_srt_RangeMember_cfc5754a-71db-4e3a-a369-2708d91ae6e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_ad0425ed-8aa4-4f70-91d6-40b0f225b176" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_cfc5754a-71db-4e3a-a369-2708d91ae6e8" xlink:to="loc_srt_MaximumMember_ad0425ed-8aa4-4f70-91d6-40b0f225b176" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_36262cf8-b443-48d2-aabe-263e42418b7c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_cfc5754a-71db-4e3a-a369-2708d91ae6e8" xlink:to="loc_srt_MinimumMember_36262cf8-b443-48d2-aabe-263e42418b7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_8ef793d2-d76d-4a50-87e6-22a9bcd061cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_CreditFacilityAxis_8ef793d2-d76d-4a50-87e6-22a9bcd061cb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_8ef793d2-d76d-4a50-87e6-22a9bcd061cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_8ef793d2-d76d-4a50-87e6-22a9bcd061cb" xlink:to="loc_us-gaap_CreditFacilityDomain_8ef793d2-d76d-4a50-87e6-22a9bcd061cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a2e4eaa1-eb8d-4cc5-a61b-aeb402505acb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_8ef793d2-d76d-4a50-87e6-22a9bcd061cb" xlink:to="loc_us-gaap_CreditFacilityDomain_a2e4eaa1-eb8d-4cc5-a61b-aeb402505acb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_9b949aaf-39f9-4746-a5b7-4cf6ef71c7f1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_a2e4eaa1-eb8d-4cc5-a61b-aeb402505acb" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_9b949aaf-39f9-4746-a5b7-4cf6ef71c7f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_TermLoanFacilityMember_42fd78fa-d722-4e8d-9769-d3a9c707f5c6" xlink:href="ebs-20231231.xsd#ebs_TermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_a2e4eaa1-eb8d-4cc5-a61b-aeb402505acb" xlink:to="loc_ebs_TermLoanFacilityMember_42fd78fa-d722-4e8d-9769-d3a9c707f5c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_03777ac9-5827-4110-9ce8-7161569c2a4b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_dcbabf0b-7b61-4d95-a37e-9026e7b58fd4" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_03777ac9-5827-4110-9ce8-7161569c2a4b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_ed0b0fb7-be0f-41cb-9a83-9228d08215a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_03777ac9-5827-4110-9ce8-7161569c2a4b" xlink:to="loc_us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember_ed0b0fb7-be0f-41cb-9a83-9228d08215a7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_c91f38b8-2aa4-4f3f-a35c-57b876551701" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_c91f38b8-2aa4-4f3f-a35c-57b876551701" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_c91f38b8-2aa4-4f3f-a35c-57b876551701_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_c91f38b8-2aa4-4f3f-a35c-57b876551701" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_c91f38b8-2aa4-4f3f-a35c-57b876551701_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_98024731-0738-4439-8208-b44ceabdb117" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_c91f38b8-2aa4-4f3f-a35c-57b876551701" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_98024731-0738-4439-8208-b44ceabdb117" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_TravelHealthBusinessMember_8cc2c390-23e4-416d-9755-475e212a286d" xlink:href="ebs-20231231.xsd#ebs_TravelHealthBusinessMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_98024731-0738-4439-8208-b44ceabdb117" xlink:to="loc_ebs_TravelHealthBusinessMember_8cc2c390-23e4-416d-9755-475e212a286d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtTermsAxis_926848ae-7eae-4b34-b80e-3d864b3d6969" xlink:href="ebs-20231231.xsd#ebs_DebtTermsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_ebs_DebtTermsAxis_926848ae-7eae-4b34-b80e-3d864b3d6969" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtTermsDomain_926848ae-7eae-4b34-b80e-3d864b3d6969_default" xlink:href="ebs-20231231.xsd#ebs_DebtTermsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_ebs_DebtTermsAxis_926848ae-7eae-4b34-b80e-3d864b3d6969" xlink:to="loc_ebs_DebtTermsDomain_926848ae-7eae-4b34-b80e-3d864b3d6969_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:href="ebs-20231231.xsd#ebs_DebtTermsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_ebs_DebtTermsAxis_926848ae-7eae-4b34-b80e-3d864b3d6969" xlink:to="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_FiscalQuartersEndingIn2024Member_6c29a81e-ade4-4906-b888-5f3357b7ddce" xlink:href="ebs-20231231.xsd#ebs_FiscalQuartersEndingIn2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:to="loc_ebs_FiscalQuartersEndingIn2024Member_6c29a81e-ade4-4906-b888-5f3357b7ddce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_FiscalQuartersEndingAfter2024Member_53fe59be-db6c-4fa4-b18f-455cd9721aad" xlink:href="ebs-20231231.xsd#ebs_FiscalQuartersEndingAfter2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:to="loc_ebs_FiscalQuartersEndingAfter2024Member_53fe59be-db6c-4fa4-b18f-455cd9721aad" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UntilMarch312024Member_b195a2e4-c129-4bd9-85e2-24a7bf6ec854" xlink:href="ebs-20231231.xsd#ebs_UntilMarch312024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:to="loc_ebs_UntilMarch312024Member_b195a2e4-c129-4bd9-85e2-24a7bf6ec854" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_FiscalQuartersEndingAfterMarch312024Member_49e711f9-6c4c-4ad8-a3b3-033dcaa53a2a" xlink:href="ebs-20231231.xsd#ebs_FiscalQuartersEndingAfterMarch312024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_DebtTermsDomain_6a421122-9db6-4983-a1ef-7a59ecd9f8ca" xlink:to="loc_ebs_FiscalQuartersEndingAfterMarch312024Member_49e711f9-6c4c-4ad8-a3b3-033dcaa53a2a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_29144f85-5a73-4bcd-a1ff-f04c36565388" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_VariableRateAxis_29144f85-5a73-4bcd-a1ff-f04c36565388" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_29144f85-5a73-4bcd-a1ff-f04c36565388_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_29144f85-5a73-4bcd-a1ff-f04c36565388" xlink:to="loc_us-gaap_VariableRateDomain_29144f85-5a73-4bcd-a1ff-f04c36565388_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_29144f85-5a73-4bcd-a1ff-f04c36565388" xlink:to="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SOFREURIBOROrCDORMember_aa78f4de-f855-4fa4-8f07-a687c4c4d7a5" xlink:href="ebs-20231231.xsd#ebs_SOFREURIBOROrCDORMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:to="loc_ebs_SOFREURIBOROrCDORMember_aa78f4de-f855-4fa4-8f07-a687c4c4d7a5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FederalFundsEffectiveSwapRateMember_e0eb9c1c-4791-43c2-98a8-3737736f55d5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FederalFundsEffectiveSwapRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:to="loc_us-gaap_FederalFundsEffectiveSwapRateMember_e0eb9c1c-4791-43c2-98a8-3737736f55d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SecuredOvernightFinancingRateSOFRMember_36ff91e9-91c4-4778-98c9-f96f35e27d25" xlink:href="ebs-20231231.xsd#ebs_SecuredOvernightFinancingRateSOFRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:to="loc_ebs_SecuredOvernightFinancingRateSOFRMember_36ff91e9-91c4-4778-98c9-f96f35e27d25" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_f7eee53c-827d-4853-972b-cca60610e154" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:to="loc_us-gaap_BaseRateMember_f7eee53c-827d-4853-972b-cca60610e154" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SOFRSONIAAndEurocurrencyMember_aa3bcff7-2cee-467a-b48e-91892e866c66" xlink:href="ebs-20231231.xsd#ebs_SOFRSONIAAndEurocurrencyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_7cd48c14-c125-4882-949a-036b9bdb8892" xlink:to="loc_ebs_SOFRSONIAAndEurocurrencyMember_aa3bcff7-2cee-467a-b48e-91892e866c66" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_8e00472f-de0b-48e3-9573-aed3dfdd6f11" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4ae93383-d8ea-416e-ba10-256905a465d1" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_8e00472f-de0b-48e3-9573-aed3dfdd6f11" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_8e00472f-de0b-48e3-9573-aed3dfdd6f11_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_8e00472f-de0b-48e3-9573-aed3dfdd6f11" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_8e00472f-de0b-48e3-9573-aed3dfdd6f11_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_ea03f39e-95ba-452e-bcd3-a2964bcdba9d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_8e00472f-de0b-48e3-9573-aed3dfdd6f11" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_ea03f39e-95ba-452e-bcd3-a2964bcdba9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_b3342079-71a2-496b-b652-514b1b984e84" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_ea03f39e-95ba-452e-bcd3-a2964bcdba9d" xlink:to="loc_us-gaap_SubsequentEventMember_b3342079-71a2-496b-b652-514b1b984e84" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_252be050-bf15-4950-8b0b-25b6713bcb90" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_LongTermDebt_252be050-bf15-4950-8b0b-25b6713bcb90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsCurrentNet_aca7e2e9-018f-492a-8cae-175838a3683c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DeferredFinanceCostsCurrentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DeferredFinanceCostsCurrentNet_aca7e2e9-018f-492a-8cae-175838a3683c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_bb68f70a-4e68-4a0e-8355-e438c1a0311f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_bb68f70a-4e68-4a0e-8355-e438c1a0311f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_c1b21a52-afb4-4586-8ae5-9cb07775612b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_c1b21a52-afb4-4586-8ae5-9cb07775612b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_1550dce5-2fa4-49ea-b4e6-5dc191cb695a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_1550dce5-2fa4-49ea-b4e6-5dc191cb695a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_c5e5a4bd-f234-4c4f-9785-d16ac596eae2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_c5e5a4bd-f234-4c4f-9785-d16ac596eae2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Cash_be9df071-d883-4ecf-91e3-4f2a35cf21be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Cash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_Cash_be9df071-d883-4ecf-91e3-4f2a35cf21be" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_a1f33a7b-aa69-48e5-9584-7ce803454a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RepaymentsOfLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_RepaymentsOfLongTermDebt_a1f33a7b-aa69-48e5-9584-7ce803454a2d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_8646206a-05b4-41c3-81fa-0556d9a0a52b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPaymentPrincipal_8646206a-05b4-41c3-81fa-0556d9a0a52b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentCovenantInterestCoverageRatioMinimum_c643fed9-8f32-4dcc-beda-dcf4b3a27756" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentCovenantInterestCoverageRatioMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_ebs_DebtInstrumentCovenantInterestCoverageRatioMinimum_c643fed9-8f32-4dcc-beda-dcf4b3a27756" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentCovenantLeverageRatioMaximum_33841d4a-ad84-4546-b7bb-0a749286d9f4" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentCovenantLeverageRatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_ebs_DebtInstrumentCovenantLeverageRatioMaximum_33841d4a-ad84-4546-b7bb-0a749286d9f4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentCovenantConsiderationThreshold_9a678593-05a7-4b26-bb01-0c1fd05dede9" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentCovenantConsiderationThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_ebs_DebtInstrumentCovenantConsiderationThreshold_9a678593-05a7-4b26-bb01-0c1fd05dede9" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e5aa22fa-f10e-411c-a953-4ee0e953d4f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_e5aa22fa-f10e-411c-a953-4ee0e953d4f9" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_5329727b-4070-4f74-a318-d91626930803" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_5329727b-4070-4f74-a318-d91626930803" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentMandatoryPrepaymentThreshold_95346469-a4e2-4789-8d7a-104cee20558f" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentMandatoryPrepaymentThreshold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_ebs_DebtInstrumentMandatoryPrepaymentThreshold_95346469-a4e2-4789-8d7a-104cee20558f" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DebtInstrumentMandatoryPrincipalPrepaymentPercentage_74c7de28-5151-44b0-a911-7fe3f3473b3a" xlink:href="ebs-20231231.xsd#ebs_DebtInstrumentMandatoryPrincipalPrepaymentPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_ebs_DebtInstrumentMandatoryPrincipalPrepaymentPercentage_74c7de28-5151-44b0-a911-7fe3f3473b3a" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount_1e1c8c88-70c9-4ce4-a684-a68a065149ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_2e8c7d43-09e1-4420-a1af-75055c21267a" xlink:to="loc_us-gaap_DebtInstrumentFeeAmount_1e1c8c88-70c9-4ce4-a684-a68a065149ac" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_0108d2e7-7eed-4d98-a205-12d25097a03c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:to="loc_us-gaap_AwardTypeAxis_0108d2e7-7eed-4d98-a205-12d25097a03c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0108d2e7-7eed-4d98-a205-12d25097a03c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_0108d2e7-7eed-4d98-a205-12d25097a03c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0108d2e7-7eed-4d98-a205-12d25097a03c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_68be263d-b969-4b35-8e1c-f19ecede0efa" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_0108d2e7-7eed-4d98-a205-12d25097a03c" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_68be263d-b969-4b35-8e1c-f19ecede0efa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_c0d79b99-2965-4c05-9875-9912ae86eb81" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_68be263d-b969-4b35-8e1c-f19ecede0efa" xlink:to="loc_us-gaap_EmployeeStockOptionMember_c0d79b99-2965-4c05-9875-9912ae86eb81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_c902683a-a9a0-4c69-b73a-5719e3685e7c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_68be263d-b969-4b35-8e1c-f19ecede0efa" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_c902683a-a9a0-4c69-b73a-5719e3685e7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_3b2d32d9-3613-44b0-8f93-acb0c4e9cb27" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_68be263d-b969-4b35-8e1c-f19ecede0efa" xlink:to="loc_us-gaap_PerformanceSharesMember_3b2d32d9-3613-44b0-8f93-acb0c4e9cb27" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_5756f39b-b01c-4070-9d33-fe7cea32781f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:to="loc_us-gaap_PlanNameAxis_5756f39b-b01c-4070-9d33-fe7cea32781f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_5756f39b-b01c-4070-9d33-fe7cea32781f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_5756f39b-b01c-4070-9d33-fe7cea32781f" xlink:to="loc_us-gaap_PlanNameDomain_5756f39b-b01c-4070-9d33-fe7cea32781f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_d829bb18-4df9-4347-82e1-2184d0a5cb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_5756f39b-b01c-4070-9d33-fe7cea32781f" xlink:to="loc_us-gaap_PlanNameDomain_d829bb18-4df9-4347-82e1-2184d0a5cb3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember_9edc7784-02c2-45b7-a931-ce0fbd6e497b" xlink:href="ebs-20231231.xsd#ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_d829bb18-4df9-4347-82e1-2184d0a5cb3c" xlink:to="loc_ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember_9edc7784-02c2-45b7-a931-ce0fbd6e497b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_A2023EquityInducementPlanMember_664b4c2f-77c8-4730-8853-83c504cc2d40" xlink:href="ebs-20231231.xsd#ebs_A2023EquityInducementPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_d829bb18-4df9-4347-82e1-2184d0a5cb3c" xlink:to="loc_ebs_A2023EquityInducementPlanMember_664b4c2f-77c8-4730-8853-83c504cc2d40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_aae6264c-2708-445b-8f8d-691da790842b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:to="loc_srt_RangeAxis_aae6264c-2708-445b-8f8d-691da790842b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_aae6264c-2708-445b-8f8d-691da790842b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_aae6264c-2708-445b-8f8d-691da790842b" xlink:to="loc_srt_RangeMember_aae6264c-2708-445b-8f8d-691da790842b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_854b487e-42bb-4db9-b396-2c40792bfdf1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_aae6264c-2708-445b-8f8d-691da790842b" xlink:to="loc_srt_RangeMember_854b487e-42bb-4db9-b396-2c40792bfdf1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ed1fb5e5-2918-445c-b583-253946c2c64c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_854b487e-42bb-4db9-b396-2c40792bfdf1" xlink:to="loc_srt_MinimumMember_ed1fb5e5-2918-445c-b583-253946c2c64c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_66c576b8-71b9-4f5b-b82d-f83c9e81269a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_854b487e-42bb-4db9-b396-2c40792bfdf1" xlink:to="loc_srt_MaximumMember_66c576b8-71b9-4f5b-b82d-f83c9e81269a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsidiarySaleOfStockAxis_304525ac-a67a-4310-bb9f-5028c37d401b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsidiarySaleOfStockAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:to="loc_us-gaap_SubsidiarySaleOfStockAxis_304525ac-a67a-4310-bb9f-5028c37d401b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_304525ac-a67a-4310-bb9f-5028c37d401b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_304525ac-a67a-4310-bb9f-5028c37d401b" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_304525ac-a67a-4310-bb9f-5028c37d401b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNameOfTransactionDomain_82a511d4-6d09-4757-81c4-6cca990d54b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNameOfTransactionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsidiarySaleOfStockAxis_304525ac-a67a-4310-bb9f-5028c37d401b" xlink:to="loc_us-gaap_SaleOfStockNameOfTransactionDomain_82a511d4-6d09-4757-81c4-6cca990d54b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AtTheMarketOfferingMember_5ca12122-69a4-491e-befd-db3a7e99a8ed" xlink:href="ebs-20231231.xsd#ebs_AtTheMarketOfferingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SaleOfStockNameOfTransactionDomain_82a511d4-6d09-4757-81c4-6cca990d54b4" xlink:to="loc_ebs_AtTheMarketOfferingMember_5ca12122-69a4-491e-befd-db3a7e99a8ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_81200336-f3f3-4a6c-a6bf-c1007cf46fc4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_ad97473f-343b-463a-b3f6-cb762eeeff7f" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_81200336-f3f3-4a6c-a6bf-c1007cf46fc4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_81200336-f3f3-4a6c-a6bf-c1007cf46fc4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_81200336-f3f3-4a6c-a6bf-c1007cf46fc4" xlink:to="loc_us-gaap_EquityComponentDomain_81200336-f3f3-4a6c-a6bf-c1007cf46fc4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_42b8d30c-b340-4e7d-8b65-884c441f8712" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_81200336-f3f3-4a6c-a6bf-c1007cf46fc4" xlink:to="loc_us-gaap_EquityComponentDomain_42b8d30c-b340-4e7d-8b65-884c441f8712" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_935d6344-2b6d-4b26-94ad-b05dabd93fdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_42b8d30c-b340-4e7d-8b65-884c441f8712" xlink:to="loc_us-gaap_TreasuryStockCommonMember_935d6344-2b6d-4b26-94ad-b05dabd93fdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_NumberOfShareBasedEmployeeCompensationPlans_24b9b2a6-7b3d-4f2a-ad89-4f24e823af57" xlink:href="ebs-20231231.xsd#ebs_NumberOfShareBasedEmployeeCompensationPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_NumberOfShareBasedEmployeeCompensationPlans_24b9b2a6-7b3d-4f2a-ad89-4f24e823af57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_ea0a908f-5665-4235-8c5f-214d43a93e7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_ea0a908f-5665-4235-8c5f-214d43a93e7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_15c2571e-391b-46f8-a5eb-18be5266e72d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_15c2571e-391b-46f8-a5eb-18be5266e72d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_fa1293e8-354e-49bd-b7ff-31e11a138eb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_fa1293e8-354e-49bd-b7ff-31e11a138eb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_b4c582ae-5b20-4239-a60b-b7f08de75ccf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_b4c582ae-5b20-4239-a60b-b7f08de75ccf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ExercisePriceOfOptionAsPercentageOfFairMarketValueAtGrantDateMinimum_da00a573-a30d-43ce-a7a0-22505b0468cc" xlink:href="ebs-20231231.xsd#ebs_ExercisePriceOfOptionAsPercentageOfFairMarketValueAtGrantDateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_ExercisePriceOfOptionAsPercentageOfFairMarketValueAtGrantDateMinimum_da00a573-a30d-43ce-a7a0-22505b0468cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_01d06d7b-d0fa-4655-8562-10ceed067b95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_01d06d7b-d0fa-4655-8562-10ceed067b95" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromStockOptionsExercised_3dff6aee-b06f-426b-a4cc-6e8855895170" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProceedsFromStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ProceedsFromStockOptionsExercised_3dff6aee-b06f-426b-a4cc-6e8855895170" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a81e31ef-6c18-4dc3-be66-f2d0de60f251" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_a81e31ef-6c18-4dc3-be66-f2d0de60f251" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ef377b7a-3d9e-4f12-8f48-0a9b0b85234d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_ef377b7a-3d9e-4f12-8f48-0a9b0b85234d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_ceec79f1-9daa-4658-b030-dc1bd650456c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_ceec79f1-9daa-4658-b030-dc1bd650456c" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ShareBasedCompensationArrangementShareBasedPaymentAwardAwardsVestedInPeriodFairValue_06233158-b9bf-4c8f-b0bf-786bfe331a64" xlink:href="ebs-20231231.xsd#ebs_ShareBasedCompensationArrangementShareBasedPaymentAwardAwardsVestedInPeriodFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_ShareBasedCompensationArrangementShareBasedPaymentAwardAwardsVestedInPeriodFairValue_06233158-b9bf-4c8f-b0bf-786bfe331a64" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_123f96f7-5b6e-4086-9ade-e35137f27668" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_123f96f7-5b6e-4086-9ade-e35137f27668" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_666f8253-e83a-4cd7-89b5-9d6fec7141db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_666f8253-e83a-4cd7-89b5-9d6fec7141db" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPayoutPercentage_1f2e34f8-4079-49e8-ab5f-bb4b65fe1158" xlink:href="ebs-20231231.xsd#ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPayoutPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPayoutPercentage_1f2e34f8-4079-49e8-ab5f-bb4b65fe1158" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d90ad595-2e9c-4bb2-9368-c1d8abc69f41" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_d90ad595-2e9c-4bb2-9368-c1d8abc69f41" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_f6b00ca1-7fe9-4be9-9dba-1bffffbbf128" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_f6b00ca1-7fe9-4be9-9dba-1bffffbbf128" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockParOrStatedValuePerShare_5d4e988c-873f-446a-911d-506f7497bef9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_PreferredStockParOrStatedValuePerShare_5d4e988c-873f-446a-911d-506f7497bef9" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_de302779-4737-48e0-97e9-679ffb2890ac" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockParOrStatedValuePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_CommonStockParOrStatedValuePerShare_de302779-4737-48e0-97e9-679ffb2890ac" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_1a28c861-aa0c-4545-a67f-c9b35a8b3f20" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_1a28c861-aa0c-4545-a67f-c9b35a8b3f20" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommonStockNumberOfVotesPerCommonShare_c020b973-8703-4838-a068-612d033f8046" xlink:href="ebs-20231231.xsd#ebs_CommonStockNumberOfVotesPerCommonShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_CommonStockNumberOfVotesPerCommonShare_c020b973-8703-4838-a068-612d033f8046" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SaleOfStockAggregateOfferingAmountMaximum_bc25a4c7-909b-4df1-ac75-71febdd0e70e" xlink:href="ebs-20231231.xsd#ebs_SaleOfStockAggregateOfferingAmountMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_SaleOfStockAggregateOfferingAmountMaximum_bc25a4c7-909b-4df1-ac75-71febdd0e70e" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_dad12895-d8ad-4320-b77a-9474702c0624" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction_dad12895-d8ad-4320-b77a-9474702c0624" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SaleOfStockConsiderationReceivedOnTransactionGross_5ee9e06e-0a88-46f8-848e-b7c6288df984" xlink:href="ebs-20231231.xsd#ebs_SaleOfStockConsiderationReceivedOnTransactionGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_SaleOfStockConsiderationReceivedOnTransactionGross_5ee9e06e-0a88-46f8-848e-b7c6288df984" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SaleOfStockPricePerShare_cf638f07-6fae-4c25-a2d2-0c441cc77062" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SaleOfStockPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_SaleOfStockPricePerShare_cf638f07-6fae-4c25-a2d2-0c441cc77062" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SaleOfStockAmountRemainingAvailableForSaleOfShares_12ad5135-7a4f-46df-9c96-3bd9404149af" xlink:href="ebs-20231231.xsd#ebs_SaleOfStockAmountRemainingAvailableForSaleOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_ebs_SaleOfStockAmountRemainingAvailableForSaleOfShares_12ad5135-7a4f-46df-9c96-3bd9404149af" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_4c99a823-eacd-4954-822d-051d65256b24" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_4c99a823-eacd-4954-822d-051d65256b24" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodValue_26029910-179e-41cc-854f-f834ee0b3f87" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodValue_26029910-179e-41cc-854f-f834ee0b3f87" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_325ae209-31b3-475d-87f9-ec5d768789df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_1beced30-c27d-40e1-9680-2b37f18295f8" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_325ae209-31b3-475d-87f9-ec5d768789df" xlink:type="arc" order="28"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockOptionsValuationAssumptionsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityStockOptionsValuationAssumptionsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockOptionsValuationAssumptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d5b15289-9d6a-46c4-b6bd-878cb669294a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d5b15289-9d6a-46c4-b6bd-878cb669294a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_ce8150d1-7c62-4e1b-a492-53193fae2843" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_d5b15289-9d6a-46c4-b6bd-878cb669294a" xlink:to="loc_us-gaap_AwardTypeAxis_ce8150d1-7c62-4e1b-a492-53193fae2843" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ce8150d1-7c62-4e1b-a492-53193fae2843_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_ce8150d1-7c62-4e1b-a492-53193fae2843" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_ce8150d1-7c62-4e1b-a492-53193fae2843_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f21328bc-1c75-4cb4-9950-12ded107550b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_ce8150d1-7c62-4e1b-a492-53193fae2843" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f21328bc-1c75-4cb4-9950-12ded107550b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_71f2745a-de1d-4ee3-ac8d-78dd982bf2f0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_f21328bc-1c75-4cb4-9950-12ded107550b" xlink:to="loc_us-gaap_EmployeeStockOptionMember_71f2745a-de1d-4ee3-ac8d-78dd982bf2f0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_2ce62ed6-340f-4b8b-8848-64b30b3ef5ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_2ce62ed6-340f-4b8b-8848-64b30b3ef5ec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_c298fe47-f152-417d-9ff9-84ca847edfef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_c298fe47-f152-417d-9ff9-84ca847edfef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_c976be6f-f6c6-415c-9617-a0bd6f16f9db" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_c976be6f-f6c6-415c-9617-a0bd6f16f9db" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_ec00275d-e0b6-450e-b47f-9d692431b924" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_ec00275d-e0b6-450e-b47f-9d692431b924" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_63e9b8eb-2c83-4710-898c-c4135fd7bedf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_63e9b8eb-2c83-4710-898c-c4135fd7bedf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_5c9be72c-2d0e-4fa1-8511-d1fc3ebe47f9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_c90692e2-155e-409c-8a6a-50f04dfad820" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_5c9be72c-2d0e-4fa1-8511-d1fc3ebe47f9" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockOptionsRestrictedStockUnitsandPerformanceStockUnitsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityStockOptionsRestrictedStockUnitsandPerformanceStockUnitsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockOptionsRestrictedStockUnitsandPerformanceStockUnitsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97dea3cd-8bab-4503-a9a1-e43355289928" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97dea3cd-8bab-4503-a9a1-e43355289928" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_34e94ef7-9488-443c-af83-6d0b45af5be9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97dea3cd-8bab-4503-a9a1-e43355289928" xlink:to="loc_us-gaap_PlanNameAxis_34e94ef7-9488-443c-af83-6d0b45af5be9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_34e94ef7-9488-443c-af83-6d0b45af5be9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_34e94ef7-9488-443c-af83-6d0b45af5be9" xlink:to="loc_us-gaap_PlanNameDomain_34e94ef7-9488-443c-af83-6d0b45af5be9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_fb763dce-64ce-462f-8606-41fc387e819e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_34e94ef7-9488-443c-af83-6d0b45af5be9" xlink:to="loc_us-gaap_PlanNameDomain_fb763dce-64ce-462f-8606-41fc387e819e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember_1d15b59d-11aa-4f47-88b2-e44e5ba31e57" xlink:href="ebs-20231231.xsd#ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_fb763dce-64ce-462f-8606-41fc387e819e" xlink:to="loc_ebs_EmergentBiosolutionsInc2006StockIncentivePlanMember_1d15b59d-11aa-4f47-88b2-e44e5ba31e57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_4de83baa-39b5-4033-96b0-4d4932aab5d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_97dea3cd-8bab-4503-a9a1-e43355289928" xlink:to="loc_us-gaap_AwardTypeAxis_4de83baa-39b5-4033-96b0-4d4932aab5d6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4de83baa-39b5-4033-96b0-4d4932aab5d6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_4de83baa-39b5-4033-96b0-4d4932aab5d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4de83baa-39b5-4033-96b0-4d4932aab5d6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_722379ba-4116-42f8-93ba-5af4a5b44e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_4de83baa-39b5-4033-96b0-4d4932aab5d6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_722379ba-4116-42f8-93ba-5af4a5b44e7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember_32ea15fa-4d69-4cb5-97cf-9032b0bd30f5" xlink:href="ebs-20231231.xsd#ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_722379ba-4116-42f8-93ba-5af4a5b44e7b" xlink:to="loc_ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember_32ea15fa-4d69-4cb5-97cf-9032b0bd30f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_d6cd59a3-d96a-4a20-8e93-ec8c94b879dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_d6cd59a3-d96a-4a20-8e93-ec8c94b879dc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_7895e001-3eb5-43b6-88c3-925f91ff7006" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_7895e001-3eb5-43b6-88c3-925f91ff7006" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a3fbd715-32bd-40c8-9798-6adcfe71b5c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_a3fbd715-32bd-40c8-9798-6adcfe71b5c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_5503b0a2-3830-49a4-89de-663c79eabff7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_a8dbc8b8-95c6-4bbb-8a59-b0c6151db94a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_5503b0a2-3830-49a4-89de-663c79eabff7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_d95c1529-0b16-44aa-8b4d-8cdbeb05df6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_e11423de-65ee-4b90-9545-2cfd65cfad2a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_e11423de-65ee-4b90-9545-2cfd65cfad2a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_966e9f8e-1885-4580-a5aa-222e53746c70" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_966e9f8e-1885-4580-a5aa-222e53746c70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_cf96c917-ea4c-44af-8ec5-f493f284859d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_cf96c917-ea4c-44af-8ec5-f493f284859d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_6171656a-7fb2-4d29-a374-a136c1d20bc7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_6171656a-7fb2-4d29-a374-a136c1d20bc7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_f8d5eeb4-0bfb-4d85-a634-9c5ff22b796f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_77ef4f23-c055-4c34-9e1a-fe3b40d9fc18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_f8d5eeb4-0bfb-4d85-a634-9c5ff22b796f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_7bcc739c-d2fb-4a9e-a78d-a8c678195cab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_e8bfd807-e3ae-4668-8d30-4a6eb8bcfaad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_e8bfd807-e3ae-4668-8d30-4a6eb8bcfaad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_f13557ed-6e22-4ee8-bace-8fc8ed25ad42" xlink:href="ebs-20231231.xsd#ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_f13557ed-6e22-4ee8-bace-8fc8ed25ad42" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_63280307-2b34-49cb-87de-7f8b411ae9e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_f13557ed-6e22-4ee8-bace-8fc8ed25ad42" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_63280307-2b34-49cb-87de-7f8b411ae9e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_887fc07a-1a82-4445-81eb-d92b53a3213b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract_f13557ed-6e22-4ee8-bace-8fc8ed25ad42" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_887fc07a-1a82-4445-81eb-d92b53a3213b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_2b6c1668-4784-4deb-8978-7b7b189ed488" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_2b6c1668-4784-4deb-8978-7b7b189ed488" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_d86c6f54-37e7-4ad8-b2bd-0ef2891ac5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_2b6c1668-4784-4deb-8978-7b7b189ed488" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_d86c6f54-37e7-4ad8-b2bd-0ef2891ac5ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_fd63434a-4908-464b-9721-6109e62abc16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_2b6c1668-4784-4deb-8978-7b7b189ed488" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_fd63434a-4908-464b-9721-6109e62abc16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d7d9e517-1e62-4e9b-beda-f36546749600" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_d7d9e517-1e62-4e9b-beda-f36546749600" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ba721a0b-1493-4a1a-ae17-93bfac288596" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_ba721a0b-1493-4a1a-ae17-93bfac288596" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9b80c020-a9ed-425d-acb3-afc2b3505778" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_9b80c020-a9ed-425d-acb3-afc2b3505778" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_2ec78539-f51c-4381-b987-54236a0e0369" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_9dcec7d4-1fb2-416b-b049-8d0cc7996f45" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_2ec78539-f51c-4381-b987-54236a0e0369" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_24df76e8-b6b7-43d5-bb74-17a51e832fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b9a4ea01-c7b8-4588-903b-2d3f8050a317" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_b9a4ea01-c7b8-4588-903b-2d3f8050a317" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_13f13c02-0212-4ac5-9263-a58ae106eaa6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_13f13c02-0212-4ac5-9263-a58ae106eaa6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_b9c13c29-dc7a-4596-981a-7b28cda71ab8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_b9c13c29-dc7a-4596-981a-7b28cda71ab8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_b5efc2c2-5d0f-4823-a851-0faef30346d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_2f1f7782-cffa-42e6-bdd8-186024f67049" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_b5efc2c2-5d0f-4823-a851-0faef30346d7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_326f0df0-adc2-4d90-bafc-cef04439a76b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_4e869582-5c67-4796-a9a3-7ca7e0bca9d0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_4e869582-5c67-4796-a9a3-7ca7e0bca9d0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_47b7b9a2-ed3d-4c61-bf53-cfc829cf32bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueAbstract_4e869582-5c67-4796-a9a3-7ca7e0bca9d0" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstanding_47b7b9a2-ed3d-4c61-bf53-cfc829cf32bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPayoutPercentage_ff827e45-3f11-4e2d-84da-7f10c11cd289" xlink:href="ebs-20231231.xsd#ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPayoutPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_83a155f6-a91a-4c8e-a8d7-67b1410afa38" xlink:to="loc_ebs_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetPayoutPercentage_ff827e45-3f11-4e2d-84da-7f10c11cd289" xlink:type="arc" order="9"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockbasedCompensationExpenseDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityStockbasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityStockbasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_e3dcd921-cc9f-4fa0-87d7-93ac53fca286" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e45d37e0-0a48-4442-91e0-08f28f227a31" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_e3dcd921-cc9f-4fa0-87d7-93ac53fca286" xlink:to="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e45d37e0-0a48-4442-91e0-08f28f227a31" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e45d37e0-0a48-4442-91e0-08f28f227a31" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_62c629f6-b051-4c43-98a8-4f4c0b1df61d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_e5df4170-b66c-48a1-b233-6e4cf7c0d8a4" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_62c629f6-b051-4c43-98a8-4f4c0b1df61d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_b259e022-c49e-4181-a0de-85a9444318dc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_62c629f6-b051-4c43-98a8-4f4c0b1df61d" xlink:to="loc_us-gaap_CostOfSalesMember_b259e022-c49e-4181-a0de-85a9444318dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_ba8e320d-5697-4f5f-8efb-074c65aa99d2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_62c629f6-b051-4c43-98a8-4f4c0b1df61d" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_ba8e320d-5697-4f5f-8efb-074c65aa99d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_393fbd12-b161-4f63-946f-d84682409e9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_62c629f6-b051-4c43-98a8-4f4c0b1df61d" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_393fbd12-b161-4f63-946f-d84682409e9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_efe32b32-2483-4e48-ba68-955108a2fac9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTable_e45d37e0-0a48-4442-91e0-08f28f227a31" xlink:to="loc_srt_ProductOrServiceAxis_efe32b32-2483-4e48-ba68-955108a2fac9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_efe32b32-2483-4e48-ba68-955108a2fac9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_efe32b32-2483-4e48-ba68-955108a2fac9" xlink:to="loc_srt_ProductsAndServicesDomain_efe32b32-2483-4e48-ba68-955108a2fac9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_adaa6c0c-a7b2-4aef-8780-877e8a63ace9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_efe32b32-2483-4e48-ba68-955108a2fac9" xlink:to="loc_srt_ProductsAndServicesDomain_adaa6c0c-a7b2-4aef-8780-877e8a63ace9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductMember_549409ca-7196-4730-9be6-d83e4446f249" xlink:href="ebs-20231231.xsd#ebs_CommercialProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_adaa6c0c-a7b2-4aef-8780-877e8a63ace9" xlink:to="loc_ebs_CommercialProductMember_549409ca-7196-4730-9be6-d83e4446f249" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MedicalCountermeasuresMCMProductMember_e6def31f-9a58-436a-94fc-30d526d81d4c" xlink:href="ebs-20231231.xsd#ebs_MedicalCountermeasuresMCMProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_adaa6c0c-a7b2-4aef-8780-877e8a63ace9" xlink:to="loc_ebs_MedicalCountermeasuresMCMProductMember_e6def31f-9a58-436a-94fc-30d526d81d4c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesMember_d2199dc1-c4b3-4b57-a172-291d5df84d12" xlink:href="ebs-20231231.xsd#ebs_BioservicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_adaa6c0c-a7b2-4aef-8780-877e8a63ace9" xlink:to="loc_ebs_BioservicesMember_d2199dc1-c4b3-4b57-a172-291d5df84d12" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_bd25e04c-8b51-4f83-83c0-e9007be779f2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsLineItems_e3dcd921-cc9f-4fa0-87d7-93ac53fca286" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_bd25e04c-8b51-4f83-83c0-e9007be779f2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityChangesinAccumulatedOtherComprehensiveLossDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityChangesinAccumulatedOtherComprehensiveLossDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityChangesinAccumulatedOtherComprehensiveLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_9b2db5d3-10b5-46e3-9337-596fcc208e4b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_a8db79d6-7d0b-4629-a25b-75e7eefd5306" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_9b2db5d3-10b5-46e3-9337-596fcc208e4b" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_a8db79d6-7d0b-4629-a25b-75e7eefd5306" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f2296446-7c3f-479b-a5d2-16a1dff89b68" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_a8db79d6-7d0b-4629-a25b-75e7eefd5306" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f2296446-7c3f-479b-a5d2-16a1dff89b68" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f2296446-7c3f-479b-a5d2-16a1dff89b68_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f2296446-7c3f-479b-a5d2-16a1dff89b68" xlink:to="loc_us-gaap_EquityComponentDomain_f2296446-7c3f-479b-a5d2-16a1dff89b68_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_a4b1303d-088a-4628-91f5-796428e60fec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f2296446-7c3f-479b-a5d2-16a1dff89b68" xlink:to="loc_us-gaap_EquityComponentDomain_a4b1303d-088a-4628-91f5-796428e60fec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_723a8432-058f-406b-b2ea-f360a436db9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_a4b1303d-088a-4628-91f5-796428e60fec" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_723a8432-058f-406b-b2ea-f360a436db9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_452278f7-7729-48fa-a8a2-8754d13b7e3d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_723a8432-058f-406b-b2ea-f360a436db9b" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_452278f7-7729-48fa-a8a2-8754d13b7e3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_c19de148-41f7-4644-99e8-e2f1618135e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_723a8432-058f-406b-b2ea-f360a436db9b" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_c19de148-41f7-4644-99e8-e2f1618135e4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_2bffa6b7-5a7d-49bf-b981-751da66ff5d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_723a8432-058f-406b-b2ea-f360a436db9b" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_2bffa6b7-5a7d-49bf-b981-751da66ff5d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_9b2db5d3-10b5-46e3-9337-596fcc208e4b" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_3a91bce8-f4d7-44e2-a903-7ef264f88daf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:to="loc_us-gaap_StockholdersEquity_3a91bce8-f4d7-44e2-a903-7ef264f88daf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_f087fc8d-b24d-46de-bea9-e97527ca225b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:to="loc_us-gaap_OciBeforeReclassificationsNetOfTaxAttributableToParent_f087fc8d-b24d-46de-bea9-e97527ca225b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_b2e19341-d0f2-4a9f-99e1-4d2227249de7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_b2e19341-d0f2-4a9f-99e1-4d2227249de7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7a59fc2a-572d-4411-b01b-a1f902c36f8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_6b0f8d1b-342b-45ab-a6a5-a2aa5ab24b65" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_7a59fc2a-572d-4411-b01b-a1f902c36f8d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_21a7863a-b44c-4acc-b287-9eb94847ef3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityTaxEffectsRelatedtoEachComponentofAccumulatedOtherComprehensiveLossIncomeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SharebasedcompensationandstockholdersequityTaxEffectsRelatedtoEachComponentofAccumulatedOtherComprehensiveLossIncomeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SharebasedcompensationandstockholdersequityTaxEffectsRelatedtoEachComponentofAccumulatedOtherComprehensiveLossIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_76107697-6b1a-4cf3-839e-361b7d9cb914" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_8be5f39b-676b-41f4-a9dd-f73eb73c0f6e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_76107697-6b1a-4cf3-839e-361b7d9cb914" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_8be5f39b-676b-41f4-a9dd-f73eb73c0f6e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_f25826c2-a6fe-44d6-8719-07265398e585" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_8be5f39b-676b-41f4-a9dd-f73eb73c0f6e" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_f25826c2-a6fe-44d6-8719-07265398e585" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_f25826c2-a6fe-44d6-8719-07265398e585_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f25826c2-a6fe-44d6-8719-07265398e585" xlink:to="loc_us-gaap_EquityComponentDomain_f25826c2-a6fe-44d6-8719-07265398e585_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_cb150b56-497c-4743-8718-ec56ca66a21f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_f25826c2-a6fe-44d6-8719-07265398e585" xlink:to="loc_us-gaap_EquityComponentDomain_cb150b56-497c-4743-8718-ec56ca66a21f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_4b2f673c-71c8-45b6-86b4-9179daa37434" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_cb150b56-497c-4743-8718-ec56ca66a21f" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember_4b2f673c-71c8-45b6-86b4-9179daa37434" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_99ba6244-2ff7-40d8-a327-5b0db058e6d1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_cb150b56-497c-4743-8718-ec56ca66a21f" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_99ba6244-2ff7-40d8-a327-5b0db058e6d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_5d737692-aee9-4337-a231-2f2ffa24f211" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_cb150b56-497c-4743-8718-ec56ca66a21f" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_5d737692-aee9-4337-a231-2f2ffa24f211" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_43e1d3c5-eab2-4d5e-a7f2-ede7d9cf9e7d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_76107697-6b1a-4cf3-839e-361b7d9cb914" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_43e1d3c5-eab2-4d5e-a7f2-ede7d9cf9e7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_7ccbb094-6d97-427c-a9e8-5b6310d93f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_76107697-6b1a-4cf3-839e-361b7d9cb914" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_7ccbb094-6d97-427c-a9e8-5b6310d93f5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_83fac854-8391-40bb-8396-960a116b5146" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_76107697-6b1a-4cf3-839e-361b7d9cb914" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_83fac854-8391-40bb-8396-960a116b5146" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/RevenuerecognitionNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#RevenuerecognitionNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/RevenuerecognitionNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_3721fcc8-27df-402e-8a69-aed53b2e0350_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:to="loc_srt_NameOfMajorCustomerDomain_3721fcc8-27df-402e-8a69-aed53b2e0350_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:to="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnitedStatesGovernmentMember_bb869e14-b669-45fa-97e3-c874d559c9cf" xlink:href="ebs-20231231.xsd#ebs_UnitedStatesGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_UnitedStatesGovernmentMember_bb869e14-b669-45fa-97e3-c874d559c9cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CustomerTwoMember_502b0afc-66ca-477a-a6a2-e676fe1cbf10" xlink:href="ebs-20231231.xsd#ebs_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_CustomerTwoMember_502b0afc-66ca-477a-a6a2-e676fe1cbf10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_JansenPharmaceuticalsIncMember_6c5c37bd-3a65-4182-815b-5979b3c61ed0" xlink:href="ebs-20231231.xsd#ebs_JansenPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_JansenPharmaceuticalsIncMember_6c5c37bd-3a65-4182-815b-5979b3c61ed0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BARDAMember_9f661b77-4717-4a69-918b-1ed2776bfd13" xlink:href="ebs-20231231.xsd#ebs_BARDAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_BARDAMember_9f661b77-4717-4a69-918b-1ed2776bfd13" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a617bbf4-644b-4789-a4c5-9187bf5aaae2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a617bbf4-644b-4789-a4c5-9187bf5aaae2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_6a073eea-8ef1-4952-9a94-180b71442dd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_6a073eea-8ef1-4952-9a94-180b71442dd9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_41f25527-a499-4066-87b2-ad63502039ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_41f25527-a499-4066-87b2-ad63502039ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_8bf0ffac-be91-42db-821a-17de5e5ce7cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_8bf0ffac-be91-42db-821a-17de5e5ce7cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_ef0d1307-6233-4bac-bf6c-bc1b1c4b8c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_ef0d1307-6233-4bac-bf6c-bc1b1c4b8c4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_073804ef-08af-41b2-8681-e985b0f075c6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:to="loc_srt_SegmentGeographicalDomain_073804ef-08af-41b2-8681-e985b0f075c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:to="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_f307e22e-9607-4658-aee7-812239947536" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:to="loc_country_US_f307e22e-9607-4658-aee7-812239947536" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_6fd8db6c-81f1-4365-a6d8-4c455d6c05d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:to="loc_us-gaap_NonUsMember_6fd8db6c-81f1-4365-a6d8-4c455d6c05d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_9354c98b-d035-444e-8c73-651066db0375_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:to="loc_us-gaap_LeaseContractualTermDomain_9354c98b-d035-444e-8c73-651066db0375_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:to="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ReservationOfManufacturingCapacityMember_31c2d147-8a5e-4043-a758-e7c7f2a71c7d" xlink:href="ebs-20231231.xsd#ebs_ReservationOfManufacturingCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:to="loc_ebs_ReservationOfManufacturingCapacityMember_31c2d147-8a5e-4043-a758-e7c7f2a71c7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AcceleratedExpansionOfFillFinishCapacityMember_f16a28b2-a32b-4ea6-a479-9aef425007b7" xlink:href="ebs-20231231.xsd#ebs_AcceleratedExpansionOfFillFinishCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:to="loc_ebs_AcceleratedExpansionOfFillFinishCapacityMember_f16a28b2-a32b-4ea6-a479-9aef425007b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6699f2a2-de8d-4f69-a13f-449d532817c2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:to="loc_srt_ProductsAndServicesDomain_6699f2a2-de8d-4f69-a13f-449d532817c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:to="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesLeasesMember_c0be17d6-dd3d-4b6c-91c0-eb84a663ad73" xlink:href="ebs-20231231.xsd#ebs_BioservicesLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:to="loc_ebs_BioservicesLeasesMember_c0be17d6-dd3d-4b6c-91c0-eb84a663ad73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ContractsAndGrantsMember_80d77908-55b9-4fa9-ac79-6e84958a0044" xlink:href="ebs-20231231.xsd#ebs_ContractsAndGrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:to="loc_ebs_ContractsAndGrantsMember_80d77908-55b9-4fa9-ac79-6e84958a0044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_99eb1c7f-2298-468c-a12c-6614e032d728" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_99eb1c7f-2298-468c-a12c-6614e032d728" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_d17d525e-ed0c-481b-a624-a31e2efeb2b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_NumberOfReportableSegments_d17d525e-ed0c-481b-a624-a31e2efeb2b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_4fa9f25d-184d-4e77-a5c2-48c4b459acb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_NumberOfOperatingSegments_4fa9f25d-184d-4e77-a5c2-48c4b459acb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_650c4e50-b1a9-434d-996c-16624755450c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_650c4e50-b1a9-434d-996c-16624755450c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_32f88514-edc3-43c5-a237-2611cb48cbdd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_32f88514-edc3-43c5-a237-2611cb48cbdd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_5ba4389a-1e0a-4350-bd50-7bf488e66b3d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_5ba4389a-1e0a-4350-bd50-7bf488e66b3d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_975c9ea4-cc93-430e-8c0c-47108dd34578" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_975c9ea4-cc93-430e-8c0c-47108dd34578" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_f0c11c15-8ff7-40a8-ab4e-99fa5dbdeb9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_f0c11c15-8ff7-40a8-ab4e-99fa5dbdeb9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3a295bfb-d5be-42db-bef9-a7a9a09ec19b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3a295bfb-d5be-42db-bef9-a7a9a09ec19b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_31a23ba0-3dc5-4e56-8b08-be891d9a77a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_31a23ba0-3dc5-4e56-8b08-be891d9a77a2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_09f0e67f-d641-46b4-9b46-7df3e0c91be1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_09f0e67f-d641-46b4-9b46-7df3e0c91be1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_8d7456e9-6158-4509-a200-0f3779cdafad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_8d7456e9-6158-4509-a200-0f3779cdafad" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_97ff830f-653c-4b12-b357-7345717602cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_97ff830f-653c-4b12-b357-7345717602cf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_730b83f3-2428-4a1b-8c29-4bea161119c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_730b83f3-2428-4a1b-8c29-4bea161119c3" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_328deecd-b04d-48d9-80a2-899cd8a24c60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_328deecd-b04d-48d9-80a2-899cd8a24c60" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_7b8889a9-360a-4475-aa96-2d59c6d26fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_7b8889a9-360a-4475-aa96-2d59c6d26fb7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_85ff2546-7d0d-41b2-be54-df1dc106fbb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_85ff2546-7d0d-41b2-be54-df1dc106fbb0" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_0ebcf1e7-9478-467a-bc15-d6e3c603ff59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_0ebcf1e7-9478-467a-bc15-d6e3c603ff59" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetNoncurrent_fbe05050-47ac-43b1-bf61-686ff8c620eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetNetNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetNoncurrent_fbe05050-47ac-43b1-bf61-686ff8c620eb" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_b2db22a4-8ad0-49ea-ad97-9420d5af3af7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_b2db22a4-8ad0-49ea-ad97-9420d5af3af7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_eb5dad55-7677-4e36-9cb4-8652910d1217" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_eb5dad55-7677-4e36-9cb4-8652910d1217" xlink:type="arc" order="19"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/RevenuerecognitionNarrativeDetails_1" xlink:type="simple" xlink:href="ebs-20231231.xsd#RevenuerecognitionNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/RevenuerecognitionNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_3721fcc8-27df-402e-8a69-aed53b2e0350_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:to="loc_srt_NameOfMajorCustomerDomain_3721fcc8-27df-402e-8a69-aed53b2e0350_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_3721fcc8-27df-402e-8a69-aed53b2e0350" xlink:to="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnitedStatesGovernmentMember_bb869e14-b669-45fa-97e3-c874d559c9cf" xlink:href="ebs-20231231.xsd#ebs_UnitedStatesGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_UnitedStatesGovernmentMember_bb869e14-b669-45fa-97e3-c874d559c9cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CustomerTwoMember_502b0afc-66ca-477a-a6a2-e676fe1cbf10" xlink:href="ebs-20231231.xsd#ebs_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_CustomerTwoMember_502b0afc-66ca-477a-a6a2-e676fe1cbf10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_JansenPharmaceuticalsIncMember_6c5c37bd-3a65-4182-815b-5979b3c61ed0" xlink:href="ebs-20231231.xsd#ebs_JansenPharmaceuticalsIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_JansenPharmaceuticalsIncMember_6c5c37bd-3a65-4182-815b-5979b3c61ed0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BARDAMember_9f661b77-4717-4a69-918b-1ed2776bfd13" xlink:href="ebs-20231231.xsd#ebs_BARDAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_686a891c-7606-4c5f-b76d-907f098c5087" xlink:to="loc_ebs_BARDAMember_9f661b77-4717-4a69-918b-1ed2776bfd13" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a617bbf4-644b-4789-a4c5-9187bf5aaae2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a617bbf4-644b-4789-a4c5-9187bf5aaae2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_a617bbf4-644b-4789-a4c5-9187bf5aaae2" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_6a073eea-8ef1-4952-9a94-180b71442dd9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_0367b88a-64bc-4fc3-bb12-b98e8aaf6609" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_6a073eea-8ef1-4952-9a94-180b71442dd9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_41f25527-a499-4066-87b2-ad63502039ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_41f25527-a499-4066-87b2-ad63502039ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_41f25527-a499-4066-87b2-ad63502039ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_8bf0ffac-be91-42db-821a-17de5e5ce7cc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_8bf0ffac-be91-42db-821a-17de5e5ce7cc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicConcentrationRiskMember_ef0d1307-6233-4bac-bf6c-bc1b1c4b8c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeographicConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_1183bf56-9111-4fe2-b2a8-3683f14c5ca5" xlink:to="loc_us-gaap_GeographicConcentrationRiskMember_ef0d1307-6233-4bac-bf6c-bc1b1c4b8c4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_073804ef-08af-41b2-8681-e985b0f075c6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:to="loc_srt_SegmentGeographicalDomain_073804ef-08af-41b2-8681-e985b0f075c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_073804ef-08af-41b2-8681-e985b0f075c6" xlink:to="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_f307e22e-9607-4658-aee7-812239947536" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:to="loc_country_US_f307e22e-9607-4658-aee7-812239947536" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NonUsMember_6fd8db6c-81f1-4365-a6d8-4c455d6c05d6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NonUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_05fd0ff2-8483-47d1-824d-1494a226fcc2" xlink:to="loc_us-gaap_NonUsMember_6fd8db6c-81f1-4365-a6d8-4c455d6c05d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_9354c98b-d035-444e-8c73-651066db0375_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:to="loc_us-gaap_LeaseContractualTermDomain_9354c98b-d035-444e-8c73-651066db0375_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LeaseContractualTermDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LeaseContractualTermAxis_9354c98b-d035-444e-8c73-651066db0375" xlink:to="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ReservationOfManufacturingCapacityMember_31c2d147-8a5e-4043-a758-e7c7f2a71c7d" xlink:href="ebs-20231231.xsd#ebs_ReservationOfManufacturingCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:to="loc_ebs_ReservationOfManufacturingCapacityMember_31c2d147-8a5e-4043-a758-e7c7f2a71c7d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AcceleratedExpansionOfFillFinishCapacityMember_f16a28b2-a32b-4ea6-a479-9aef425007b7" xlink:href="ebs-20231231.xsd#ebs_AcceleratedExpansionOfFillFinishCapacityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LeaseContractualTermDomain_73d8fe71-ee27-4900-b6a8-1b6469784b15" xlink:to="loc_ebs_AcceleratedExpansionOfFillFinishCapacityMember_f16a28b2-a32b-4ea6-a479-9aef425007b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_f0a323a5-fa47-42e2-83b0-acc4fbb2e3ab" xlink:to="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6699f2a2-de8d-4f69-a13f-449d532817c2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:to="loc_srt_ProductsAndServicesDomain_6699f2a2-de8d-4f69-a13f-449d532817c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_6699f2a2-de8d-4f69-a13f-449d532817c2" xlink:to="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesLeasesMember_c0be17d6-dd3d-4b6c-91c0-eb84a663ad73" xlink:href="ebs-20231231.xsd#ebs_BioservicesLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:to="loc_ebs_BioservicesLeasesMember_c0be17d6-dd3d-4b6c-91c0-eb84a663ad73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ContractsAndGrantsMember_80d77908-55b9-4fa9-ac79-6e84958a0044" xlink:href="ebs-20231231.xsd#ebs_ContractsAndGrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6251ca80-fd60-4f21-af8d-56e1f7801a04" xlink:to="loc_ebs_ContractsAndGrantsMember_80d77908-55b9-4fa9-ac79-6e84958a0044" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_d17d525e-ed0c-481b-a624-a31e2efeb2b9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_NumberOfReportableSegments_d17d525e-ed0c-481b-a624-a31e2efeb2b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_4fa9f25d-184d-4e77-a5c2-48c4b459acb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_NumberOfOperatingSegments_4fa9f25d-184d-4e77-a5c2-48c4b459acb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_650c4e50-b1a9-434d-996c-16624755450c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_650c4e50-b1a9-434d-996c-16624755450c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_32f88514-edc3-43c5-a237-2611cb48cbdd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_32f88514-edc3-43c5-a237-2611cb48cbdd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_5ba4389a-1e0a-4350-bd50-7bf488e66b3d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_OtherAssetsNoncurrent_5ba4389a-1e0a-4350-bd50-7bf488e66b3d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_975c9ea4-cc93-430e-8c0c-47108dd34578" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_975c9ea4-cc93-430e-8c0c-47108dd34578" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_f0c11c15-8ff7-40a8-ab4e-99fa5dbdeb9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_f0c11c15-8ff7-40a8-ab4e-99fa5dbdeb9f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3a295bfb-d5be-42db-bef9-a7a9a09ec19b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_3a295bfb-d5be-42db-bef9-a7a9a09ec19b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_31a23ba0-3dc5-4e56-8b08-be891d9a77a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_31a23ba0-3dc5-4e56-8b08-be891d9a77a2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_09f0e67f-d641-46b4-9b46-7df3e0c91be1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths_09f0e67f-d641-46b4-9b46-7df3e0c91be1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_8d7456e9-6158-4509-a200-0f3779cdafad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedTwoYears_8d7456e9-6158-4509-a200-0f3779cdafad" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_97ff830f-653c-4b12-b357-7345717602cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThreeYears_97ff830f-653c-4b12-b357-7345717602cf" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_730b83f3-2428-4a1b-8c29-4bea161119c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFourYears_730b83f3-2428-4a1b-8c29-4bea161119c3" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_328deecd-b04d-48d9-80a2-899cd8a24c60" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedFiveYears_328deecd-b04d-48d9-80a2-899cd8a24c60" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_7b8889a9-360a-4475-aa96-2d59c6d26fb7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceivedThereafter_7b8889a9-360a-4475-aa96-2d59c6d26fb7" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_85ff2546-7d0d-41b2-be54-df1dc106fbb0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_85ff2546-7d0d-41b2-be54-df1dc106fbb0" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_0ebcf1e7-9478-467a-bc15-d6e3c603ff59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_0ebcf1e7-9478-467a-bc15-d6e3c603ff59" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerAssetNetNoncurrent_fbe05050-47ac-43b1-bf61-686ff8c620eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerAssetNetNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ContractWithCustomerAssetNetNoncurrent_fbe05050-47ac-43b1-bf61-686ff8c620eb" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCurrent_b2db22a4-8ad0-49ea-ad97-9420d5af3af7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCurrent_b2db22a4-8ad0-49ea-ad97-9420d5af3af7" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProvisionForDoubtfulAccounts_eb5dad55-7677-4e36-9cb4-8652910d1217" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProvisionForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_4f2ae049-dde2-403d-a32a-238e170352b8" xlink:to="loc_us-gaap_ProvisionForDoubtfulAccounts_eb5dad55-7677-4e36-9cb4-8652910d1217" xlink:type="arc" order="19"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/RevenuerecognitionDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#RevenuerecognitionDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/RevenuerecognitionDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_2c799566-55db-4eaa-8b63-0f60d422bdf8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_2c799566-55db-4eaa-8b63-0f60d422bdf8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_9b60f7fb-cf0f-447d-ba02-80dbcd641740" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_2c799566-55db-4eaa-8b63-0f60d422bdf8" xlink:to="loc_srt_ProductOrServiceAxis_9b60f7fb-cf0f-447d-ba02-80dbcd641740" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_9b60f7fb-cf0f-447d-ba02-80dbcd641740_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_9b60f7fb-cf0f-447d-ba02-80dbcd641740" xlink:to="loc_srt_ProductsAndServicesDomain_9b60f7fb-cf0f-447d-ba02-80dbcd641740_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_9b60f7fb-cf0f-447d-ba02-80dbcd641740" xlink:to="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductMember_32b5811d-e66e-460f-99a5-8a429c6751a0" xlink:href="ebs-20231231.xsd#ebs_CommercialProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:to="loc_ebs_CommercialProductMember_32b5811d-e66e-460f-99a5-8a429c6751a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MedicalCountermeasuresMCMProductMember_151d5f74-da8b-47ac-a7a4-0e8cc335e54f" xlink:href="ebs-20231231.xsd#ebs_MedicalCountermeasuresMCMProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:to="loc_ebs_MedicalCountermeasuresMCMProductMember_151d5f74-da8b-47ac-a7a4-0e8cc335e54f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesMember_d8733611-6197-4568-9486-c424a639e396" xlink:href="ebs-20231231.xsd#ebs_BioservicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:to="loc_ebs_BioservicesMember_d8733611-6197-4568-9486-c424a639e396" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_c3fb4965-91f2-441c-b804-754a939bab7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_BioservicesMember_d8733611-6197-4568-9486-c424a639e396" xlink:to="loc_us-gaap_ServiceMember_c3fb4965-91f2-441c-b804-754a939bab7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BioservicesLeasesMember_8aaa65d8-b7d8-45f0-8c87-ac52a0be5c72" xlink:href="ebs-20231231.xsd#ebs_BioservicesLeasesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_ebs_BioservicesMember_d8733611-6197-4568-9486-c424a639e396" xlink:to="loc_ebs_BioservicesLeasesMember_8aaa65d8-b7d8-45f0-8c87-ac52a0be5c72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ContractsAndGrantsMember_370c5551-6820-44ea-b17d-4e46f0b9fa0a" xlink:href="ebs-20231231.xsd#ebs_ContractsAndGrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_36667d87-e7aa-4e27-a26f-211d775d9ac7" xlink:to="loc_ebs_ContractsAndGrantsMember_370c5551-6820-44ea-b17d-4e46f0b9fa0a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_ca684d5b-818b-470d-b420-ea9121821120" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_2c799566-55db-4eaa-8b63-0f60d422bdf8" xlink:to="loc_srt_MajorCustomersAxis_ca684d5b-818b-470d-b420-ea9121821120" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_ca684d5b-818b-470d-b420-ea9121821120_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_ca684d5b-818b-470d-b420-ea9121821120" xlink:to="loc_srt_NameOfMajorCustomerDomain_ca684d5b-818b-470d-b420-ea9121821120_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_ce9cba2c-1b91-4088-bc8a-e82b1bbc3504" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_ca684d5b-818b-470d-b420-ea9121821120" xlink:to="loc_srt_NameOfMajorCustomerDomain_ce9cba2c-1b91-4088-bc8a-e82b1bbc3504" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnitedStatesGovernmentMember_9b816af0-24b0-4ccc-99f9-26c18bcbdcd6" xlink:href="ebs-20231231.xsd#ebs_UnitedStatesGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_ce9cba2c-1b91-4088-bc8a-e82b1bbc3504" xlink:to="loc_ebs_UnitedStatesGovernmentMember_9b816af0-24b0-4ccc-99f9-26c18bcbdcd6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_NonUnitedStatesGovernmentMember_ddedcf73-812b-48a3-a4a1-e17dff95982b" xlink:href="ebs-20231231.xsd#ebs_NonUnitedStatesGovernmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_ce9cba2c-1b91-4088-bc8a-e82b1bbc3504" xlink:to="loc_ebs_NonUnitedStatesGovernmentMember_ddedcf73-812b-48a3-a4a1-e17dff95982b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_4386edaa-e23a-4a60-b02c-f5fca5ca6616" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_4386edaa-e23a-4a60-b02c-f5fca5ca6616" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_120c7f73-9ec4-4ddb-823b-ec901acec507" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_120c7f73-9ec4-4ddb-823b-ec901acec507" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_d71ff768-3d6b-461e-b261-8d1ef9479d26" xlink:href="ebs-20231231.xsd#ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:to="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_d71ff768-3d6b-461e-b261-8d1ef9479d26" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_144758fc-8873-44cb-9c51-336b0e12fb3a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_e044b21c-4904-477a-825c-4718754cbd40" xlink:to="loc_us-gaap_Revenues_144758fc-8873-44cb-9c51-336b0e12fb3a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/RevenuerecognitionPercentageofProductSalesDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#RevenuerecognitionPercentageofProductSalesDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/RevenuerecognitionPercentageofProductSalesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_77c5d13d-f6a6-47f1-931d-3a18919484da" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_1d309fd3-e567-41e6-9b77-9ce4ac0a8e04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_77c5d13d-f6a6-47f1-931d-3a18919484da" xlink:to="loc_us-gaap_ConcentrationRiskTable_1d309fd3-e567-41e6-9b77-9ce4ac0a8e04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_015231e0-07d7-4da2-85e4-d78fdf3919ce" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_1d309fd3-e567-41e6-9b77-9ce4ac0a8e04" xlink:to="loc_srt_ProductOrServiceAxis_015231e0-07d7-4da2-85e4-d78fdf3919ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_015231e0-07d7-4da2-85e4-d78fdf3919ce_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_015231e0-07d7-4da2-85e4-d78fdf3919ce" xlink:to="loc_srt_ProductsAndServicesDomain_015231e0-07d7-4da2-85e4-d78fdf3919ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_015231e0-07d7-4da2-85e4-d78fdf3919ce" xlink:to="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_NARCANMember_e820ed96-16d8-4c6e-a40c-fde4318b09b5" xlink:href="ebs-20231231.xsd#ebs_NARCANMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:to="loc_ebs_NARCANMember_e820ed96-16d8-4c6e-a40c-fde4318b09b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OtherCommercialProductsMember_2affebd6-a6a7-4173-b09b-ab51fee87be5" xlink:href="ebs-20231231.xsd#ebs_OtherCommercialProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:to="loc_ebs_OtherCommercialProductsMember_2affebd6-a6a7-4173-b09b-ab51fee87be5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AnthraxMCMMember_331df583-667a-4830-aa8e-b3e264b62172" xlink:href="ebs-20231231.xsd#ebs_AnthraxMCMMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:to="loc_ebs_AnthraxMCMMember_331df583-667a-4830-aa8e-b3e264b62172" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SmallpoxMCMMember_57c347a8-c7a4-48fd-b598-d2b9595ac711" xlink:href="ebs-20231231.xsd#ebs_SmallpoxMCMMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:to="loc_ebs_SmallpoxMCMMember_57c347a8-c7a4-48fd-b598-d2b9595ac711" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OtherProductsMember_822de368-c7a2-4b76-95d1-1891b61475b3" xlink:href="ebs-20231231.xsd#ebs_OtherProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_17c002b5-229a-4d11-9d83-76a708232f60" xlink:to="loc_ebs_OtherProductsMember_822de368-c7a2-4b76-95d1-1891b61475b3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3c56ac32-f908-435c-bf3f-e773e89673a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_1d309fd3-e567-41e6-9b77-9ce4ac0a8e04" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3c56ac32-f908-435c-bf3f-e773e89673a7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3c56ac32-f908-435c-bf3f-e773e89673a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3c56ac32-f908-435c-bf3f-e773e89673a7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_3c56ac32-f908-435c-bf3f-e773e89673a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a9c356a8-89a6-4a25-8bde-bba802fe63ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_3c56ac32-f908-435c-bf3f-e773e89673a7" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a9c356a8-89a6-4a25-8bde-bba802fe63ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueProductLineMember_514a3695-3351-4aaf-8cbf-3a689439f866" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SalesRevenueProductLineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a9c356a8-89a6-4a25-8bde-bba802fe63ae" xlink:to="loc_us-gaap_SalesRevenueProductLineMember_514a3695-3351-4aaf-8cbf-3a689439f866" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_91728fe1-5a58-4d3b-8f92-71a4df1928ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_1d309fd3-e567-41e6-9b77-9ce4ac0a8e04" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_91728fe1-5a58-4d3b-8f92-71a4df1928ca" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_91728fe1-5a58-4d3b-8f92-71a4df1928ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_91728fe1-5a58-4d3b-8f92-71a4df1928ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_91728fe1-5a58-4d3b-8f92-71a4df1928ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_ef3eb6a2-3351-450f-98cf-c7d50580874f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_91728fe1-5a58-4d3b-8f92-71a4df1928ca" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_ef3eb6a2-3351-450f-98cf-c7d50580874f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductConcentrationRiskMember_d515586b-5c04-4b61-91a2-1af2291c3b38" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_ef3eb6a2-3351-450f-98cf-c7d50580874f" xlink:to="loc_us-gaap_ProductConcentrationRiskMember_d515586b-5c04-4b61-91a2-1af2291c3b38" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_c060bec2-5b6e-4c33-b579-0dc0c0a9e681" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_77c5d13d-f6a6-47f1-931d-3a18919484da" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_c060bec2-5b6e-4c33-b579-0dc0c0a9e681" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_2924c3e4-0592-4fbb-92bd-09f7493c49be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_8f6ea6ad-cbfa-4533-b58f-f9a5b21ab9e5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_2924c3e4-0592-4fbb-92bd-09f7493c49be" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_8f6ea6ad-cbfa-4533-b58f-f9a5b21ab9e5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_36915cad-3a53-42fb-8caa-24bd985ae493" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_8f6ea6ad-cbfa-4533-b58f-f9a5b21ab9e5" xlink:to="loc_srt_RangeAxis_36915cad-3a53-42fb-8caa-24bd985ae493" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_36915cad-3a53-42fb-8caa-24bd985ae493_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_36915cad-3a53-42fb-8caa-24bd985ae493" xlink:to="loc_srt_RangeMember_36915cad-3a53-42fb-8caa-24bd985ae493_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_7f37500c-56b0-4a3c-a2dc-9b3352a717d6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_36915cad-3a53-42fb-8caa-24bd985ae493" xlink:to="loc_srt_RangeMember_7f37500c-56b0-4a3c-a2dc-9b3352a717d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_2b4900af-cd5a-4032-97c0-f232e0f46e24" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7f37500c-56b0-4a3c-a2dc-9b3352a717d6" xlink:to="loc_srt_MinimumMember_2b4900af-cd5a-4032-97c0-f232e0f46e24" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_fb09721f-d200-4543-9f22-9007fee52ff7" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_7f37500c-56b0-4a3c-a2dc-9b3352a717d6" xlink:to="loc_srt_MaximumMember_fb09721f-d200-4543-9f22-9007fee52ff7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_eb49c590-29b4-461b-87fa-79f148d1840e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRemainingLeaseTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_2924c3e4-0592-4fbb-92bd-09f7493c49be" xlink:to="loc_us-gaap_LesseeOperatingLeaseRemainingLeaseTerm_eb49c590-29b4-461b-87fa-79f148d1840e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_23482494-0863-4b36-a4be-a2935ffdb6ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_2924c3e4-0592-4fbb-92bd-09f7493c49be" xlink:to="loc_us-gaap_LesseeOperatingLeaseRenewalTerm_23482494-0863-4b36-a4be-a2935ffdb6ed" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/IncometaxesNarrativeDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#IncometaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/IncometaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_4e569499-f17f-43a3-9ebe-be696fde3e5e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_4e569499-f17f-43a3-9ebe-be696fde3e5e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_289b811d-fec2-4c55-abda-8f4aa93eff67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_4e569499-f17f-43a3-9ebe-be696fde3e5e" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_289b811d-fec2-4c55-abda-8f4aa93eff67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_289b811d-fec2-4c55-abda-8f4aa93eff67_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_289b811d-fec2-4c55-abda-8f4aa93eff67" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_289b811d-fec2-4c55-abda-8f4aa93eff67_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_602882cf-d67d-4282-848d-b5e243308641" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_289b811d-fec2-4c55-abda-8f4aa93eff67" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_602882cf-d67d-4282-848d-b5e243308641" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_8b56f6a8-27dc-4f64-827d-e7174e0e9c23" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_602882cf-d67d-4282-848d-b5e243308641" xlink:to="loc_us-gaap_DomesticCountryMember_8b56f6a8-27dc-4f64-827d-e7174e0e9c23" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_359924b2-5a5d-4c2a-8436-561e0fd71831" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_602882cf-d67d-4282-848d-b5e243308641" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_359924b2-5a5d-4c2a-8436-561e0fd71831" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCountryMember_3f3ca23d-40da-468d-8413-220faf42b713" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ForeignCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_602882cf-d67d-4282-848d-b5e243308641" xlink:to="loc_us-gaap_ForeignCountryMember_3f3ca23d-40da-468d-8413-220faf42b713" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAxis_197c0cb1-9135-4f9c-b288-5f4e55b6ca76" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxCreditCarryforwardAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_4e569499-f17f-43a3-9ebe-be696fde3e5e" xlink:to="loc_us-gaap_TaxCreditCarryforwardAxis_197c0cb1-9135-4f9c-b288-5f4e55b6ca76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_197c0cb1-9135-4f9c-b288-5f4e55b6ca76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_197c0cb1-9135-4f9c-b288-5f4e55b6ca76" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_197c0cb1-9135-4f9c-b288-5f4e55b6ca76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardNameDomain_b85674b2-62ee-454b-b7a7-59b50466ebb2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxCreditCarryforwardNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TaxCreditCarryforwardAxis_197c0cb1-9135-4f9c-b288-5f4e55b6ca76" xlink:to="loc_us-gaap_TaxCreditCarryforwardNameDomain_b85674b2-62ee-454b-b7a7-59b50466ebb2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchMember_7963413b-1fe4-4c34-97f5-18e8d6f8c960" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TaxCreditCarryforwardNameDomain_b85674b2-62ee-454b-b7a7-59b50466ebb2" xlink:to="loc_us-gaap_ResearchMember_7963413b-1fe4-4c34-97f5-18e8d6f8c960" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_32884107-f4ef-455b-a677-2fbe5626bd5d" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_4e569499-f17f-43a3-9ebe-be696fde3e5e" xlink:to="loc_srt_StatementGeographicalAxis_32884107-f4ef-455b-a677-2fbe5626bd5d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_32884107-f4ef-455b-a677-2fbe5626bd5d_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_32884107-f4ef-455b-a677-2fbe5626bd5d" xlink:to="loc_srt_SegmentGeographicalDomain_32884107-f4ef-455b-a677-2fbe5626bd5d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_4b6d9d0a-1f7c-4aad-ae91-f8279274ad54" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_32884107-f4ef-455b-a677-2fbe5626bd5d" xlink:to="loc_srt_SegmentGeographicalDomain_4b6d9d0a-1f7c-4aad-ae91-f8279274ad54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CA_191311a4-083a-4ed3-81d2-2618467cd0bd" xlink:href="https://xbrl.sec.gov/stpr/2023/stpr-2023.xsd#stpr_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_4b6d9d0a-1f7c-4aad-ae91-f8279274ad54" xlink:to="loc_stpr_CA_191311a4-083a-4ed3-81d2-2618467cd0bd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseIncludingCumulativeTranslationAdjustmentAmount_847ae571-ce68-4225-9147-0aa4e51a8d0c" xlink:href="ebs-20231231.xsd#ebs_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseIncludingCumulativeTranslationAdjustmentAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_ebs_ValuationAllowanceDeferredTaxAssetIncreaseDecreaseIncludingCumulativeTranslationAdjustmentAmount_847ae571-ce68-4225-9147-0aa4e51a8d0c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_DeferredTaxLiabilitiesForeignWithholdingTax_c3f1ef11-6b3c-4fca-a0d7-2121d9070b64" xlink:href="ebs-20231231.xsd#ebs_DeferredTaxLiabilitiesForeignWithholdingTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_ebs_DeferredTaxLiabilitiesForeignWithholdingTax_c3f1ef11-6b3c-4fca-a0d7-2121d9070b64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_6b9cb206-93ef-4992-9ac6-ad69f70672a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_OperatingLossCarryforwards_6b9cb206-93ef-4992-9ac6-ad69f70672a3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OperatingLossCarryforwardsSubjectToExpiration_17448cd4-09b8-42ea-a006-2a02d995d9ad" xlink:href="ebs-20231231.xsd#ebs_OperatingLossCarryforwardsSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_ebs_OperatingLossCarryforwardsSubjectToExpiration_17448cd4-09b8-42ea-a006-2a02d995d9ad" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OperatingLossCarryforwardsNotSubjectToExpiration_d9471840-a979-4dbf-bac4-48c5add2d769" xlink:href="ebs-20231231.xsd#ebs_OperatingLossCarryforwardsNotSubjectToExpiration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_ebs_OperatingLossCarryforwardsNotSubjectToExpiration_d9471840-a979-4dbf-bac4-48c5add2d769" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TaxCreditCarryforwardAmount_e3aedced-1c23-4976-9438-e5e6114d3bbe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TaxCreditCarryforwardAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_TaxCreditCarryforwardAmount_e3aedced-1c23-4976-9438-e5e6114d3bbe" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_5514279b-c36a-4bf1-84ba-b4ab7b69b9c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount_5514279b-c36a-4bf1-84ba-b4ab7b69b9c4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_6bec7aa4-9656-4344-b2c7-1aa9df319730" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EffectiveIncomeTaxRateContinuingOperations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateContinuingOperations_6bec7aa4-9656-4344-b2c7-1aa9df319730" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_UnrecognizedTaxBenefitsNoncurrent_8ffddd3e-aa78-4222-802e-3b3523552227" xlink:href="ebs-20231231.xsd#ebs_UnrecognizedTaxBenefitsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_ebs_UnrecognizedTaxBenefitsNoncurrent_8ffddd3e-aa78-4222-802e-3b3523552227" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefits_489dc485-b0e4-4c21-9c67-8f968fafcdb4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_UnrecognizedTaxBenefits_489dc485-b0e4-4c21-9c67-8f968fafcdb4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_64926800-b989-4059-a758-24b31e154ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations_64926800-b989-4059-a758-24b31e154ff3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_3e66d2d0-a19e-48e2-a389-6560ff49ddfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued_3e66d2d0-a19e-48e2-a389-6560ff49ddfc" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_d7de6914-3859-4424-8fae-b965456e6c9f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_cbb98f86-7193-4a1f-80ac-3422cbf6a4e4" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestExpense_d7de6914-3859-4424-8fae-b965456e6c9f" xlink:type="arc" order="12"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_376f50f4-1057-4a6c-8152-0adb3e9b726a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_376f50f4-1057-4a6c-8152-0adb3e9b726a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_376f50f4-1057-4a6c-8152-0adb3e9b726a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_376f50f4-1057-4a6c-8152-0adb3e9b726a" xlink:to="loc_us-gaap_SegmentDomain_376f50f4-1057-4a6c-8152-0adb3e9b726a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_b2a3602c-e582-453e-9b8d-9b53826d3d59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_376f50f4-1057-4a6c-8152-0adb3e9b726a" xlink:to="loc_us-gaap_SegmentDomain_b2a3602c-e582-453e-9b8d-9b53826d3d59" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductsSegmentMember_cbb13ddb-8c9e-43d5-9f7e-35abf8ad5268" xlink:href="ebs-20231231.xsd#ebs_CommercialProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b2a3602c-e582-453e-9b8d-9b53826d3d59" xlink:to="loc_ebs_CommercialProductsSegmentMember_cbb13ddb-8c9e-43d5-9f7e-35abf8ad5268" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MCMProductsSegmentMember_5be19b26-127c-4f55-8287-6e0bcec6c04b" xlink:href="ebs-20231231.xsd#ebs_MCMProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b2a3602c-e582-453e-9b8d-9b53826d3d59" xlink:to="loc_ebs_MCMProductsSegmentMember_5be19b26-127c-4f55-8287-6e0bcec6c04b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ServicesSegmentMember_203275d9-f24e-4c53-b0e8-7e8a3e5331a6" xlink:href="ebs-20231231.xsd#ebs_ServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_b2a3602c-e582-453e-9b8d-9b53826d3d59" xlink:to="loc_ebs_ServicesSegmentMember_203275d9-f24e-4c53-b0e8-7e8a3e5331a6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e5187d25-0efa-4edd-88ea-6fe66614fb16" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:to="loc_srt_ProductOrServiceAxis_e5187d25-0efa-4edd-88ea-6fe66614fb16" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e5187d25-0efa-4edd-88ea-6fe66614fb16_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e5187d25-0efa-4edd-88ea-6fe66614fb16" xlink:to="loc_srt_ProductsAndServicesDomain_e5187d25-0efa-4edd-88ea-6fe66614fb16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_77cdc7c5-7f3a-4222-9248-c5a6ca86765c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e5187d25-0efa-4edd-88ea-6fe66614fb16" xlink:to="loc_srt_ProductsAndServicesDomain_77cdc7c5-7f3a-4222-9248-c5a6ca86765c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ContractsAndGrantsMember_1d366b39-9b26-43eb-a7b3-c7bb910c08b9" xlink:href="ebs-20231231.xsd#ebs_ContractsAndGrantsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_77cdc7c5-7f3a-4222-9248-c5a6ca86765c" xlink:to="loc_ebs_ContractsAndGrantsMember_1d366b39-9b26-43eb-a7b3-c7bb910c08b9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_1c14b8ba-fe35-419b-924d-e22b222890c1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:to="loc_srt_MajorCustomersAxis_1c14b8ba-fe35-419b-924d-e22b222890c1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_1c14b8ba-fe35-419b-924d-e22b222890c1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_1c14b8ba-fe35-419b-924d-e22b222890c1" xlink:to="loc_srt_NameOfMajorCustomerDomain_1c14b8ba-fe35-419b-924d-e22b222890c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_5ff95b33-b7e9-462f-9e0b-2fb1cd80ccda" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_1c14b8ba-fe35-419b-924d-e22b222890c1" xlink:to="loc_srt_NameOfMajorCustomerDomain_5ff95b33-b7e9-462f-9e0b-2fb1cd80ccda" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_BARDAMember_e9c9d48b-a26c-4143-9e48-ef6df12f6da1" xlink:href="ebs-20231231.xsd#ebs_BARDAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_5ff95b33-b7e9-462f-9e0b-2fb1cd80ccda" xlink:to="loc_ebs_BARDAMember_e9c9d48b-a26c-4143-9e48-ef6df12f6da1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_72babbaf-34a1-4c3b-9ac9-8d89a960c044" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_d3b835da-fe1e-41c6-ba16-3dc093a1d39b" xlink:to="loc_srt_ConsolidationItemsAxis_72babbaf-34a1-4c3b-9ac9-8d89a960c044" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_72babbaf-34a1-4c3b-9ac9-8d89a960c044_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_72babbaf-34a1-4c3b-9ac9-8d89a960c044" xlink:to="loc_srt_ConsolidationItemsDomain_72babbaf-34a1-4c3b-9ac9-8d89a960c044_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_799ca22e-b7da-4100-bed4-a6664b7a25ee" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_72babbaf-34a1-4c3b-9ac9-8d89a960c044" xlink:to="loc_srt_ConsolidationItemsDomain_799ca22e-b7da-4100-bed4-a6664b7a25ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_8132a1cc-14e2-417c-8834-3c4786b6241f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_799ca22e-b7da-4100-bed4-a6664b7a25ee" xlink:to="loc_us-gaap_OperatingSegmentsMember_8132a1cc-14e2-417c-8834-3c4786b6241f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_ee28e980-9854-4ccd-8b5e-5b901f5d133a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_799ca22e-b7da-4100-bed4-a6664b7a25ee" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_ee28e980-9854-4ccd-8b5e-5b901f5d133a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_03569d59-155e-4137-b3f9-7222e3368153" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_RevenuesAbstract_03569d59-155e-4137-b3f9-7222e3368153" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_25d812c9-bd11-47b8-9893-e6e086f070b1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_03569d59-155e-4137-b3f9-7222e3368153" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_25d812c9-bd11-47b8-9893-e6e086f070b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_dcea717a-d1b5-4ba3-80f7-3a4437d0ea99" xlink:href="ebs-20231231.xsd#ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_03569d59-155e-4137-b3f9-7222e3368153" xlink:to="loc_ebs_OperatingLeaseLeaseIncomeAndRevenueFromContractWithCustomerExcludingAssessedTax_dcea717a-d1b5-4ba3-80f7-3a4437d0ea99" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_146d132a-963a-41a1-ab72-63861fe9f765" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_03569d59-155e-4137-b3f9-7222e3368153" xlink:to="loc_us-gaap_Revenues_146d132a-963a-41a1-ab72-63861fe9f765" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSoldAbstract_463adbfc-6e55-4a19-a667-29f93b9dcf3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSoldAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSoldAbstract_463adbfc-6e55-4a19-a667-29f93b9dcf3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_6f0439d6-4a8e-4cf8-8fc2-fdaaa23fc872" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostOfGoodsAndServicesSoldAbstract_463adbfc-6e55-4a19-a667-29f93b9dcf3f" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_6f0439d6-4a8e-4cf8-8fc2-fdaaa23fc872" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossProfit_3fee109f-db3d-420e-8e9c-da3841d5562c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GrossProfit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_GrossProfit_3fee109f-db3d-420e-8e9c-da3841d5562c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_GrossProfitPercentage_366f4179-3d91-43a8-8397-03a976bcc709" xlink:href="ebs-20231231.xsd#ebs_GrossProfitPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_ebs_GrossProfitPercentage_366f4179-3d91-43a8-8397-03a976bcc709" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_AdjustedGrossMargin_19252944-473d-4d16-9a93-026149ecd9b3" xlink:href="ebs-20231231.xsd#ebs_AdjustedGrossMargin"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_ebs_AdjustedGrossMargin_19252944-473d-4d16-9a93-026149ecd9b3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_8e61f1d4-cdc0-418d-b11e-58bda60b343a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseLeaseIncomeLeasePayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncomeLeasePayments_8e61f1d4-cdc0-418d-b11e-58bda60b343a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_9682cc7b-d28d-4de8-83fd-3a7b3c1a3d86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_RestructuringCharges_9682cc7b-d28d-4de8-83fd-3a7b3c1a3d86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_InventoryStepUp_b08ef398-7b79-44b4-890c-4558fa305e89" xlink:href="ebs-20231231.xsd#ebs_InventoryStepUp"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_ebs_InventoryStepUp_b08ef398-7b79-44b4-890c-4558fa305e89" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_549f216e-a39e-4287-8324-894f0aae01d7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_549f216e-a39e-4287-8324-894f0aae01d7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_0d789d76-b0a5-4b5a-993f-a84c159d933b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_0d789d76-b0a5-4b5a-993f-a84c159d933b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_56bfcc01-a867-4a58-8de9-3780118910d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_56bfcc01-a867-4a58-8de9-3780118910d9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_8a1abd27-1878-4b10-8a5d-6b6abb1ba2e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_8a1abd27-1878-4b10-8a5d-6b6abb1ba2e4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_5d8802e4-ea77-42e2-836a-a81ea036a39e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_5d8802e4-ea77-42e2-836a-a81ea036a39e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_8ea5051d-2d94-4658-8a30-8c81b6a31c6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_8ea5051d-2d94-4658-8a30-8c81b6a31c6b" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_19eb398d-0c2a-46a0-b3df-18c5b0cbbd00" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_InterestExpense_19eb398d-0c2a-46a0-b3df-18c5b0cbbd00" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnSaleOfBusiness_eb19343e-9677-4e2a-8f5c-687818f6f523" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainLossOnSaleOfBusiness"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_GainLossOnSaleOfBusiness_eb19343e-9677-4e2a-8f5c-687818f6f523" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_2b85c9ae-8009-44cc-a104-a062a316f63c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingOtherSignificantReconcilingItemConsolidatedAbstract_584c8365-7b96-48a8-ab63-cec468e57c95" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_2b85c9ae-8009-44cc-a104-a062a316f63c" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b6410c6b-84d9-4464-97be-1026e6ebbf6d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_0e9a5fde-4c77-4a11-8748-6c04a7148d7b" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_b6410c6b-84d9-4464-97be-1026e6ebbf6d" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SegmentInformationScheduleofSegmentReportingInformationbySegmentDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SegmentInformationScheduleofSegmentReportingInformationbySegmentDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SegmentInformationScheduleofSegmentReportingInformationbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_8de4ca2d-f367-4d16-ac10-fb51a97399b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51b7d2b0-8d2d-41cc-bba4-295f2fffbac7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8de4ca2d-f367-4d16-ac10-fb51a97399b5" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51b7d2b0-8d2d-41cc-bba4-295f2fffbac7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_8d870430-148a-416c-9702-23b9186c51b4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51b7d2b0-8d2d-41cc-bba4-295f2fffbac7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_8d870430-148a-416c-9702-23b9186c51b4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8d870430-148a-416c-9702-23b9186c51b4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8d870430-148a-416c-9702-23b9186c51b4" xlink:to="loc_us-gaap_SegmentDomain_8d870430-148a-416c-9702-23b9186c51b4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_c24742ad-850c-40bf-89f6-1ff60c81de0f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_8d870430-148a-416c-9702-23b9186c51b4" xlink:to="loc_us-gaap_SegmentDomain_c24742ad-850c-40bf-89f6-1ff60c81de0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_MCMProductsSegmentMember_ae1a07db-9b2c-4f22-b042-48e76fdbae1d" xlink:href="ebs-20231231.xsd#ebs_MCMProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c24742ad-850c-40bf-89f6-1ff60c81de0f" xlink:to="loc_ebs_MCMProductsSegmentMember_ae1a07db-9b2c-4f22-b042-48e76fdbae1d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_CommercialProductsSegmentMember_7020feaa-fe46-42e9-97f5-e133c3bb1889" xlink:href="ebs-20231231.xsd#ebs_CommercialProductsSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c24742ad-850c-40bf-89f6-1ff60c81de0f" xlink:to="loc_ebs_CommercialProductsSegmentMember_7020feaa-fe46-42e9-97f5-e133c3bb1889" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_ServicesSegmentMember_a46fc306-0886-4a20-8251-97a1825f6d5e" xlink:href="ebs-20231231.xsd#ebs_ServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_c24742ad-850c-40bf-89f6-1ff60c81de0f" xlink:to="loc_ebs_ServicesSegmentMember_a46fc306-0886-4a20-8251-97a1825f6d5e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_1143644e-d46b-44ad-8a45-4772b9b5bfb4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_51b7d2b0-8d2d-41cc-bba4-295f2fffbac7" xlink:to="loc_srt_ConsolidationItemsAxis_1143644e-d46b-44ad-8a45-4772b9b5bfb4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_1143644e-d46b-44ad-8a45-4772b9b5bfb4_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_1143644e-d46b-44ad-8a45-4772b9b5bfb4" xlink:to="loc_srt_ConsolidationItemsDomain_1143644e-d46b-44ad-8a45-4772b9b5bfb4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ac3d137d-1709-4f90-9d5c-30c1c06d246f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_1143644e-d46b-44ad-8a45-4772b9b5bfb4" xlink:to="loc_srt_ConsolidationItemsDomain_ac3d137d-1709-4f90-9d5c-30c1c06d246f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_81ddaabc-59c7-4d4a-9d20-61de39eb47cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ac3d137d-1709-4f90-9d5c-30c1c06d246f" xlink:to="loc_us-gaap_OperatingSegmentsMember_81ddaabc-59c7-4d4a-9d20-61de39eb47cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_cc11f7b1-10d4-44b4-b978-dfe85635e8a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ac3d137d-1709-4f90-9d5c-30c1c06d246f" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_cc11f7b1-10d4-44b4-b978-dfe85635e8a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Depreciation_74e96b03-05c3-467f-89b2-ac91c5aaa786" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Depreciation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_8de4ca2d-f367-4d16-ac10-fb51a97399b5" xlink:to="loc_us-gaap_Depreciation_74e96b03-05c3-467f-89b2-ac91c5aaa786" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SegmentInformationRevenuefromExternalCustomersbyGeographicAreasDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SegmentInformationRevenuefromExternalCustomersbyGeographicAreasDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SegmentInformationRevenuefromExternalCustomersbyGeographicAreasDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_9abc4cf8-c096-4aca-bcf8-206b290953a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_3da44fd8-e007-4103-99c1-e5e6ca828a18" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9abc4cf8-c096-4aca-bcf8-206b290953a0" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_3da44fd8-e007-4103-99c1-e5e6ca828a18" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ab26d1de-f716-4330-9b04-3803a27159d9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_3da44fd8-e007-4103-99c1-e5e6ca828a18" xlink:to="loc_srt_StatementGeographicalAxis_ab26d1de-f716-4330-9b04-3803a27159d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ab26d1de-f716-4330-9b04-3803a27159d9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ab26d1de-f716-4330-9b04-3803a27159d9" xlink:to="loc_srt_SegmentGeographicalDomain_ab26d1de-f716-4330-9b04-3803a27159d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_73706b37-5d5f-4b47-9199-04ee2b039503" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ab26d1de-f716-4330-9b04-3803a27159d9" xlink:to="loc_srt_SegmentGeographicalDomain_73706b37-5d5f-4b47-9199-04ee2b039503" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_0b62c707-cf28-4382-a736-55efbf09b14e" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_73706b37-5d5f-4b47-9199-04ee2b039503" xlink:to="loc_country_US_0b62c707-cf28-4382-a736-55efbf09b14e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_6994f5f9-8868-4876-867d-be22ac0ba7b7" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_73706b37-5d5f-4b47-9199-04ee2b039503" xlink:to="loc_country_CA_6994f5f9-8868-4876-867d-be22ac0ba7b7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OtherGeographicalAreaMember_4a3904b6-f835-4074-9be6-278e8e18d439" xlink:href="ebs-20231231.xsd#ebs_OtherGeographicalAreaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_73706b37-5d5f-4b47-9199-04ee2b039503" xlink:to="loc_ebs_OtherGeographicalAreaMember_4a3904b6-f835-4074-9be6-278e8e18d439" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_602c65a1-a9c0-40f6-96bd-b1c4c845efe7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_9abc4cf8-c096-4aca-bcf8-206b290953a0" xlink:to="loc_us-gaap_Revenues_602c65a1-a9c0-40f6-96bd-b1c4c845efe7" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/SegmentInformationLongLivedAssetsbyGeographicAreasDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#SegmentInformationLongLivedAssetsbyGeographicAreasDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/SegmentInformationLongLivedAssetsbyGeographicAreasDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_cfc92773-e80d-4b48-9419-e50a10339703" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_09fb9d47-1a89-4c85-8974-aef28cfbd002" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_cfc92773-e80d-4b48-9419-e50a10339703" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_09fb9d47-1a89-4c85-8974-aef28cfbd002" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_2159ef28-dc0f-4c1b-bf9f-22f7c120af38" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_09fb9d47-1a89-4c85-8974-aef28cfbd002" xlink:to="loc_srt_StatementGeographicalAxis_2159ef28-dc0f-4c1b-bf9f-22f7c120af38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_2159ef28-dc0f-4c1b-bf9f-22f7c120af38_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_2159ef28-dc0f-4c1b-bf9f-22f7c120af38" xlink:to="loc_srt_SegmentGeographicalDomain_2159ef28-dc0f-4c1b-bf9f-22f7c120af38_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_2159ef28-dc0f-4c1b-bf9f-22f7c120af38" xlink:to="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_734134b9-96d5-42f5-8c8d-7f8232435c9c" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:to="loc_country_US_734134b9-96d5-42f5-8c8d-7f8232435c9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CH_eedadce9-9092-4d1b-9f63-b813cf90ac81" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:to="loc_country_CH_eedadce9-9092-4d1b-9f63-b813cf90ac81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CA_1b101942-8c11-4083-aa59-0034bc582e1b" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_CA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:to="loc_country_CA_1b101942-8c11-4083-aa59-0034bc582e1b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_OtherGeographicalAreaMember_3861465f-23e6-43ef-823c-c03ccf174921" xlink:href="ebs-20231231.xsd#ebs_OtherGeographicalAreaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_a3db6b83-ea53-428d-ada5-4dab63350012" xlink:to="loc_ebs_OtherGeographicalAreaMember_3861465f-23e6-43ef-823c-c03ccf174921" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_07eb6a31-3d56-4b20-be78-dfe0ce34c73f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_cfc92773-e80d-4b48-9419-e50a10339703" xlink:to="loc_us-gaap_NoncurrentAssets_07eb6a31-3d56-4b20-be78-dfe0ce34c73f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://emergentbiosolutions.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="simple" xlink:href="ebs-20231231.xsd#ScheduleIIValuationandQualifyingAccountsDetails"/>
  <link:definitionLink xlink:role="http://emergentbiosolutions.com/role/ScheduleIIValuationandQualifyingAccountsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_b7b8d06d-9e1c-4189-af39-732c33632bc8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ValuationAndQualifyingAccountsDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_fc46b161-a8a7-407a-81dc-8780ef9eefa4" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ValuationAndQualifyingAccountsDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_b7b8d06d-9e1c-4189-af39-732c33632bc8" xlink:to="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_fc46b161-a8a7-407a-81dc-8780ef9eefa4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_6f692257-7131-4278-94f7-01117bc75c97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureTable_fc46b161-a8a7-407a-81dc-8780ef9eefa4" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_6f692257-7131-4278-94f7-01117bc75c97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_6f692257-7131-4278-94f7-01117bc75c97_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_6f692257-7131-4278-94f7-01117bc75c97" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_6f692257-7131-4278-94f7-01117bc75c97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDomain_6cb5854e-3fa4-431d-ae66-0925c3fc284f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesTypeAxis_6f692257-7131-4278-94f7-01117bc75c97" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDomain_6cb5854e-3fa4-431d-ae66-0925c3fc284f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_SECSchedule1209AllowancePrepaidExpensesAndOtherCurrentAssetsMember_54118a79-d852-49b9-a59d-b6c81374cb40" xlink:href="ebs-20231231.xsd#ebs_SECSchedule1209AllowancePrepaidExpensesAndOtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ValuationAllowancesAndReservesDomain_6cb5854e-3fa4-431d-ae66-0925c3fc284f" xlink:to="loc_ebs_SECSchedule1209AllowancePrepaidExpensesAndOtherCurrentAssetsMember_54118a79-d852-49b9-a59d-b6c81374cb40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_dea57604-16cd-4344-b8cd-2aa2beefa22b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ValuationAndQualifyingAccountsDisclosureLineItems_b7b8d06d-9e1c-4189-af39-732c33632bc8" xlink:to="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_dea57604-16cd-4344-b8cd-2aa2beefa22b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_21ec5e5f-5974-4d63-9f18-6dd774d0ba3f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_dea57604-16cd-4344-b8cd-2aa2beefa22b" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesBalance_21ec5e5f-5974-4d63-9f18-6dd774d0ba3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_c8dea8f2-1ff1-43b8-a940-376b7005da1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_dea57604-16cd-4344-b8cd-2aa2beefa22b" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense_c8dea8f2-1ff1-43b8-a940-376b7005da1f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesDeductions_8bc5dc19-389f-48f4-8b1c-0ea0bda9c4e4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesDeductions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_dea57604-16cd-4344-b8cd-2aa2beefa22b" xlink:to="loc_us-gaap_ValuationAllowancesAndReservesDeductions_8bc5dc19-389f-48f4-8b1c-0ea0bda9c4e4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ValuationAllowancesAndReservesBalance_d6dca8be-c847-41ab-a331-f5211e2ef8ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ValuationAllowancesAndReservesBalance"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="simple" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-roles-2023.xsd#eedm"/>
  <link:definitionLink xlink:role="http://fasb.org/us-gaap/role/eedm/ExtensibleEnumerationLists" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetsAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssetsNoncurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_OtherAssetsNoncurrent" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsAbstract" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementAbstract" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementAbstract" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2023/ecd-2023.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember_865bd445-1c35-487e-8af4-1a0fab728ce0" xlink:href="ebs-20231231.xsd#ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_ebs_PerformanceSharesAndRestrictedStockUnitsRSUsMember_865bd445-1c35-487e-8af4-1a0fab728ce0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PerformanceSharesMember" xlink:type="arc" order="6"/>
  </link:definitionLink>
</link:linkbase>
