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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019cb4d6-86d0-7e6a-9c8d-d254be46240f,g:d6b40f4a-c0e7-4201-8501-b710a704b9b5-->
<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://www.bmrn.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="simple" xlink:href="bmrn-20260331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cb4d6-8814-7be5-a301-080c6425b90b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_StatementTable_019cb4d6-8814-7be5-a301-080c6425b90b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cb4d6-8814-712a-ae9d-79b3455ff30f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cb4d6-8814-7be5-a301-080c6425b90b" xlink:to="loc_srt_ProductOrServiceAxis_019cb4d6-8814-712a-ae9d-79b3455ff30f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-712a-ae9d-79b3455ff30f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-712a-ae9d-79b3455ff30f" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-712a-ae9d-79b3455ff30f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7f8e-ac85-9a8d6825ccb4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-712a-ae9d-79b3455ff30f" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7f8e-ac85-9a8d6825ccb4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019cb4d6-8814-7a47-a7a6-0bcc25547235" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7f8e-ac85-9a8d6825ccb4" xlink:to="loc_us-gaap_ProductMember_019cb4d6-8814-7a47-a7a6-0bcc25547235" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_RoyaltyAndOtherMember_019cb4d6-8814-719d-97b9-67b1434b61d2" xlink:href="bmrn-20260331.xsd#bmrn_RoyaltyAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7f8e-ac85-9a8d6825ccb4" xlink:to="loc_bmrn_RoyaltyAndOtherMember_019cb4d6-8814-719d-97b9-67b1434b61d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019cb4d6-8814-766a-8495-ccce63d67d45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_RevenuesAbstract_019cb4d6-8814-766a-8495-ccce63d67d45" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7a31-ab23-8a1c740c10e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019cb4d6-8814-766a-8495-ccce63d67d45" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7a31-ab23-8a1c740c10e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_019cb4d6-8814-7782-8414-4a350fb615fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:to="loc_us-gaap_CostOfRevenue_019cb4d6-8814-7782-8414-4a350fb615fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019cb4d6-8814-731a-a4e8-18d5e5792548" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019cb4d6-8814-731a-a4e8-18d5e5792548" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cb4d6-8814-773e-81de-d3c723b46f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019cb4d6-8814-773e-81de-d3c723b46f2b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019cb4d6-8814-700e-abdc-4b252ebcc46a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019cb4d6-8814-700e-abdc-4b252ebcc46a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019cb4d6-8814-706d-91a1-f15044e7baba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CostsAndExpensesAbstract_019cb4d6-8814-738f-a1aa-5bceb8e11311" xlink:to="loc_us-gaap_CostsAndExpenses_019cb4d6-8814-706d-91a1-f15044e7baba" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019cb4d6-8814-749a-bb21-118e4687ca49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_OperatingIncomeLoss_019cb4d6-8814-749a-bb21-118e4687ca49" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019cb4d6-8814-77b1-b11c-c332afbd3f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019cb4d6-8814-77b1-b11c-c332afbd3f7f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019cb4d6-8814-7f41-af2a-28017d681dbb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019cb4d6-8814-7f41-af2a-28017d681dbb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_019cb4d6-8814-756a-8138-60fcfa8ee316" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_019cb4d6-8814-756a-8138-60fcfa8ee316" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cb4d6-8814-75d2-a6c2-2d44f9bd8731" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019cb4d6-8814-75d2-a6c2-2d44f9bd8731" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019cb4d6-8814-7adc-9a26-9609db074e65" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019cb4d6-8814-7adc-9a26-9609db074e65" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-741a-8604-1abbf7534e00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-741a-8604-1abbf7534e00" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019cb4d6-8814-7e26-bda9-98964727506f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_EarningsPerShareBasic_019cb4d6-8814-7e26-bda9-98964727506f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019cb4d6-8814-7bbd-be53-05a5bad1b3f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019cb4d6-8814-7bbd-be53-05a5bad1b3f0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cb4d6-8814-7b54-8e4c-d0a619817d87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cb4d6-8814-7b54-8e4c-d0a619817d87" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cb4d6-8814-742f-8aac-aa298d662966" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cb4d6-8814-742f-8aac-aa298d662966" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019cb4d6-8814-7e9d-8d95-da3c71fc52dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7964-a9ba-39c38c8f1a26" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_019cb4d6-8814-7e9d-8d95-da3c71fc52dd" xlink:type="arc" order="13"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="bmrn-20260331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cb4d6-8814-7174-ba94-b862f70f34a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cb4d6-8814-7dea-8249-445fba85a8f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7174-ba94-b862f70f34a3" xlink:to="loc_us-gaap_StatementTable_019cb4d6-8814-7dea-8249-445fba85a8f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-75ac-90a2-623e36f14af7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cb4d6-8814-7dea-8249-445fba85a8f6" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-75ac-90a2-623e36f14af7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-75ac-90a2-623e36f14af7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-75ac-90a2-623e36f14af7" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-75ac-90a2-623e36f14af7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-75ac-90a2-623e36f14af7" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019cb4d6-8814-78c4-9986-2c4e17f11e2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:to="loc_us-gaap_CommonStockMember_019cb4d6-8814-78c4-9986-2c4e17f11e2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019cb4d6-8814-7a80-a99b-094883c040c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019cb4d6-8814-7a80-a99b-094883c040c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019cb4d6-8814-7fc2-980f-dff0dcbaed4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationShareBasedPaymentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:to="loc_us-gaap_DeferredCompensationShareBasedPaymentsMember_019cb4d6-8814-7fc2-980f-dff0dcbaed4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-730f-b508-6d2286137c79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-730f-b508-6d2286137c79" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019cb4d6-8814-73dd-9e3e-18dcdb3e9d09" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7576-b34a-b842b7facca3" xlink:to="loc_us-gaap_RetainedEarningsMember_019cb4d6-8814-73dd-9e3e-18dcdb3e9d09" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cb4d6-8814-7174-ba94-b862f70f34a3" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019cb4d6-8814-7551-a6da-b2ae4567bd0e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019cb4d6-8814-7551-a6da-b2ae4567bd0e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_StockIssuedDuringPeriodSharesNewIssuesNetExcessTaxBenefitTaxDeficiency_019cb4d6-8814-7727-a45d-ce8e1c882dc9" xlink:href="bmrn-20260331.xsd#bmrn_StockIssuedDuringPeriodSharesNewIssuesNetExcessTaxBenefitTaxDeficiency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_bmrn_StockIssuedDuringPeriodSharesNewIssuesNetExcessTaxBenefitTaxDeficiency_019cb4d6-8814-7727-a45d-ce8e1c882dc9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019cb4d6-8814-7a26-8167-77b0a9883be4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cb4d6-8814-7e28-92fb-fab14d8f1707" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_us-gaap_StockholdersEquity_019cb4d6-8814-7e28-92fb-fab14d8f1707" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_StockIssuedDuringPeriodValueNewIssuesNetExcessTaxBenefitTaxDeficiency_019cb4d6-8814-71bf-93e2-2b1c68861184" xlink:href="bmrn-20260331.xsd#bmrn_StockIssuedDuringPeriodValueNewIssuesNetExcessTaxBenefitTaxDeficiency"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_bmrn_StockIssuedDuringPeriodValueNewIssuesNetExcessTaxBenefitTaxDeficiency_019cb4d6-8814-71bf-93e2-2b1c68861184" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cb4d6-8814-721a-8077-329b3797da25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cb4d6-8814-721a-8077-329b3797da25" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_AdjustmentsToAdditionalPaidInCapitalSharesHeldByNonqualifiedDeferredCompensationPlan_019cb4d6-8814-753a-9c90-4ada8272aa04" xlink:href="bmrn-20260331.xsd#bmrn_AdjustmentsToAdditionalPaidInCapitalSharesHeldByNonqualifiedDeferredCompensationPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_bmrn_AdjustmentsToAdditionalPaidInCapitalSharesHeldByNonqualifiedDeferredCompensationPlan_019cb4d6-8814-753a-9c90-4ada8272aa04" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019cb4d6-8814-740a-824b-8ed04adc312c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019cb4d6-8814-740a-824b-8ed04adc312c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-725a-b2ba-f95bbc91ab81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cb4d6-8814-73eb-8daa-2c3a12a69fc8" xlink:to="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-725a-b2ba-f95bbc91ab81" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cb4d6-8814-77e5-8b16-5b6c49a16823" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/FINANCIALINSTRUMENTSScheduleofCashCashEquivalentsRestrictedCashEquivalentsandAvailableforSaleSecuritiesbySignificantInvestmentCategoryDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#FINANCIALINSTRUMENTSScheduleofCashCashEquivalentsRestrictedCashEquivalentsandAvailableforSaleSecuritiesbySignificantInvestmentCategoryDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/FINANCIALINSTRUMENTSScheduleofCashCashEquivalentsRestrictedCashEquivalentsandAvailableforSaleSecuritiesbySignificantInvestmentCategoryDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:href="bmrn-20260331.xsd#bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:href="bmrn-20260331.xsd#bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7587-bce3-6341a3b019f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7587-bce3-6341a3b019f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7587-bce3-6341a3b019f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7587-bce3-6341a3b019f7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7587-bce3-6341a3b019f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-71e2-bb70-cf5225a6ec70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7587-bce3-6341a3b019f7" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-71e2-bb70-cf5225a6ec70" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019cb4d6-8814-78a8-82a2-7107086b402c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-71e2-bb70-cf5225a6ec70" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019cb4d6-8814-78a8-82a2-7107086b402c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-7f40-bbc8-cb245ade69e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-71e2-bb70-cf5225a6ec70" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-7f40-bbc8-cb245ade69e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_019cb4d6-8814-75fb-bcbc-dbda402b38e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:to="loc_us-gaap_FinancialInstrumentAxis_019cb4d6-8814-75fb-bcbc-dbda402b38e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-75fb-bcbc-dbda402b38e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019cb4d6-8814-75fb-bcbc-dbda402b38e3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-75fb-bcbc-dbda402b38e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_019cb4d6-8814-75fb-bcbc-dbda402b38e3" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019cb4d6-8814-7a5d-bd8f-8448cab5f9d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019cb4d6-8814-7a5d-bd8f-8448cab5f9d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateDebtSecuritiesMember_019cb4d6-8814-7855-ae41-9e20a6fb3fe8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:to="loc_us-gaap_CorporateDebtSecuritiesMember_019cb4d6-8814-7855-ae41-9e20a6fb3fe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019cb4d6-8814-70a4-b46a-5b0c78aa672a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_019cb4d6-8814-70a4-b46a-5b0c78aa672a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetBackedSecuritiesMember_019cb4d6-8814-739d-a47e-ad8c2f4136ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_019cb4d6-8814-7e40-a56e-d459bea8b699" xlink:to="loc_us-gaap_AssetBackedSecuritiesMember_019cb4d6-8814-739d-a47e-ad8c2f4136ce" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cb4d6-8814-7394-9aae-d73b5e451c08" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:to="loc_srt_RangeAxis_019cb4d6-8814-7394-9aae-d73b5e451c08" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cb4d6-8814-7394-9aae-d73b5e451c08_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cb4d6-8814-7394-9aae-d73b5e451c08" xlink:to="loc_srt_RangeMember_019cb4d6-8814-7394-9aae-d73b5e451c08_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cb4d6-8814-78fc-8cdc-8294506e0945" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cb4d6-8814-7394-9aae-d73b5e451c08" xlink:to="loc_srt_RangeMember_019cb4d6-8814-78fc-8cdc-8294506e0945" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cb4d6-8814-7386-93bf-80db7bf98854" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cb4d6-8814-78fc-8cdc-8294506e0945" xlink:to="loc_srt_MaximumMember_019cb4d6-8814-7386-93bf-80db7bf98854" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cb4d6-8814-751d-ae26-e25ff9ce0b41" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cb4d6-8814-78fc-8cdc-8294506e0945" xlink:to="loc_srt_MinimumMember_019cb4d6-8814-751d-ae26-e25ff9ce0b41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_019de563-5811-7be4-8f31-7d289dccaca2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesTable_019cb4d6-8814-7681-a980-9598b27a12f6" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_019de563-5811-7be4-8f31-7d289dccaca2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-7be4-8f31-7d289dccaca2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019de563-5811-7be4-8f31-7d289dccaca2" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-7be4-8f31-7d289dccaca2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019de563-5811-7be4-8f31-7d289dccaca2" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsMember_019de563-811e-73af-930f-f1f9b8a61d91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:to="loc_us-gaap_CashAndCashEquivalentsMember_019de563-811e-73af-930f-f1f9b8a61d91" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_RestrictedCashEquivalentNoncurrentMember_019de563-ee90-7314-85db-f9983188117f" xlink:href="bmrn-20260331.xsd#bmrn_RestrictedCashEquivalentNoncurrentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:to="loc_bmrn_RestrictedCashEquivalentNoncurrentMember_019de563-ee90-7314-85db-f9983188117f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestmentsMember_019de56d-5a09-73af-a1d4-aa8ac37dc960" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:to="loc_us-gaap_ShortTermInvestmentsMember_019de56d-5a09-73af-a1d4-aa8ac37dc960" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_LongTermInvestmentsMember_019de56d-9ec5-7168-a49f-c63f41ca1f69" xlink:href="bmrn-20260331.xsd#bmrn_LongTermInvestmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019de563-5811-74a3-ac3c-fcf55c7b0bb5" xlink:to="loc_bmrn_LongTermInvestmentsMember_019de56d-9ec5-7168-a49f-c63f41ca1f69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Cash_019cb4d6-8814-7a1e-9171-bd98689dc824" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Cash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_Cash_019cb4d6-8814-7a1e-9171-bd98689dc824" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019cb4d6-8814-7e47-b9d9-4b86058bfe0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019cb4d6-8814-7e47-b9d9-4b86058bfe0a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019cb4d6-8814-743d-9716-42c3360bdd90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019cb4d6-8814-743d-9716-42c3360bdd90" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019cb4d6-8814-7e3a-8bf5-c1cff953473e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019cb4d6-8814-7e3a-8bf5-c1cff953473e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019cb4d6-8814-7110-ad64-dc592f1f6e32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019cb4d6-8814-7110-ad64-dc592f1f6e32" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019cb4d6-8814-7cf7-a767-f1409fa07055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019cb4d6-8814-7cf7-a767-f1409fa07055" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ShortTermMarketableSecuritiesMaturityPeriod_019cb4d6-8814-74e5-9987-07ed971992e3" xlink:href="bmrn-20260331.xsd#bmrn_ShortTermMarketableSecuritiesMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_bmrn_ShortTermMarketableSecuritiesMaturityPeriod_019cb4d6-8814-74e5-9987-07ed971992e3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_LongTermMarketableSecuritiesMaturityPeriod_019cb4d6-8814-7675-a38d-bf6c9e559843" xlink:href="bmrn-20260331.xsd#bmrn_LongTermMarketableSecuritiesMaturityPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ScheduleOfCashCashEquivalentsAndAvailableForSaleSecuritiesLineItems_019cb4d6-8814-786c-a33f-4b34dd25911c" xlink:to="loc_bmrn_LongTermMarketableSecuritiesMaturityPeriod_019cb4d6-8814-7675-a38d-bf6c9e559843" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#FAIRVALUEMEASUREMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/FAIRVALUEMEASUREMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cb4d6-8814-71ac-a5c1-7762f22265e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cb4d6-8814-71ac-a5c1-7762f22265e0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019cb4d6-8814-71ac-a5c1-7762f22265e0" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-75b7-8642-9ba15959dcfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7e69-8dc5-ab99ae3a2e33" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-75b7-8642-9ba15959dcfe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019cb4d6-8814-7db8-95c2-ec83de195dcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-75b7-8642-9ba15959dcfe" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019cb4d6-8814-7db8-95c2-ec83de195dcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019cb4d6-8814-71ef-a482-35ba6a7744bc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-75b7-8642-9ba15959dcfe" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019cb4d6-8814-71ef-a482-35ba6a7744bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-77d6-9d58-279b86b96004" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-75b7-8642-9ba15959dcfe" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-77d6-9d58-279b86b96004" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019cb4d6-8814-76e6-a148-948feed6fe26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue_019cb4d6-8814-76e6-a148-948feed6fe26" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_019cb4d6-8814-702a-90ed-ef53feb6e891" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:to="loc_us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue_019cb4d6-8814-702a-90ed-ef53feb6e891" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosureAbstract_019cb4d6-8814-78d3-9a2b-1cc07aca910c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:to="loc_us-gaap_AssetsFairValueDisclosureAbstract_019cb4d6-8814-78d3-9a2b-1cc07aca910c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_DeferredCompensationPlanAssetsCurrent_019d92be-f7d3-771c-ba58-f64cdde8af47" xlink:href="bmrn-20260331.xsd#bmrn_DeferredCompensationPlanAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019cb4d6-8814-78d3-9a2b-1cc07aca910c" xlink:to="loc_bmrn_DeferredCompensationPlanAssetsCurrent_019d92be-f7d3-771c-ba58-f64cdde8af47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_019d92be-f7d3-7967-9295-b65ba773459b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019cb4d6-8814-78d3-9a2b-1cc07aca910c" xlink:to="loc_us-gaap_DeferredCompensationPlanAssets_019d92be-f7d3-7967-9295-b65ba773459b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019cb4d6-8814-7710-b794-9e53447fede8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AssetsFairValueDisclosureAbstract_019cb4d6-8814-78d3-9a2b-1cc07aca910c" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019cb4d6-8814-7710-b794-9e53447fede8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019cb4d6-8814-7352-ad3d-849732fb829b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosureAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019cb4d6-8814-79ea-afd3-796246692b3e" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019cb4d6-8814-7352-ad3d-849732fb829b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityCurrent_019d92bf-1d2d-7356-bf8d-2a90d25815d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationLiabilityCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019cb4d6-8814-7352-ad3d-849732fb829b" xlink:to="loc_us-gaap_DeferredCompensationLiabilityCurrent_019d92bf-1d2d-7356-bf8d-2a90d25815d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_019d92bf-1d2d-743e-8277-1ba1c4378c8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019cb4d6-8814-7352-ad3d-849732fb829b" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_019d92bf-1d2d-743e-8277-1ba1c4378c8a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019cb4d6-8814-743f-b62b-a15a75aefb0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosureAbstract_019cb4d6-8814-7352-ad3d-849732fb829b" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_019cb4d6-8814-743f-b62b-a15a75aefb0a" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESNarrativeDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c42-b0e1-35916138b38b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019cb4d6-8814-77a7-8494-06dc7e3e3d37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c42-b0e1-35916138b38b" xlink:to="loc_us-gaap_DerivativeTable_019cb4d6-8814-77a7-8494-06dc7e3e3d37" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-78b2-a8c1-7e16f6ec5341" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-77a7-8494-06dc7e3e3d37" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-78b2-a8c1-7e16f6ec5341" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78b2-a8c1-7e16f6ec5341_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-78b2-a8c1-7e16f6ec5341" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78b2-a8c1-7e16f6ec5341_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-747b-960f-67d83b2f8a93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-78b2-a8c1-7e16f6ec5341" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-747b-960f-67d83b2f8a93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-7ee5-a875-bfa026ad957e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-747b-960f-67d83b2f8a93" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-7ee5-a875-bfa026ad957e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cb4d6-8814-79de-802e-af74e6b53861" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-747b-960f-67d83b2f8a93" xlink:to="loc_us-gaap_NondesignatedMember_019cb4d6-8814-79de-802e-af74e6b53861" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeRemainingMaturity1_019cb4d6-8814-746c-ae15-e80bc8ee61d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeRemainingMaturity1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c42-b0e1-35916138b38b" xlink:to="loc_us-gaap_DerivativeRemainingMaturity1_019cb4d6-8814-746c-ae15-e80bc8ee61d8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_019cb4d6-8814-7d55-b0d4-96bb7ed7a736" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c42-b0e1-35916138b38b" xlink:to="loc_us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths_019cb4d6-8814-7d55-b0d4-96bb7ed7a736" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofAggregateNotionalAmountsfortheDerivativesOutstandingDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofAggregateNotionalAmountsfortheDerivativesOutstandingDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofAggregateNotionalAmountsfortheDerivativesOutstandingDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c6b-82bf-490ca73b450c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019cb4d6-8814-75c4-924a-491aedaf80bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c6b-82bf-490ca73b450c" xlink:to="loc_us-gaap_DerivativeTable_019cb4d6-8814-75c4-924a-491aedaf80bd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-77b3-8ead-bb62e6b668be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-75c4-924a-491aedaf80bd" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-77b3-8ead-bb62e6b668be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-77b3-8ead-bb62e6b668be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-77b3-8ead-bb62e6b668be" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-77b3-8ead-bb62e6b668be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7648-8ec0-d0a92611474d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-77b3-8ead-bb62e6b668be" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7648-8ec0-d0a92611474d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-76d6-8adc-ca72f386295c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7648-8ec0-d0a92611474d" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-76d6-8adc-ca72f386295c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cb4d6-8814-7a72-83a5-9caddc40a369" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7648-8ec0-d0a92611474d" xlink:to="loc_us-gaap_NondesignatedMember_019cb4d6-8814-7a72-83a5-9caddc40a369" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cb4d6-8814-7a73-948a-3074af94f860" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-75c4-924a-491aedaf80bd" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cb4d6-8814-7a73-948a-3074af94f860" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cb4d6-8814-7a73-948a-3074af94f860_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cb4d6-8814-7a73-948a-3074af94f860" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cb4d6-8814-7a73-948a-3074af94f860_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cb4d6-8814-76cf-abe5-3014cf995f81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cb4d6-8814-7a73-948a-3074af94f860" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cb4d6-8814-76cf-abe5-3014cf995f81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019cb4d6-8814-76ed-9eac-83fc9c498904" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cb4d6-8814-76cf-abe5-3014cf995f81" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019cb4d6-8814-76ed-9eac-83fc9c498904" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionAxis_019cb4d6-8814-7541-affc-e294182cbb07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-75c4-924a-491aedaf80bd" xlink:to="loc_us-gaap_PositionAxis_019cb4d6-8814-7541-affc-e294182cbb07" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019cb4d6-8814-7541-affc-e294182cbb07_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PositionAxis_019cb4d6-8814-7541-affc-e294182cbb07" xlink:to="loc_us-gaap_PositionDomain_019cb4d6-8814-7541-affc-e294182cbb07_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PositionDomain_019cb4d6-8814-7277-bdc0-1f4dc32728c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PositionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PositionAxis_019cb4d6-8814-7541-affc-e294182cbb07" xlink:to="loc_us-gaap_PositionDomain_019cb4d6-8814-7277-bdc0-1f4dc32728c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortMember_019cb4d6-8814-7973-a86b-863eb4a8b8ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019cb4d6-8814-7277-bdc0-1f4dc32728c7" xlink:to="loc_us-gaap_ShortMember_019cb4d6-8814-7973-a86b-863eb4a8b8ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongMember_019cb4d6-8814-77d4-81e5-93b847e0cf24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PositionDomain_019cb4d6-8814-7277-bdc0-1f4dc32728c7" xlink:to="loc_us-gaap_LongMember_019cb4d6-8814-77d4-81e5-93b847e0cf24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019cb4d6-8814-78da-91cb-e67d7cb661bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7c6b-82bf-490ca73b450c" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019cb4d6-8814-78da-91cb-e67d7cb661bd" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofFairValueCarryingAmountsofDerivativesDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofFairValueCarryingAmountsofDerivativesDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofFairValueCarryingAmountsofDerivativesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7579-bded-ee144c202f9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019cb4d6-8814-7d24-8a7d-8c21b700c5c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7579-bded-ee144c202f9d" xlink:to="loc_us-gaap_DerivativeTable_019cb4d6-8814-7d24-8a7d-8c21b700c5c6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7096-bfb3-324a95d00c26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-7d24-8a7d-8c21b700c5c6" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7096-bfb3-324a95d00c26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7096-bfb3-324a95d00c26_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7096-bfb3-324a95d00c26" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7096-bfb3-324a95d00c26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7cc9-b2f3-cb0cca9232be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019cb4d6-8814-7096-bfb3-324a95d00c26" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7cc9-b2f3-cb0cca9232be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-7276-b89d-8e35ff02540f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019cb4d6-8814-7cc9-b2f3-cb0cca9232be" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019cb4d6-8814-7276-b89d-8e35ff02540f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-76ba-8253-51b9bfad97fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-7d24-8a7d-8c21b700c5c6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-76ba-8253-51b9bfad97fe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-76ba-8253-51b9bfad97fe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-76ba-8253-51b9bfad97fe" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-76ba-8253-51b9bfad97fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7619-8bb4-208ee9d17385" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-76ba-8253-51b9bfad97fe" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7619-8bb4-208ee9d17385" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-71de-93e0-3593d37ed7ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7619-8bb4-208ee9d17385" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-71de-93e0-3593d37ed7ea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cb4d6-8814-705c-ae2b-2ca9af30e294" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7619-8bb4-208ee9d17385" xlink:to="loc_us-gaap_NondesignatedMember_019cb4d6-8814-705c-ae2b-2ca9af30e294" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_019cb4d6-8814-7e46-8b04-1f21eed3a833" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019cb4d6-8814-7d24-8a7d-8c21b700c5c6" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_019cb4d6-8814-7e46-8b04-1f21eed3a833" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e46-8b04-1f21eed3a833_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019cb4d6-8814-7e46-8b04-1f21eed3a833" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e46-8b04-1f21eed3a833_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BalanceSheetLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_019cb4d6-8814-7e46-8b04-1f21eed3a833" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_019cb4d6-8814-7b6f-b628-861caad71492" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_019cb4d6-8814-7b6f-b628-861caad71492" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_019cb4d6-8814-7563-84e2-38ac18debf97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNoncurrentAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_019cb4d6-8814-7563-84e2-38ac18debf97" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesMember_019cb4d6-8814-70e9-9eca-1e8f42555f47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesMember_019cb4d6-8814-70e9-9eca-1e8f42555f47" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_019cb4d6-8814-7dba-b87e-571546b76614" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNoncurrentLiabilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_019cb4d6-8814-7e54-b372-ce6f9f29b8be" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_019cb4d6-8814-7dba-b87e-571546b76614" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019cb4d6-8814-77b6-a1eb-07e4d0309241" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeAsset"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7579-bded-ee144c202f9d" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeAsset_019cb4d6-8814-77b6-a1eb-07e4d0309241" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019cb4d6-8814-71c7-b03a-804e250d879b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeFairValueOfDerivativeLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019cb4d6-8814-7579-bded-ee144c202f9d" xlink:to="loc_us-gaap_DerivativeFairValueOfDerivativeLiability_019cb4d6-8814-71c7-b03a-804e250d879b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofImpactofGainsandLossesfromDerivativesDesignatedandNotDesignatedasHedgingInstrumentsDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofImpactofGainsandLossesfromDerivativesDesignatedandNotDesignatedasHedgingInstrumentsDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DERIVATIVEINSTRUMENTSANDHEDGINGSTRATEGIESScheduleofImpactofGainsandLossesfromDerivativesDesignatedandNotDesignatedasHedgingInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cb4d6-8814-714b-8591-1ac4dec8a2e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cb4d6-8814-714b-8591-1ac4dec8a2e8" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-7b25-8e7c-5adb819c85fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-7b25-8e7c-5adb819c85fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7b25-8e7c-5adb819c85fb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-7b25-8e7c-5adb819c85fb" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-7b25-8e7c-5adb819c85fb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78a6-a733-6cf927a30c63" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cb4d6-8814-7b25-8e7c-5adb819c85fb" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78a6-a733-6cf927a30c63" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-73f9-91ef-9783a27236ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78a6-a733-6cf927a30c63" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cb4d6-8814-73f9-91ef-9783a27236ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NondesignatedMember_019cb4d6-8814-751d-9f7a-932f3d8b5f83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NondesignatedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cb4d6-8814-78a6-a733-6cf927a30c63" xlink:to="loc_us-gaap_NondesignatedMember_019cb4d6-8814-751d-9f7a-932f3d8b5f83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7b9b-874c-e6603c0b46ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7b9b-874c-e6603c0b46ea" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7b9b-874c-e6603c0b46ea_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7b9b-874c-e6603c0b46ea" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7b9b-874c-e6603c0b46ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-772c-a814-d7b7bafba24b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7b9b-874c-e6603c0b46ea" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-772c-a814-d7b7bafba24b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019cb4d6-8814-71e0-aa7d-748daf5a035f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-772c-a814-d7b7bafba24b" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019cb4d6-8814-71e0-aa7d-748daf5a035f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7585-a3a0-8928dfc10957" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:to="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7585-a3a0-8928dfc10957" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7585-a3a0-8928dfc10957_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7585-a3a0-8928dfc10957" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7585-a3a0-8928dfc10957_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-704f-97df-613148c6caa7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7585-a3a0-8928dfc10957" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-704f-97df-613148c6caa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019cb4d6-8814-7bc8-8d6d-1b0860dba8f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-704f-97df-613148c6caa7" xlink:to="loc_us-gaap_ProductMember_019cb4d6-8814-7bc8-8d6d-1b0860dba8f1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7eef-8038-118941a985b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipByIncomeStatementLocationByDerivativeInstrumentRiskTable_019cb4d6-8814-7a78-bd9c-c9c00a79e0ed" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7eef-8038-118941a985b6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-7eef-8038-118941a985b6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7eef-8038-118941a985b6" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-7eef-8038-118941a985b6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-70a9-8759-2ef262f10403" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7eef-8038-118941a985b6" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-70a9-8759-2ef262f10403" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpenseMember_019cb4d6-8814-7e4d-854f-440642922d03" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-70a9-8759-2ef262f10403" xlink:to="loc_us-gaap_OperatingExpenseMember_019cb4d6-8814-7e4d-854f-440642922d03" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019cb4d6-8814-7beb-89bd-e35b8ed1b949" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cb4d6-8814-714b-8591-1ac4dec8a2e8" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019cb4d6-8814-7beb-89bd-e35b8ed1b949" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019cb4d6-8814-7607-acb7-95c55084027a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossLineItems_019cb4d6-8814-714b-8591-1ac4dec8a2e8" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019cb4d6-8814-7607-acb7-95c55084027a" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DEBTNarrativeDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DEBTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DEBTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019dadd4-0d1c-7429-b592-3c9d621bf512" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:to="loc_us-gaap_DebtInstrumentAxis_019dadd4-0d1c-7429-b592-3c9d621bf512" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7429-b592-3c9d621bf512_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019dadd4-0d1c-7429-b592-3c9d621bf512" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7429-b592-3c9d621bf512_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7ebc-a1cf-62a72825d5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019dadd4-0d1c-7429-b592-3c9d621bf512" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7ebc-a1cf-62a72825d5a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember_019dadd4-0d1c-79b0-9465-317be28e62ca" xlink:href="bmrn-20260331.xsd#bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7ebc-a1cf-62a72825d5a3" xlink:to="loc_bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember_019dadd4-0d1c-79b0-9465-317be28e62ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_A364DaySeniorSecuredBridgeFacilityMember_019dbe0c-0b64-729e-8a79-907805828210" xlink:href="bmrn-20260331.xsd#bmrn_A364DaySeniorSecuredBridgeFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019dadd4-0d1c-7ebc-a1cf-62a72825d5a3" xlink:to="loc_bmrn_A364DaySeniorSecuredBridgeFacilityMember_019dbe0c-0b64-729e-8a79-907805828210" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019dadd4-0d1c-7ad6-b454-ad54abbd9095" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019dadd4-0d1c-7ad6-b454-ad54abbd9095" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019dadd4-0d1c-7ad6-b454-ad54abbd9095_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019dadd4-0d1c-7ad6-b454-ad54abbd9095" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019dadd4-0d1c-7ad6-b454-ad54abbd9095_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019dadd4-0d1c-79e8-8279-3fb686188cc8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019dadd4-0d1c-7ad6-b454-ad54abbd9095" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019dadd4-0d1c-79e8-8279-3fb686188cc8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019dc02a-9fc5-7e41-b79b-8b429f391e25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019dadd4-0d1c-79e8-8279-3fb686188cc8" xlink:to="loc_us-gaap_SeniorNotesMember_019dc02a-9fc5-7e41-b79b-8b429f391e25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019dbe0c-0b64-7bc1-83fa-5bd078675cd2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019dbe0c-0b64-7bc1-83fa-5bd078675cd2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019dbe0c-0b64-7bc1-83fa-5bd078675cd2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019dbe0c-0b64-7bc1-83fa-5bd078675cd2" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019dbe0c-0b64-7bc1-83fa-5bd078675cd2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019dbe0c-0b64-7c6e-828b-b4f770f9ecef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019dbe0c-0b64-7bc1-83fa-5bd078675cd2" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019dbe0c-0b64-7c6e-828b-b4f770f9ecef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BridgeLoanMember_019dbe0c-0b64-74ef-b70e-6ceb54d13ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BridgeLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019dbe0c-0b64-7c6e-828b-b4f770f9ecef" xlink:to="loc_us-gaap_BridgeLoanMember_019dbe0c-0b64-74ef-b70e-6ceb54d13ab5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019dadd4-0d1c-7299-b1bf-4a67c3a0cf72" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de556-a6d0-77f2-bc87-d52d4b54179e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019de556-a6d0-7daf-bcc5-7dcfdeebf4b5" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de556-a6d0-77f2-bc87-d52d4b54179e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_AmicusTherapeuticsMember_019de556-c1fa-760c-898b-e996a993e186" xlink:href="bmrn-20260331.xsd#bmrn_AmicusTherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de556-a6d0-77f2-bc87-d52d4b54179e" xlink:to="loc_bmrn_AmicusTherapeuticsMember_019de556-c1fa-760c-898b-e996a993e186" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019dadd4-0d1c-756e-82ed-8aba8624b85a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019dadd4-0d1c-756e-82ed-8aba8624b85a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019dbe0c-0b64-796e-8ad3-40f3b01b0727" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019dbe0c-0b64-796e-8ad3-40f3b01b0727" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019dadd4-0d1c-7fd1-b0ad-ae478d3436eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019dadd4-0d1c-7fd1-b0ad-ae478d3436eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromDebtNetOfIssuanceCosts_019dadd4-0d1c-7f41-9643-39e2e81e6c2c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromDebtNetOfIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_ProceedsFromDebtNetOfIssuanceCosts_019dadd4-0d1c-7f41-9643-39e2e81e6c2c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFinanceCostsGross_019dc028-6564-760a-9ed0-6efe48b3f0de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFinanceCostsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DeferredFinanceCostsGross_019dc028-6564-760a-9ed0-6efe48b3f0de" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019dbe0d-44c9-75ba-bbc9-240f51ecc37e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtRelatedCommitmentFeesAndDebtIssuanceCosts_019dbe0d-44c9-75ba-bbc9-240f51ecc37e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount_019dbe10-cfa8-7f23-aa14-a255e28c60be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019dadd4-0d1c-7dbd-9157-cb0aeb2ff060" xlink:to="loc_us-gaap_DebtInstrumentFeeAmount_019dbe10-cfa8-7f23-aa14-a255e28c60be" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/DEBTScheduleofLongTermDebtDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#DEBTScheduleofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/DEBTScheduleofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019cb4d6-8814-709d-bc4d-78b177f2d6cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_DebtInstrumentTable_019cb4d6-8814-709d-bc4d-78b177f2d6cb" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019cb4d6-8814-7e39-b578-3907c1a53bdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cb4d6-8814-709d-bc4d-78b177f2d6cb" xlink:to="loc_us-gaap_DebtInstrumentAxis_019cb4d6-8814-7e39-b578-3907c1a53bdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-7e39-b578-3907c1a53bdf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cb4d6-8814-7e39-b578-3907c1a53bdf" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-7e39-b578-3907c1a53bdf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-70b6-b16f-d6c4af7c91e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019cb4d6-8814-7e39-b578-3907c1a53bdf" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-70b6-b16f-d6c4af7c91e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember_019d851b-de67-7e40-a3cb-c52dfa4c5b39" xlink:href="bmrn-20260331.xsd#bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-70b6-b16f-d6c4af7c91e8" xlink:to="loc_bmrn_FivePointFivePercentSeniorUnsecuredNotesDueInFebruaryTwoThousandThirtyFourMember_019d851b-de67-7e40-a3cb-c52dfa4c5b39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_OnePointTwoFivePercentSeniorSubordinatedConvertibleNotesDueInMay2027Member_019cb4d6-8814-7378-953e-4ca6911a10e6" xlink:href="bmrn-20260331.xsd#bmrn_OnePointTwoFivePercentSeniorSubordinatedConvertibleNotesDueInMay2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019cb4d6-8814-70b6-b16f-d6c4af7c91e8" xlink:to="loc_bmrn_OnePointTwoFivePercentSeniorSubordinatedConvertibleNotesDueInMay2027Member_019cb4d6-8814-7378-953e-4ca6911a10e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019cb4d6-8814-709d-bc4d-78b177f2d6cb" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-72ff-af73-906487fcf39c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019dc02a-17b0-7aa4-8f78-d22bf9cd2e9e" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-72ff-af73-906487fcf39c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019dc02a-3978-78b1-8e85-ec4c5ddd2d0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-72ff-af73-906487fcf39c" xlink:to="loc_us-gaap_SeniorNotesMember_019dc02a-3978-78b1-8e85-ec4c5ddd2d0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorSubordinatedNotesMember_019dc02a-5a41-7dfa-a74e-d5db672d0fee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorSubordinatedNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019dc02a-17b0-72ff-af73-906487fcf39c" xlink:to="loc_us-gaap_SeniorSubordinatedNotesMember_019dc02a-5a41-7dfa-a74e-d5db672d0fee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019cb4d6-8814-7e4e-b07b-300421a2370d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019cb4d6-8814-7e4e-b07b-300421a2370d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019cb4d6-8814-7ad9-8f86-4bc57e7a9e18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019cb4d6-8814-7ad9-8f86-4bc57e7a9e18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019cb4d6-8814-70ce-9195-21174d5f1ce2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019cb4d6-8814-70ce-9195-21174d5f1ce2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019cb4d6-8814-70f4-af22-1c7e8b62bb7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_LongTermDebt_019cb4d6-8814-70f4-af22-1c7e8b62bb7d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019cb4d6-8814-7517-ac57-041549a8a980" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019cb4d6-8814-7857-9210-d105a65127c4" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019cb4d6-8814-7517-ac57-041549a8a980" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#ACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMEDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cb4d6-8814-7e71-a7e3-282a9c210630" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cb4d6-8814-74e6-9296-504b468e97dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cb4d6-8814-7e71-a7e3-282a9c210630" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cb4d6-8814-74e6-9296-504b468e97dd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7fbc-ab1b-19295398010d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019cb4d6-8814-74e6-9296-504b468e97dd" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7fbc-ab1b-19295398010d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7fbc-ab1b-19295398010d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7fbc-ab1b-19295398010d" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-7fbc-ab1b-19295398010d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-76e3-965b-92b07f496e45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cb4d6-8814-7fbc-ab1b-19295398010d" xlink:to="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-76e3-965b-92b07f496e45" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-71b0-993d-f865db9928ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cb4d6-8814-76e3-965b-92b07f496e45" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-71b0-993d-f865db9928ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019cb4d6-8814-76ee-81bb-1197c42419e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-71b0-993d-f865db9928ee" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019cb4d6-8814-76ee-81bb-1197c42419e6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019cb4d6-8814-785c-b4a1-7fa5d8d9c4f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019cb4d6-8814-71b0-993d-f865db9928ee" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_019cb4d6-8814-785c-b4a1-7fa5d8d9c4f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019cb4d6-8814-7e71-a7e3-282a9c210630" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cb4d6-8814-702a-b45d-427e13b93f89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:to="loc_us-gaap_StockholdersEquity_019cb4d6-8814-702a-b45d-427e13b93f89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_019cb4d6-8814-7fe6-9c49-41b02e7f4169" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:to="loc_us-gaap_OciBeforeReclassificationsBeforeTaxAttributableToParent_019cb4d6-8814-7fe6-9c49-41b02e7f4169" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019cb4d6-8814-7f77-a7e5-eb6b3a2d2273" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodBeforeTaxAttributableToParent_019cb4d6-8814-7f77-a7e5-eb6b3a2d2273" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019cb4d6-8814-736a-9749-6eac56400787" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019cb4d6-8814-736a-9749-6eac56400787" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019cb4d6-8814-76d1-9cf1-df663148d2de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019cb4d6-8814-7fce-9ddd-753f5170439f" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019cb4d6-8814-76d1-9cf1-df663148d2de" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cb4d6-8814-7c1b-931c-12ad7eb7d85a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SEGMENTINFORMATIONNarrativeDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SEGMENTINFORMATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SEGMENTINFORMATIONNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:href="bmrn-20260331.xsd#bmrn_ConcentrationRiskAndGeographicInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ConcentrationRiskAndGeographicInformationTable_019cb4d6-8814-777e-9f6a-4f0b71f86d6c" xlink:href="bmrn-20260331.xsd#bmrn_ConcentrationRiskAndGeographicInformationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:to="loc_bmrn_ConcentrationRiskAndGeographicInformationTable_019cb4d6-8814-777e-9f6a-4f0b71f86d6c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationTable_019cb4d6-8814-777e-9f6a-4f0b71f86d6c" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7d23-9f8b-d1d3dfbf79a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-72bf-9e2e-ab68c7e5b7f7" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7d23-9f8b-d1d3dfbf79a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditConcentrationRiskMember_019cb4d6-8814-7b44-8fd0-b1bce5329991" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7d23-9f8b-d1d3dfbf79a4" xlink:to="loc_us-gaap_CreditConcentrationRiskMember_019cb4d6-8814-7b44-8fd0-b1bce5329991" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-70a3-aa44-8758f61cfcfa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationTable_019cb4d6-8814-777e-9f6a-4f0b71f86d6c" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-70a3-aa44-8758f61cfcfa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-70a3-aa44-8758f61cfcfa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-70a3-aa44-8758f61cfcfa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-70a3-aa44-8758f61cfcfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-7cf0-ac72-3985c3fb7a8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-70a3-aa44-8758f61cfcfa" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-7cf0-ac72-3985c3fb7a8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableMember_019cb4d6-8814-7696-9552-142074bbaa3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-7cf0-ac72-3985c3fb7a8b" xlink:to="loc_us-gaap_AccountsReceivableMember_019cb4d6-8814-7696-9552-142074bbaa3f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019cb4d6-8814-71bd-b8f6-697efa14de7b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationTable_019cb4d6-8814-777e-9f6a-4f0b71f86d6c" xlink:to="loc_srt_MajorCustomersAxis_019cb4d6-8814-71bd-b8f6-697efa14de7b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-71bd-b8f6-697efa14de7b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019cb4d6-8814-71bd-b8f6-697efa14de7b" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-71bd-b8f6-697efa14de7b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7930-bd3d-423b590a1d57" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019cb4d6-8814-71bd-b8f6-697efa14de7b" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7930-bd3d-423b590a1d57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerOneMember_019cb4d6-8814-77e5-9c9a-443fe0c96da9" xlink:href="bmrn-20260331.xsd#bmrn_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7930-bd3d-423b590a1d57" xlink:to="loc_bmrn_CustomerOneMember_019cb4d6-8814-77e5-9c9a-443fe0c96da9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerTwoMember_019cb4d6-8814-7ffb-a154-d9ea2af27f00" xlink:href="bmrn-20260331.xsd#bmrn_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7930-bd3d-423b590a1d57" xlink:to="loc_bmrn_CustomerTwoMember_019cb4d6-8814-7ffb-a154-d9ea2af27f00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomersMember_019cb4d6-8814-71d0-855c-cfb3985cd402" xlink:href="bmrn-20260331.xsd#bmrn_CustomersMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7930-bd3d-423b590a1d57" xlink:to="loc_bmrn_CustomersMember_019cb4d6-8814-71d0-855c-cfb3985cd402" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_019cb4d6-8814-7a44-b115-47ef7a1b2811" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:to="loc_us-gaap_NumberOfOperatingSegments_019cb4d6-8814-7a44-b115-47ef7a1b2811" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019ce6de-8b4e-7b1d-acc2-aee3ffd496b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:to="loc_us-gaap_NumberOfReportableSegments_019ce6de-8b4e-7b1d-acc2-aee3ffd496b2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019cb4d6-8814-7aed-97b1-a2e9d68943b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019cb4d6-8814-7aed-97b1-a2e9d68943b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_019cb4d6-8814-7349-a4ac-c0a107a56d87" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsReceivableNetCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_ConcentrationRiskAndGeographicInformationLineItems_019cb4d6-8814-7c33-8455-8d9d74b2437b" xlink:to="loc_us-gaap_AccountsReceivableNetCurrent_019cb4d6-8814-7349-a4ac-c0a107a56d87" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofReportableSegmentInformationDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SEGMENTINFORMATIONScheduleofReportableSegmentInformationDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofReportableSegmentInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-787e-bf3b-ed1c0b0e21f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-787e-bf3b-ed1c0b0e21f4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cb4d6-8814-730f-b3db-f9356e6a46d2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-787e-bf3b-ed1c0b0e21f4" xlink:to="loc_srt_ProductOrServiceAxis_019cb4d6-8814-730f-b3db-f9356e6a46d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-730f-b3db-f9356e6a46d2_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-730f-b3db-f9356e6a46d2" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-730f-b3db-f9356e6a46d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7217-b0bd-0de4568e772d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-730f-b3db-f9356e6a46d2" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7217-b0bd-0de4568e772d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ResearchAndEarlyPipelineMember_019cb4d6-8814-7004-b828-fd01358338c9" xlink:href="bmrn-20260331.xsd#bmrn_ResearchAndEarlyPipelineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7217-b0bd-0de4568e772d" xlink:to="loc_bmrn_ResearchAndEarlyPipelineMember_019cb4d6-8814-7004-b828-fd01358338c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_LaterStageClinicalProgramsMember_019cb4d6-8814-72fd-bf1c-46234b72952b" xlink:href="bmrn-20260331.xsd#bmrn_LaterStageClinicalProgramsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7217-b0bd-0de4568e772d" xlink:to="loc_bmrn_LaterStageClinicalProgramsMember_019cb4d6-8814-72fd-bf1c-46234b72952b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_MarketedProductsMember_019cb4d6-8814-7f90-8d5c-1dbf34649249" xlink:href="bmrn-20260331.xsd#bmrn_MarketedProductsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7217-b0bd-0de4568e772d" xlink:to="loc_bmrn_MarketedProductsMember_019cb4d6-8814-7f90-8d5c-1dbf34649249" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cb4d6-8814-732b-92bf-2dfc8f451529" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-787e-bf3b-ed1c0b0e21f4" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cb4d6-8814-732b-92bf-2dfc8f451529" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cb4d6-8814-732b-92bf-2dfc8f451529_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cb4d6-8814-732b-92bf-2dfc8f451529" xlink:to="loc_us-gaap_SegmentDomain_019cb4d6-8814-732b-92bf-2dfc8f451529_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cb4d6-8814-71e6-860e-1337ba5b0ac6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cb4d6-8814-732b-92bf-2dfc8f451529" xlink:to="loc_us-gaap_SegmentDomain_019cb4d6-8814-71e6-860e-1337ba5b0ac6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ReportableSegmentMember_019cb4d6-8814-7a16-a94c-f5b2f9cd87f4" xlink:href="bmrn-20260331.xsd#bmrn_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cb4d6-8814-71e6-860e-1337ba5b0ac6" xlink:to="loc_bmrn_ReportableSegmentMember_019cb4d6-8814-7a16-a94c-f5b2f9cd87f4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-76d8-b7c8-7965f69afe2e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-76d8-b7c8-7965f69afe2e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfRevenue_019cb4d6-8814-747b-8851-d14d82c55fdc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_CostOfRevenue_019cb4d6-8814-747b-8851-d14d82c55fdc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019cb4d6-8814-7727-8996-d57d587b5aac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019cb4d6-8814-7727-8996-d57d587b5aac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_019cb4d6-8814-7b84-9519-595958f58b83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_SellingAndMarketingExpense_019cb4d6-8814-7b84-9519-595958f58b83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019cb4d6-8814-7b70-837c-35b63a53c2f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019cb4d6-8814-7b70-837c-35b63a53c2f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019cb4d6-8814-7cb2-b1ad-bbff0e8bab29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019cb4d6-8814-7cb2-b1ad-bbff0e8bab29" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-7f10-8ad2-d5cecc74b84c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7323-bef3-107dad28e86e" xlink:to="loc_us-gaap_NetIncomeLoss_019cb4d6-8814-7f10-8ad2-d5cecc74b84c" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofTotalRevenuesandDisaggregatesNetProductRevenuesbyProductDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SEGMENTINFORMATIONScheduleofTotalRevenuesandDisaggregatesNetProductRevenuesbyProductDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofTotalRevenuesandDisaggregatesNetProductRevenuesbyProductDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7fd7-8eac-5b33f53a72eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-7b63-b6aa-c003bffcd647" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7fd7-8eac-5b33f53a72eb" xlink:to="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-7b63-b6aa-c003bffcd647" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7dbb-a636-a1b579838300" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideInformationRevenueFromExternalCustomersByProductsAndServicesTable_019cb4d6-8814-7b63-b6aa-c003bffcd647" xlink:to="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7dbb-a636-a1b579838300" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7dbb-a636-a1b579838300_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7dbb-a636-a1b579838300" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7dbb-a636-a1b579838300_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-77ed-b3ae-685c641101bf" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7dbb-a636-a1b579838300" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-77ed-b3ae-685c641101bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-77ed-b3ae-685c641101bf" xlink:to="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_VOXZOGOMember_019cb4d6-8814-7b7b-b73d-c41d9c0b0444" xlink:href="bmrn-20260331.xsd#bmrn_VOXZOGOMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_VOXZOGOMember_019cb4d6-8814-7b7b-b73d-c41d9c0b0444" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_VIMIZIMMember_019cb4d6-8814-77f9-b541-0f7a662db902" xlink:href="bmrn-20260331.xsd#bmrn_VIMIZIMMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_VIMIZIMMember_019cb4d6-8814-77f9-b541-0f7a662db902" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_NAGLAZYMEMember_019cb4d6-8814-7dd0-a195-d0a3f02de748" xlink:href="bmrn-20260331.xsd#bmrn_NAGLAZYMEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_NAGLAZYMEMember_019cb4d6-8814-7dd0-a195-d0a3f02de748" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_PALYNZIQMember_019cb4d6-8814-7540-8771-3e2dbb133df8" xlink:href="bmrn-20260331.xsd#bmrn_PALYNZIQMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_PALYNZIQMember_019cb4d6-8814-7540-8771-3e2dbb133df8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_BRINEURAMember_019cb4d6-8814-7a49-a815-4db0701cfd3c" xlink:href="bmrn-20260331.xsd#bmrn_BRINEURAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_BRINEURAMember_019cb4d6-8814-7a49-a815-4db0701cfd3c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ALDURAZYMEMember_019cb4d6-8814-744a-8553-a66a4dccb8d0" xlink:href="bmrn-20260331.xsd#bmrn_ALDURAZYMEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_ALDURAZYMEMember_019cb4d6-8814-744a-8553-a66a4dccb8d0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_KUVANMember_019cb4d6-8814-7690-9bc1-7339441ee894" xlink:href="bmrn-20260331.xsd#bmrn_KUVANMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_KUVANMember_019cb4d6-8814-7690-9bc1-7339441ee894" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ROCTAVIANMember_019cb4d6-8814-7a18-bee3-37acf55acb05" xlink:href="bmrn-20260331.xsd#bmrn_ROCTAVIANMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ProductMember_019cb4d6-8814-7e62-afff-803dd2bd0c3e" xlink:to="loc_bmrn_ROCTAVIANMember_019cb4d6-8814-7a18-bee3-37acf55acb05" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_RoyaltyAndOtherMember_019cb4d6-8814-7330-b947-594f846598d8" xlink:href="bmrn-20260331.xsd#bmrn_RoyaltyAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-77ed-b3ae-685c641101bf" xlink:to="loc_bmrn_RoyaltyAndOtherMember_019cb4d6-8814-7330-b947-594f846598d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7e05-a67c-722863af62f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideInformationRevenueFromExternalCustomerLineItems_019cb4d6-8814-7fd7-8eac-5b33f53a72eb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7e05-a67c-722863af62f2" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofDisaggregationofTotalNetProductRevenuesbyGeographicRegionDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SEGMENTINFORMATIONScheduleofDisaggregationofTotalNetProductRevenuesbyGeographicRegionDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofDisaggregationofTotalNetProductRevenuesbyGeographicRegionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019cb4d6-8814-7e24-9f10-34ef9e701c61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019cb4d6-8814-73d4-9017-0b343e0e63ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cb4d6-8814-7e24-9f10-34ef9e701c61" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019cb4d6-8814-73d4-9017-0b343e0e63ad" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019cb4d6-8814-7b72-a4f4-a34c3dfec681" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cb4d6-8814-73d4-9017-0b343e0e63ad" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019cb4d6-8814-7b72-a4f4-a34c3dfec681" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7b72-a4f4-a34c3dfec681_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019cb4d6-8814-7b72-a4f4-a34c3dfec681" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7b72-a4f4-a34c3dfec681_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7aab-87d2-8b84a36dddf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerSalesChannelDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelAxis_019cb4d6-8814-7b72-a4f4-a34c3dfec681" xlink:to="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7aab-87d2-8b84a36dddf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelDirectlyToConsumerMember_019cb4d6-8814-770d-a879-83498e889929" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelDirectlyToConsumerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7aab-87d2-8b84a36dddf6" xlink:to="loc_us-gaap_SalesChannelDirectlyToConsumerMember_019cb4d6-8814-770d-a879-83498e889929" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesChannelThroughIntermediaryMember_019cb4d6-8814-7115-8b70-89b539a6bb37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesChannelThroughIntermediaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerSalesChannelDomain_019cb4d6-8814-7aab-87d2-8b84a36dddf6" xlink:to="loc_us-gaap_SalesChannelThroughIntermediaryMember_019cb4d6-8814-7115-8b70-89b539a6bb37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7473-bd48-98c35c1311a5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cb4d6-8814-73d4-9017-0b343e0e63ad" xlink:to="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7473-bd48-98c35c1311a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7473-bd48-98c35c1311a5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7473-bd48-98c35c1311a5" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7473-bd48-98c35c1311a5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7e73-ae07-e041bb25e163" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cb4d6-8814-7473-bd48-98c35c1311a5" xlink:to="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7e73-ae07-e041bb25e163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ProductsExcludingALDURAZYMEMember_019cb4d6-8814-7060-9e78-8a60e0a0eed5" xlink:href="bmrn-20260331.xsd#bmrn_ProductsExcludingALDURAZYMEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7e73-ae07-e041bb25e163" xlink:to="loc_bmrn_ProductsExcludingALDURAZYMEMember_019cb4d6-8814-7060-9e78-8a60e0a0eed5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_ALDURAZYMEMember_019cb4d6-8814-74a2-bdae-f7c5f8277672" xlink:href="bmrn-20260331.xsd#bmrn_ALDURAZYMEMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7e73-ae07-e041bb25e163" xlink:to="loc_bmrn_ALDURAZYMEMember_019cb4d6-8814-74a2-bdae-f7c5f8277672" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019cb4d6-8814-752a-a3e7-5e52d8ad9efd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cb4d6-8814-7e73-ae07-e041bb25e163" xlink:to="loc_us-gaap_ProductMember_019cb4d6-8814-752a-a3e7-5e52d8ad9efd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019cb4d6-8814-705a-8f78-4b6b4a09555f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cb4d6-8814-73d4-9017-0b343e0e63ad" xlink:to="loc_srt_StatementGeographicalAxis_019cb4d6-8814-705a-8f78-4b6b4a09555f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-705a-8f78-4b6b4a09555f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019cb4d6-8814-705a-8f78-4b6b4a09555f" xlink:to="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-705a-8f78-4b6b4a09555f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019cb4d6-8814-705a-8f78-4b6b4a09555f" xlink:to="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019cb4d6-8814-7341-918d-31ab4b676492" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:to="loc_country_US_019cb4d6-8814-7341-918d-31ab4b676492" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_EuropeMember_019cb4d6-8814-70d0-b36a-9e9130b0b9b9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_EuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:to="loc_srt_EuropeMember_019cb4d6-8814-70d0-b36a-9e9130b0b9b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LatinAmericaMember_019cb4d6-8814-788e-bfba-95d1f20ba11a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LatinAmericaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:to="loc_srt_LatinAmericaMember_019cb4d6-8814-788e-bfba-95d1f20ba11a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_RestOfWorldMember_019cb4d6-8814-7943-b9fc-e3e11ff4deb8" xlink:href="bmrn-20260331.xsd#bmrn_RestOfWorldMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019cb4d6-8814-748e-996b-25f2ed4a5078" xlink:to="loc_bmrn_RestOfWorldMember_019cb4d6-8814-7943-b9fc-e3e11ff4deb8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7be4-8d90-ae916eb8135d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cb4d6-8814-7e24-9f10-34ef9e701c61" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019cb4d6-8814-7be4-8d90-ae916eb8135d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofTotalNetProductRevenuesAttributedtoLargestCustomersDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SEGMENTINFORMATIONScheduleofTotalNetProductRevenuesAttributedtoLargestCustomersDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SEGMENTINFORMATIONScheduleofTotalNetProductRevenuesAttributedtoLargestCustomersDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskLineItems_019cb4d6-8814-77b5-9f06-f56c4bc8c5a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTable_019cb4d6-8814-7f0b-8d0d-96c5aca13cdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019cb4d6-8814-77b5-9f06-f56c4bc8c5a5" xlink:to="loc_us-gaap_ConcentrationRiskTable_019cb4d6-8814-7f0b-8d0d-96c5aca13cdf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-7f62-a1ad-0855a79b6592" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019cb4d6-8814-7f0b-8d0d-96c5aca13cdf" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-7f62-a1ad-0855a79b6592" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7f62-a1ad-0855a79b6592_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-7f62-a1ad-0855a79b6592" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7f62-a1ad-0855a79b6592_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7f14-bebf-6dde474cf90a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cb4d6-8814-7f62-a1ad-0855a79b6592" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7f14-bebf-6dde474cf90a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019cb4d6-8814-75c7-a325-b21664e25597" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019cb4d6-8814-7f14-bebf-6dde474cf90a" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019cb4d6-8814-75c7-a325-b21664e25597" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-721f-abb2-9ec7296d0942" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019cb4d6-8814-7f0b-8d0d-96c5aca13cdf" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-721f-abb2-9ec7296d0942" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-721f-abb2-9ec7296d0942_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-721f-abb2-9ec7296d0942" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-721f-abb2-9ec7296d0942_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-784b-a99f-7f15690faaa9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cb4d6-8814-721f-abb2-9ec7296d0942" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-784b-a99f-7f15690faaa9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_019cb4d6-8814-7dc0-90b5-c64bb8ddb7c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cb4d6-8814-784b-a99f-7f15690faaa9" xlink:to="loc_us-gaap_SalesRevenueNetMember_019cb4d6-8814-7dc0-90b5-c64bb8ddb7c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019cb4d6-8814-755c-994a-9e0589cc2c97" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ConcentrationRiskTable_019cb4d6-8814-7f0b-8d0d-96c5aca13cdf" xlink:to="loc_srt_MajorCustomersAxis_019cb4d6-8814-755c-994a-9e0589cc2c97" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-755c-994a-9e0589cc2c97_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019cb4d6-8814-755c-994a-9e0589cc2c97" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-755c-994a-9e0589cc2c97_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7910-b881-1d79e1381319" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019cb4d6-8814-755c-994a-9e0589cc2c97" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7910-b881-1d79e1381319" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerOneTwoAndThreeMember_019cb4d6-8814-7598-9da6-d29da722045a" xlink:href="bmrn-20260331.xsd#bmrn_CustomerOneTwoAndThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cb4d6-8814-7910-b881-1d79e1381319" xlink:to="loc_bmrn_CustomerOneTwoAndThreeMember_019cb4d6-8814-7598-9da6-d29da722045a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerOneMember_019cb4d6-8814-7ed3-b1c7-6304196285ec" xlink:href="bmrn-20260331.xsd#bmrn_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_CustomerOneTwoAndThreeMember_019cb4d6-8814-7598-9da6-d29da722045a" xlink:to="loc_bmrn_CustomerOneMember_019cb4d6-8814-7ed3-b1c7-6304196285ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerTwoMember_019cb4d6-8814-753a-a1cc-32326e39cc5a" xlink:href="bmrn-20260331.xsd#bmrn_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_CustomerOneTwoAndThreeMember_019cb4d6-8814-7598-9da6-d29da722045a" xlink:to="loc_bmrn_CustomerTwoMember_019cb4d6-8814-753a-a1cc-32326e39cc5a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CustomerThreeMember_019cb4d6-8814-73c0-8d7d-59d3da3316f9" xlink:href="bmrn-20260331.xsd#bmrn_CustomerThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_bmrn_CustomerOneTwoAndThreeMember_019cb4d6-8814-7598-9da6-d29da722045a" xlink:to="loc_bmrn_CustomerThreeMember_019cb4d6-8814-73c0-8d7d-59d3da3316f9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019cb4d6-8814-7687-9710-ec9889585cc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskLineItems_019cb4d6-8814-77b5-9f06-f56c4bc8c5a5" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019cb4d6-8814-7687-9710-ec9889585cc4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/STOCKBASEDCOMPENSATIONDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#STOCKBASEDCOMPENSATIONDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/STOCKBASEDCOMPENSATIONDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cb4d6-8814-7c7b-ad8c-0d030756a999" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cb4d6-8814-7c1b-928e-442ec10e38af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cb4d6-8814-7c7b-ad8c-0d030756a999" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cb4d6-8814-7c1b-928e-442ec10e38af" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7754-b5f3-c5cdb1bfa813" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cb4d6-8814-7c1b-928e-442ec10e38af" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7754-b5f3-c5cdb1bfa813" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-7754-b5f3-c5cdb1bfa813_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7754-b5f3-c5cdb1bfa813" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-7754-b5f3-c5cdb1bfa813_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-78a1-a5f2-7ce05c135c1a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_019cb4d6-8814-7754-b5f3-c5cdb1bfa813" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-78a1-a5f2-7ce05c135c1a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfSalesMember_019cb4d6-8814-752b-9a68-0ff8a8284e95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfSalesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-78a1-a5f2-7ce05c135c1a" xlink:to="loc_us-gaap_CostOfSalesMember_019cb4d6-8814-752b-9a68-0ff8a8284e95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpenseMember_019cb4d6-8814-7ec2-bf42-33a232189785" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-78a1-a5f2-7ce05c135c1a" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpenseMember_019cb4d6-8814-7ec2-bf42-33a232189785" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cb4d6-8814-7ede-9acb-90de4c71389c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_019cb4d6-8814-78a1-a5f2-7ce05c135c1a" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpensesMember_019cb4d6-8814-7ede-9acb-90de4c71389c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cb4d6-8814-790b-83cf-6b9b122993ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cb4d6-8814-7c7b-ad8c-0d030756a999" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cb4d6-8814-790b-83cf-6b9b122993ab" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/RESTRUCTURINGNarrativeDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#RESTRUCTURINGNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/RESTRUCTURINGNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-714c-ba49-8fabdacad396" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7b8d-a7a2-087ed604b743" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-714c-ba49-8fabdacad396" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7b8d-a7a2-087ed604b743" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7a40-847d-37771b45f747" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7b8d-a7a2-087ed604b743" xlink:to="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7a40-847d-37771b45f747" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7a40-847d-37771b45f747_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7a40-847d-37771b45f747" xlink:to="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7a40-847d-37771b45f747_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7cc4-bf18-ec9cade7a9d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7a40-847d-37771b45f747" xlink:to="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7cc4-bf18-ec9cade7a9d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_A2026WorkforceReductionPlanMember_019cb4d6-88bf-7290-ac93-9bae1b1d0e98" xlink:href="bmrn-20260331.xsd#bmrn_A2026WorkforceReductionPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7cc4-bf18-ec9cade7a9d7" xlink:to="loc_bmrn_A2026WorkforceReductionPlanMember_019cb4d6-88bf-7290-ac93-9bae1b1d0e98" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019dbe1b-788d-7bff-a027-4d83e5fdbb6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7b8d-a7a2-087ed604b743" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019dbe1b-788d-7bff-a027-4d83e5fdbb6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019dbe1b-788d-7bff-a027-4d83e5fdbb6c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019dbe1b-788d-7bff-a027-4d83e5fdbb6c" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019dbe1b-788d-7bff-a027-4d83e5fdbb6c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019dbe1b-788d-708d-844a-9527e3d9fc83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019dbe1b-788d-7bff-a027-4d83e5fdbb6c" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019dbe1b-788d-708d-844a-9527e3d9fc83" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019dbe1b-788d-7e05-a9bf-2182f9b96240" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019dbe1b-788d-708d-844a-9527e3d9fc83" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019dbe1b-788d-7e05-a9bf-2182f9b96240" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019dbe1b-788d-7a5e-8010-3f636341a1da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-714c-ba49-8fabdacad396" xlink:to="loc_us-gaap_RestructuringCharges_019dbe1b-788d-7a5e-8010-3f636341a1da" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/RESTRUCTURINGScheduleofRestructuringReserveActivityDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#RESTRUCTURINGScheduleofRestructuringReserveActivityDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/RESTRUCTURINGScheduleofRestructuringReserveActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-7ce1-a322-2dcca3f958a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7435-999f-e791c4c57f12" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-7ce1-a322-2dcca3f958a7" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7435-999f-e791c4c57f12" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019cb4d6-88bf-746c-8f88-4c9d6865947e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7435-999f-e791c4c57f12" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019cb4d6-88bf-746c-8f88-4c9d6865947e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019cb4d6-88bf-746c-8f88-4c9d6865947e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019cb4d6-88bf-746c-8f88-4c9d6865947e" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019cb4d6-88bf-746c-8f88-4c9d6865947e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019cb4d6-88bf-77b3-b19c-fb122ea2f698" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019cb4d6-88bf-746c-8f88-4c9d6865947e" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019cb4d6-88bf-77b3-b19c-fb122ea2f698" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019cb4d6-88bf-75b8-8642-9cb3afe41fac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019cb4d6-88bf-77b3-b19c-fb122ea2f698" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019cb4d6-88bf-75b8-8642-9cb3afe41fac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7694-ba33-06aa651e08e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cb4d6-88bf-7435-999f-e791c4c57f12" xlink:to="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7694-ba33-06aa651e08e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7694-ba33-06aa651e08e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7694-ba33-06aa651e08e9" xlink:to="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7694-ba33-06aa651e08e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7131-8c59-72ec3b9095ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_019cb4d6-88bf-7694-ba33-06aa651e08e9" xlink:to="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7131-8c59-72ec3b9095ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_A2026WorkforceReductionPlanMember_019cb4d6-88bf-7f13-bbc8-257237d2136e" xlink:href="bmrn-20260331.xsd#bmrn_A2026WorkforceReductionPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_019cb4d6-88bf-7131-8c59-72ec3b9095ff" xlink:to="loc_bmrn_A2026WorkforceReductionPlanMember_019cb4d6-88bf-7f13-bbc8-257237d2136e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_019cb4d6-88bf-7974-9548-e8c8f034f80b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cb4d6-88bf-7ce1-a322-2dcca3f958a7" xlink:to="loc_us-gaap_RestructuringReserveRollForward_019cb4d6-88bf-7974-9548-e8c8f034f80b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019cb4d6-88bf-784c-b49f-670b37e11d57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019cb4d6-88bf-7974-9548-e8c8f034f80b" xlink:to="loc_us-gaap_RestructuringReserve_019cb4d6-88bf-784c-b49f-670b37e11d57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019cb4d6-88bf-76ed-9d27-b33e1cd58e80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019cb4d6-88bf-7974-9548-e8c8f034f80b" xlink:to="loc_us-gaap_RestructuringCharges_019cb4d6-88bf-76ed-9d27-b33e1cd58e80" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019cb4d6-88bf-7098-b61c-2af0a56d23e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019cb4d6-88bf-7974-9548-e8c8f034f80b" xlink:to="loc_us-gaap_PaymentsForRestructuring_019cb4d6-88bf-7098-b61c-2af0a56d23e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_019cb4d6-88bf-771a-ad4b-4a5804c73823" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserve"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/EARNINGSPERCOMMONSHAREScheduleofComputationofBasicandDilutedEarningsPerCommonShareDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#EARNINGSPERCOMMONSHAREScheduleofComputationofBasicandDilutedEarningsPerCommonShareDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/EARNINGSPERCOMMONSHAREScheduleofComputationofBasicandDilutedEarningsPerCommonShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019cb4d6-8814-749b-9e47-ca83aaa42161" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019cb4d6-8814-749b-9e47-ca83aaa42161" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019cb4d6-8814-7e65-8860-26e6dfc8f766" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019cb4d6-8814-749b-9e47-ca83aaa42161" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019cb4d6-8814-7e65-8860-26e6dfc8f766" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7e65-8860-26e6dfc8f766_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019cb4d6-8814-7e65-8860-26e6dfc8f766" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7e65-8860-26e6dfc8f766_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7c60-804e-8a9576e9813c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019cb4d6-8814-7e65-8860-26e6dfc8f766" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7c60-804e-8a9576e9813c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019cb4d6-8814-740d-b6a6-eea761893f7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7c60-804e-8a9576e9813c" xlink:to="loc_us-gaap_StockCompensationPlanMember_019cb4d6-8814-740d-b6a6-eea761893f7f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_CommonStockIssuableUnderConvertibleDebtMember_019cb4d6-8814-74d2-af21-5d0d538325fd" xlink:href="bmrn-20260331.xsd#bmrn_CommonStockIssuableUnderConvertibleDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019cb4d6-8814-7c60-804e-8a9576e9813c" xlink:to="loc_bmrn_CommonStockIssuableUnderConvertibleDebtMember_019cb4d6-8814-74d2-af21-5d0d538325fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019cb4d6-8814-7da4-a5cb-52629b358e94" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019cb4d6-8814-7da4-a5cb-52629b358e94" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019cb4d6-8814-7d55-9dd2-4704ce03df88" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019cb4d6-8814-7da4-a5cb-52629b358e94" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic_019cb4d6-8814-7d55-9dd2-4704ce03df88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestOnConvertibleDebtNetOfTax_019cb4d6-8814-7622-9a33-027ab5d62b71" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestOnConvertibleDebtNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019cb4d6-8814-7da4-a5cb-52629b358e94" xlink:to="loc_us-gaap_InterestOnConvertibleDebtNetOfTax_019cb4d6-8814-7622-9a33-027ab5d62b71" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019cb4d6-8814-75d8-8ad7-adb0d0e1f5c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersBasicAbstract_019cb4d6-8814-7da4-a5cb-52629b358e94" xlink:to="loc_us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted_019cb4d6-8814-75d8-8ad7-adb0d0e1f5c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019cb4d6-8814-7b0a-be72-480564da33bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019cb4d6-8814-7b0a-be72-480564da33bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cb4d6-8814-79fe-80c5-c595a5c14605" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019cb4d6-8814-7b0a-be72-480564da33bf" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019cb4d6-8814-79fe-80c5-c595a5c14605" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DilutiveSecuritiesAbstract_019cb4d6-8814-76aa-bd22-a18625342a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DilutiveSecuritiesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019cb4d6-8814-7b0a-be72-480564da33bf" xlink:to="loc_us-gaap_DilutiveSecuritiesAbstract_019cb4d6-8814-76aa-bd22-a18625342a8f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_019cb4d6-8814-7897-a9fb-5c0553edfcd7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DilutiveSecuritiesAbstract_019cb4d6-8814-76aa-bd22-a18625342a8f" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToConversionOfDebtSecurities_019cb4d6-8814-7897-a9fb-5c0553edfcd7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cb4d6-8814-751a-a1fd-d7e3d16f9441" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_019cb4d6-8814-7b0a-be72-480564da33bf" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019cb4d6-8814-751a-a1fd-d7e3d16f9441" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019cb4d6-8814-78ad-ae08-707fdf426f95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:to="loc_us-gaap_EarningsPerShareBasic_019cb4d6-8814-78ad-ae08-707fdf426f95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019cb4d6-8814-72ce-87a1-f83beb10a169" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019cb4d6-8814-79d9-8c57-16739983eb9c" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019cb4d6-8814-72ce-87a1-f83beb10a169" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.bmrn.com/role/SUBSEQUENTEVENTSDetails" xlink:type="simple" xlink:href="bmrn-20260331.xsd#SUBSEQUENTEVENTSDetails"/>
  <link:definitionLink xlink:role="http://www.bmrn.com/role/SUBSEQUENTEVENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019de55b-3da7-738a-9166-4cb82f066de0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019de55b-3da7-738a-9166-4cb82f066de0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de55b-3da7-738a-9166-4cb82f066de0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019de55b-3da7-738a-9166-4cb82f066de0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de55b-3da7-738a-9166-4cb82f066de0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de55b-3da7-73a0-ab2e-d61040099149" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019de55b-3da7-738a-9166-4cb82f066de0" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de55b-3da7-73a0-ab2e-d61040099149" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_AmicusTherapeuticsMember_019de55b-3da7-7d25-bfff-6a5deaec5444" xlink:href="bmrn-20260331.xsd#bmrn_AmicusTherapeuticsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019de55b-3da7-73a0-ab2e-d61040099149" xlink:to="loc_bmrn_AmicusTherapeuticsMember_019de55b-3da7-7d25-bfff-6a5deaec5444" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019de55b-3da7-731c-b256-3447bfbab0ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019de55b-3da7-731c-b256-3447bfbab0ed" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019de55b-3da7-731c-b256-3447bfbab0ed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019de55b-3da7-731c-b256-3447bfbab0ed" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019de55b-3da7-731c-b256-3447bfbab0ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019de55b-3da7-7b2c-a27a-38ab8b92ccce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019de55b-3da7-731c-b256-3447bfbab0ed" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019de55b-3da7-7b2c-a27a-38ab8b92ccce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019de55b-3da7-751a-9b6a-16b0180dbc4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019de55b-3da7-7b2c-a27a-38ab8b92ccce" xlink:to="loc_us-gaap_SubsequentEventMember_019de55b-3da7-751a-9b6a-16b0180dbc4c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019de55b-3da7-7cbb-be01-6243416dd16a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_CreditFacilityAxis_019de55b-3da7-7cbb-be01-6243416dd16a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7cbb-be01-6243416dd16a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019de55b-3da7-7cbb-be01-6243416dd16a" xlink:to="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7cbb-be01-6243416dd16a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7e8a-9aa0-144d089745b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019de55b-3da7-7cbb-be01-6243416dd16a" xlink:to="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7e8a-9aa0-144d089745b3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebtMember_019de55b-3da7-7980-ab2b-863c57264feb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7e8a-9aa0-144d089745b3" xlink:to="loc_us-gaap_SecuredDebtMember_019de55b-3da7-7980-ab2b-863c57264feb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019de55b-3da7-7e4a-9e9b-462c2ea31003" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019de55b-3da7-7e8a-9aa0-144d089745b3" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019de55b-3da7-7e4a-9e9b-462c2ea31003" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019de55b-3da7-7436-a12a-7267189486b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_DebtInstrumentAxis_019de55b-3da7-7436-a12a-7267189486b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-7436-a12a-7267189486b0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019de55b-3da7-7436-a12a-7267189486b0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-7436-a12a-7267189486b0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-761c-a2c2-ea45946b6abb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019de55b-3da7-7436-a12a-7267189486b0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-761c-a2c2-ea45946b6abb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_SeniorSecuredTermLoanFacilityMember_019de55b-3da7-7a32-adae-e7b720c18aa0" xlink:href="bmrn-20260331.xsd#bmrn_SeniorSecuredTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-761c-a2c2-ea45946b6abb" xlink:to="loc_bmrn_SeniorSecuredTermLoanFacilityMember_019de55b-3da7-7a32-adae-e7b720c18aa0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_SeniorSecuredRevolvingCreditFacilityMember_019de55b-3da7-7871-b8d9-2294c568c7c2" xlink:href="bmrn-20260331.xsd#bmrn_SeniorSecuredRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-761c-a2c2-ea45946b6abb" xlink:to="loc_bmrn_SeniorSecuredRevolvingCreditFacilityMember_019de55b-3da7-7871-b8d9-2294c568c7c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_A364DaySeniorSecuredBridgeFacilityMember_019de55b-3da7-7ae3-927e-79f02c1887fc" xlink:href="bmrn-20260331.xsd#bmrn_A364DaySeniorSecuredBridgeFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019de55b-3da7-761c-a2c2-ea45946b6abb" xlink:to="loc_bmrn_A364DaySeniorSecuredBridgeFacilityMember_019de55b-3da7-7ae3-927e-79f02c1887fc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019de55b-3da7-7428-84d6-182321a81650" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019de55b-3da7-7428-84d6-182321a81650" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019de55b-3da7-7428-84d6-182321a81650_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019de55b-3da7-7428-84d6-182321a81650" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019de55b-3da7-7428-84d6-182321a81650_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019de55b-3da7-7f95-ab6b-757b51efc327" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019de55b-3da7-7428-84d6-182321a81650" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019de55b-3da7-7f95-ab6b-757b51efc327" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019de55b-3da7-7f75-b1aa-bcc4483ec05c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019de55b-3da7-7f95-ab6b-757b51efc327" xlink:to="loc_us-gaap_LineOfCreditMember_019de55b-3da7-7f75-b1aa-bcc4483ec05c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_019de55b-3da7-7466-a8cc-5e907ab97951" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019de55b-3da7-7107-a928-8ed4e1effe91" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_019de55b-3da7-7466-a8cc-5e907ab97951" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019de55b-3da7-7466-a8cc-5e907ab97951_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019de55b-3da7-7466-a8cc-5e907ab97951" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019de55b-3da7-7466-a8cc-5e907ab97951_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_019de55b-3da7-7365-9711-667f86d19c15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_019de55b-3da7-7466-a8cc-5e907ab97951" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_019de55b-3da7-7365-9711-667f86d19c15" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BridgeLoanMember_019de55b-3da7-719d-8348-1430fe6f87fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BridgeLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_019de55b-3da7-7365-9711-667f86d19c15" xlink:to="loc_us-gaap_BridgeLoanMember_019de55b-3da7-719d-8348-1430fe6f87fd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionSharePrice_019de55b-3da7-73fe-a6b6-a0ff493c06d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionSharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_BusinessAcquisitionSharePrice_019de55b-3da7-73fe-a6b6-a0ff493c06d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019de55b-3da7-7cba-9df9-d1073b7717ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_019de55b-3da7-7cba-9df9-d1073b7717ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_BusinessCombinationRecognizedLiabilityAssumedLoans_019de55b-3da7-7ede-a52d-d58f130266b1" xlink:href="bmrn-20260331.xsd#bmrn_BusinessCombinationRecognizedLiabilityAssumedLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_bmrn_BusinessCombinationRecognizedLiabilityAssumedLoans_019de55b-3da7-7ede-a52d-d58f130266b1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_bmrn_BusinessCombinationNumberOfTreatmentTherapiesAcquired_019de55b-3da7-7754-ac93-19462d7f8497" xlink:href="bmrn-20260331.xsd#bmrn_BusinessCombinationNumberOfTreatmentTherapiesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_bmrn_BusinessCombinationNumberOfTreatmentTherapiesAcquired_019de55b-3da7-7754-ac93-19462d7f8497" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019de55b-3da7-7639-ad55-a357b5de448d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019de55b-3da7-7639-ad55-a357b5de448d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019de55b-3da7-7678-811c-9c175101b976" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019de55b-3da7-7678-811c-9c175101b976" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFeeAmount_019df74f-c924-7102-ac92-065995dfbb67" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFeeAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019de55b-3da7-7d32-a3a0-74a2c482a995" xlink:to="loc_us-gaap_DebtInstrumentFeeAmount_019df74f-c924-7102-ac92-065995dfbb67" xlink:type="arc" order="6"/>
  </link:definitionLink>
</link:linkbase>
