content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001722291</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001097864</issuerCik>
        <issuerName>ON SEMICONDUCTOR CORP</issuerName>
        <secFileNumber>001-39317</secFileNumber>
        <issuerAddress>
          <com:street1>5701 NORTH PIMA ROAD</com:street1>
          <com:city>SCOTTSDALE</com:city>
          <com:stateOrCountry>AZ</com:stateOrCountry>
          <com:zipCode>85250</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>6022446600</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>GOPALSWAMY SUDHIR</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Rockefeller Capital Management</name>
          <address>
            <com:street1>1850 Mt Diablo Blvd</com:street1>
            <com:street2>Suite 300</com:street2>
            <com:city>Walnut Creek</com:city>
            <com:stateOrCountry>CO</com:stateOrCountry>
            <com:zipCode>94596</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>21082</noOfUnitsSold>
        <aggregateMarketValue>1426040.68</aggregateMarketValue>
        <noOfUnitsOutstanding>425797438</noOfUnitsOutstanding>
        <approxSaleDate>12/17/2024</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/20/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1410</amountOfSecuritiesAcquired>
        <paymentDate>02/20/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/06/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>4812</amountOfSecuritiesAcquired>
        <paymentDate>02/06/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/02/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>6323</amountOfSecuritiesAcquired>
        <paymentDate>02/02/2024</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>03/07/2023</acquiredDate>
        <natureOfAcquisitionTransaction>Stock Award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>8537</amountOfSecuritiesAcquired>
        <paymentDate>03/07/2023</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>12/17/2024</noticeDate>
        <signature> Jason Coleman as a duly authorized representative of National Financial Services LLC, as attorney-in-fact for Sudhir Gopalswamy </signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4482}]
text: 144
  0001722291
  XXXXXXXX
  LIVE
  0001097864
  ON SEMICONDUCTOR CORP
  001-39317
  5701 NORTH PIMA ROAD
  SCOTTSDALE
  AZ
  85250
  6022446600
  GOPALSWAMY SUDHIR
  Officer
  Common Stock
  Rockefeller Capital Management
  1850 Mt Diablo Blvd
  Suite 300
  Walnut Creek
  CO
  94596
  21082
  1426040.68
  425797438
  12/17/2024
  NASDAQ
  Common Stock
  02/20/2024
  Stock Award
  Issuer
  N
  1410
  02/20/2024
  Compensation
  Common Stock
  02/06/2024
  Stock Award
  Issuer
  N
  4812
  02/06/2024
  Compensation
  Common Stock
  02/02/2024
  Stock Award
  Issuer
  N
  6323
  02/02/2024
  Compensation
  Common Stock
  03/07/2023
  Stock Award
  Issuer
  N
  8537
  03/07/2023
  Compensation
  Y
  12/17/2024
  Jason Coleman as a duly authorized representative of National Financial Services LLC, as attorney-in-fact for Sudhir Gopalswamy