content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <!-- Generated by Workiva -->
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001779899</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001709682</issuerCik>
        <issuerName>Custom Truck One Source, Inc.</issuerName>
        <secFileNumber>001-38186</secFileNumber>
        <issuerAddress>
          <com:street1>7701 Independence Avenue</com:street1>
          <com:city>Kansas City</com:city>
          <com:stateOrCountry>MO</com:stateOrCountry>
          <com:zipCode>64125</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>816-241-4888</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Nesco Holdings, L.P.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Former Director</relationshipToIssuer>
          <relationshipToIssuer>10% Shareholder</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>J.P. Morgan Securities LLC</name>
          <address>
            <com:street1>390 Madison Avenue</com:street1>
            <com:street2>6th Floor</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>1942535</noOfUnitsSold>
        <aggregateMarketValue>7381633</aggregateMarketValue>
        <noOfUnitsOutstanding>236210901</noOfUnitsOutstanding>
        <approxSaleDate>09/05/2024</approxSaleDate>
        <securitiesExchangeName>NYSE</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>07/31/2019</acquiredDate>
        <natureOfAcquisitionTransaction>Merger</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>1942535</amountOfSecuritiesAcquired>
        <paymentDate>07/31/2019</paymentDate>
        <natureOfPayment>N/A</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>09/05/2024</noticeDate>
        <signature>/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Nesco Holdings, L.P.</signature>
      </noticeSignature>
    </formData>
  </edgarSubmission>
metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 2950}]
text: 144
  0001779899
  XXXXXXXX
  LIVE
  0001709682
  Custom Truck One Source, Inc.
  001-38186
  7701 Independence Avenue
  Kansas City
  MO
  64125
  816-241-4888
  Nesco Holdings, L.P.
  Former Director
  10% Shareholder
  Common Stock
  J.P. Morgan Securities LLC
  390 Madison Avenue
  6th Floor
  New York
  NY
  10017
  1942535
  7381633
  236210901
  09/05/2024
  NYSE
  Common Stock
  07/31/2019
  Merger
  Issuer
  N
  1942535
  07/31/2019
  N/A
  Y
  09/05/2024
  /s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Nesco Holdings, L.P.