<SUBMISSION>
<ACCESSION-NUMBER>0001140361-09-019951
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20090828
<FILING-DATE>20090828
<DATE-OF-FILING-DATE-CHANGE>20090828
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>U.S. Auto Parts Network, Inc.
<CIK>0001378950
<ASSIGNED-SIC>5531
<IRS-NUMBER>680623433
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0102
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>17150 SOUTH MARGAY AVENUE
<CITY>CARSON
<STATE>CA
<ZIP>90746
<PHONE>(310) 715-6666
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>17150 SOUTH MARGAY AVENUE
<CITY>CARSON
<STATE>CA
<ZIP>90746
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>SANDERS THEODORE R
<CIK>0001244638
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33264
<FILM-NUMBER>091044305
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O VIEWSONIC CORPORATION
<STREET2>381 BREA CANYON ROAD
<CITY>WALNUT
<STATE>CA
<ZIP>91789
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-08-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001378950</issuerCik>
        <issuerName>U.S. Auto Parts Network, Inc.</issuerName>
        <issuerTradingSymbol>PRTS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001244638</rptOwnerCik>
            <rptOwnerName>SANDERS THEODORE R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O US AUTO PARTS NETWORK, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>17150 MARGAY AVENUE</rptOwnerStreet2>
            <rptOwnerCity>CARSON</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90746</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-08-28</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2009-08-28</value>
            </deemedExecutionDate>
            <transactionCoding>
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                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15100</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            </deemedExecutionDate>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
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            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>5.21</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
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                </directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
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            </transactionDate>
            <deemedExecutionDate>
                <value>2009-08-28</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3155</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.30</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>20000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Theodore R. Sanders</signatureName>
        <signatureDate>2009-08-28</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
