<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2021-08-25</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001819994</issuerCik>
        <issuerName>Rocket Lab USA, Inc.</issuerName>
        <issuerTradingSymbol>RKLB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001551426</rptOwnerCik>
            <rptOwnerName>KHOSLA VENTURES SEED B, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001551427</rptOwnerCik>
            <rptOwnerName>KHOSLA VENTURES SEED B (CF), L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001845461</rptOwnerCik>
            <rptOwnerName>Khosla Ventures Seed Associates B, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001611146</rptOwnerCik>
            <rptOwnerName>Khosla Ventures V, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001611145</rptOwnerCik>
            <rptOwnerName>Khosla Ventures Associates V, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001501927</rptOwnerCik>
            <rptOwnerName>VK Services, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001032453</rptOwnerCik>
            <rptOwnerName>KHOSLA VINOD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2128 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>53762806</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3051809</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>58190180</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Earnout Rights (Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4344527</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Earnout Rights (Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>246614</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Earnout Rights (Common Stock)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F4"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4702300</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Consists of securities held of record by Khosla Ventures Seed B, L.P. (&quot;KV Seed B&quot;), of which Khosla Ventures Seed Associates B, LLC (&quot;KVA Seed B&quot;) is the general partner. Vinod Khosla is the managing member of VK Services, LLC (&quot;VK Services&quot;), which is the sole manager of KVA Seed B. Each of KVA Seed B, VK Services and Vinod Khosla may be deemed to possess voting and investment control over such securities held by KV Seed B, and each of KVA Seed B, VK Services and Vinod Khosla may be deemed to have indirect beneficial ownership of such securities held by KV Seed B. Each Reporting Person disclaims beneficial ownership of such shares except to the extent of his or its respective pecuniary interests therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F2">Consists of securities held of record by Khosla Ventures Seed B (CF), L.P. (&quot;KV Seed B (CF)&quot;), of which KVA Seed B is the general partner. Vinod Khosla is the managing member of VK Services, which is the sole manager of KVA Seed B. Each of KVA Seed B, VK Services and Vinod Khosla may be deemed to possess voting and investment control over such securities held by KV Seed B (CF), and each of KVA Seed B, VK Services and Vinod Khosla may be deemed to have indirect beneficial ownership of such securities held by KV Seed B (CF). Each Reporting Person disclaims beneficial ownership of such shares except to the extent of his or its respective pecuniary interests therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F3">Consists of securities held of record by Khosla Ventures V, L.P. (&quot;KV V&quot;), of which Khosla Ventures Associates V, LLC (&quot;KVA V&quot;) is the general partner. Vinod Khosla is the managing member of VK Services, which is the sole manager of KVA V. Each of KVA V, VK Services and Vinod Khosla may be deemed to possess voting and investment control over such securities held by KV V, and each of KVA V, VK Services, and Vinod Khosla may be deemed to have indirect beneficial ownership of such securities held by KV V. Each Reporting Person disclaims beneficial ownership of such shares except to the extent of his or its pecuniary interests therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of the reported securities for purposes of Section 16 or for any other purposes.</footnote>
        <footnote id="F4">Each earnout right represents a contingent right (based on the Reporting Person's ownership of common stock) to receive one share of the Issuer's common stock. The earnout rights were issued in connection with a business combination of the Issuer (the &quot;Business Combination&quot;). The earnout rights vest upon the Issuer's common stock achieving a closing price per share equal to or greater than $20.00 for a period of at least 20 trading days out of 30 consecutive trading days during the period commencing on the 90th day following August 25, 2021 and ending on the 180th day following August 25, 2021. If the target closing price of the common stock is not achieved during such period, the earnout rights will be forfeited. The Reporting Person's right to receive additional shares of common stock pursuant to this earnout right became fixed and irrevocable on August 25, 2021, the effective date of the Business Combination.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC, in its capacity as Manager of Khosla Ventures Seed Associates B, LLC, in its capacity as general partner of Khosla Ventures Seed B, L.P.</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC, in its capacity as Manager of Khosla Ventures Seed Associates B, LLC, in its capacity as general partner of Khosla Ventures Seed B (CF), L.P.</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC, in its capacity as Manager of Khosla Ventures Seed Associates B, LLC</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC, in its capacity as Manager of Khosla Ventures Associates V, LLC, in its capacity as general partner of Khosla Ventures V, L.P.</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC, in its capacity as Manager of Khosla Ventures Associates V, LLC</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla, as Managing Member of VK Services, LLC</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ John J. Demeter, as attorney in fact for Vinod Khosla</signatureName>
        <signatureDate>2021-09-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
