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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-05-05</periodOfReport>

    <issuer>
        <issuerCik>0001004980</issuerCik>
        <issuerName>PG&amp;E Corp</issuerName>
        <issuerTradingSymbol>PCG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001167316</rptOwnerCik>
            <rptOwnerName>EARLEY ANTHONY F JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PG&amp;E CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>77 BEALE ST., P.O. BOX 770000</rptOwnerStreet2>
            <rptOwnerCity>SAN FRANCISCO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94177</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <officerTitle>Executive Chair</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-05-05</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>17874</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>365166</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1251.98</value>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by Trustee of PG&amp;E Corporation Retirement Savings Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the PG&amp;E Corporation Equity Grant Date Policy, which is described in the proxy statement filed by PG&amp;E Corporation with the Securities Exchange Commission on April 18, 2017, the grant date of restricted stock units (RSUs) and performance shares approved on February 14, 2017 was May 5, 2017, instead of March 1, 2017.</footnote>
        <footnote id="F2">RSUs granted under the PG&amp;E Corporation 2014 Long-Term Incentive Plan.  RSUs are payable on shares of PG&amp;E Corporation common stock on a one-for-one basis.</footnote>
        <footnote id="F3">Represents the approximate number of shares of PG&amp;E Corporation common stock held for the reporting person in the PG&amp;E Corporation Stock Fund of the PG&amp;E Corporation Retirement Savings Plan (RSP).  That fund holds units consisting of PG&amp;E Corporation common stock and a small short-term investments component.  The number of shares is computed by dividing the value of the units by the daily closing price.  Dividends are automatically invested in additional units at the election of the participant.  These holdings have been trued up to conform to the RSP balance as of 5/5/17, and reflect the acquisition of approximately 8.74 shares on 4/17/17 due to dividend reinvestment.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Eileen O. Chan, attorney-in-fact for Anthony F. Earley, Jr. (signed Power of Attorney on file with SEC)</signatureName>
        <signatureDate>2017-05-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
