PBR 6-K

UNITEDSTATES

SECURITIESAND EXCHANGE COMMISSION

Washington,D.C. 20549

FORM6-K

REPORTOF FOREIGN PRIVATE ISSUER

PURSUANTTO RULE 13a-16 OR 15d-16

UNDERTHE SECURITIES EXCHANGE ACT OF 1934

Forthe month of September, 2025

CommissionFile Number 001-15106

PETRÓLEOBRASILEIRO S.A. - PETROBRAS

(Exact name of registrant as specified in its charter)

BrazilianPetroleum Corporation - PETROBRAS

(Translation of Registrant's name into English)

AvenidaHenrique Valadares, 28 20241-030 - Rio de Janeiro, RJFederative Republic of Brazil

(Address of principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F x Form 40-F ¨

PETROBRASANNOUNCES OFFERING OF U.S. DOLLAR-DENOMINATED GLOBAL NOTES

RIO DEJANEIRO, BRAZIL – SEPTEMBER 3, 2025 – Petróleo Brasileiro S.A. – Petrobras (“Petrobras”) (NYSE: PBR) announces that its wholly-owned subsidiary, Petrobras Global Finance B.V. (“PGF”), has commenced an offering of two new series of U.S. dollar-denominated global notes in the international capital markets (the “Notes”), subject to market and other conditions. The Notes will be unsecured obligations of PGF and will be fully, unconditionally and irrevocably guaranteed by Petrobras.

PGF intends to use the net proceeds from the sale of the Notes for general corporate purposes.

PGF has engaged BBVA Securities Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., Itau BBA USA Securities, Inc., Santander US Capital Markets LLC and UBS Investment Bank to act as joint bookrunners with respect to the offering of the Notes.

This announcement is for informational purposes only, and does not constitute or form part of any offer or invitation to sell or a solicitation of an offer to purchase any securities.

There shall be no sale of the Notes in any jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. PGF and Petrobras have filed a registration statement, including a prospectus with the U.S. Securities and Exchange Commission (“SEC”). Before you invest, you should read the prospectus and preliminary prospectus supplement and other documents PGF and Petrobras have filed with the SEC for more complete information about the companies and the offering of the Notes. When available, you may access these documents for free by visiting EDGAR on the SEC web site at www.sec.gov. Alternatively, a copy of the prospectus and preliminary prospectus supplement may be obtained by contacting BBVA Securities Inc. at +1 (212) 728-2300, Citigroup Global Markets Inc. toll-free at +1 (800) 831-9146, Deutsche Bank Securities Inc. toll-free (U.S. only) at +1 (800) 503-4611, Itau BBA USA Securities, Inc. collect at +1 (212) 710-6749 or toll-free (U.S. only) at +1 (888) 770-4828, Santander US Capital Markets LLC toll-free (U.S. only) at +1 (855) 403-3636, and UBS Investment Bank toll-free (U.S. only) at +1 (833) 481-0269.

The Notesare not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to anyretail investor in the European Economic Area (“EEA”). For these purposes, a retail investor means a person who is one (ormore) of: (i) a retail client as defined in point (11) of Article 4(1) of Directive 2014/65/EU (as amended, “MiFID II”);or (ii) a customer within the meaning of Directive (EU) 2016/97 (as amended, the “Insurance Distribution Directive”), wherethat customer would not qualify as a professional client as defined in point (10) of Article 4(1) of MiFID II; or (iii) not a qualifiedinvestor as defined in Regulation (EU) 2017/1129 (as amended, the “Prospectus Regulation”); and the expression “offer”includes the communication in any form and by any means of sufficient information on the terms of the offer and the Notes to be offeredso as to enable an investor to decide to purchase or subscribe the Notes. Consequently, no key information document required by Regulation(EU) No 1286/2014 (as amended, the “PRIIPs Regulation”) for offering or selling the Notes or otherwise making them availableto retail investors in the EEA has been prepared and the Notes will not be offered or sold or otherwise made available to any retailinvestor in the EEA.

Each personin a Member State of the EEA who acquires any Notes under, the offers to the public contemplated in the Note offering, or to whom theNotes are otherwise made available, will be deemed to have represented, warranted, acknowledged and agreed to and with each underwriterand PGF that it and any person on whose behalf it acquires Notes is: (1) a “qualified investor” within the meaning of theProspectus Regulation; and (2) not a “retail investor” (as defined above).

The Notesare not intended to be offered, sold or otherwise made available to and should not be offered, sold or otherwise made available to anyretail investor in the United Kingdom (the “United Kingdom” or the “UK”). For these purposes, a retail investormeans a person who is one (or more) of: (i) a retail client, as defined in point (8) of Article 2 of Regulation (EU) No 2017/565 as itforms part of domestic law by virtue of the European Union (Withdrawal) Act 2018 (the “EUWA”); (ii) a customer within themeaning of the provisions of the Financial Services and Markets Act 2000 (the “FSMA”) and any rules or regulations made underthe FSMA to implement the Insurance Distribution Directive, where that customer would not qualify as a professional client, as definedin point (8) of Article 2(1) of Regulation (EU) No 600/2014 as it forms part of domestic law by virtue of the EUWA; or (iii) not a “qualifiedinvestor” as defined in Article 2 of the Prospectus Regulation as it forms part of the domestic law by virtue of the EUWA (the“UK Prospectus Regulation”). No key information document required by the PRIIPs Regulation as it forms part of domestic lawby virtue of the EUWA (the “UK PRIIPs Regulation”) for offering or selling the Notes or otherwise making them available toretail investors in the UK has been prepared and the Notes will not be offered or sold or otherwise made available to any retail investorin the UK.

Each personin the UK who acquires any Notes under, the offers to the public contemplated in the Notes offering, or to whom the Notes are otherwisemade available, will be deemed to have represented, warranted, acknowledged and agreed to and with each underwriter and PGF that it andany person on whose behalf it acquires Notes is: (1) a "qualified investor" within the meaning of the UK Prospectus Regulation;and (2) not a "retail investor" (as defined above).

The communicationof this announcement and any other documents or materials relating to the Notes offering is not being made and such documents and/ormaterials have not been approved by an authorized person for the purposes of Section 21 of the Financial Services and Markets Act 2000.This announcement and any other documents related to the Notes offering are for distribution only to persons who (i) have professionalexperience in matters relating to investments falling within Article 19(5) of the Financial Services and Markets Act 2000 (FinancialPromotion) Order 2005 (the “Order”), (ii) are persons falling within Article 49(2)(a) to (d) (“high net worth companies,unincorporated associations, etc.”) of the Order, (iii) are outside the United Kingdom, or (iv) are persons to whom an invitation or inducement to engagein investment activity (within the meaning of section 21 of the Financial Services and Markets Act 2000) in connection with the issue,or sale of any securities may otherwise lawfully be communicated or caused to be communicated (all such persons together being referredto as “relevant persons”). This announcement and any other documents related to the Notes offering are directed only at relevantpersons and must not be acted on or relied on by persons who are not relevant persons. Any investment or investment activity to whichthis press release and any other documents related to the Notes offering are available only to relevant persons and will be engaged inonly with relevant persons.

Forward-LookingStatements

This announcement contains forward-looking statements. Forward-looking statements are information of a non-historical nature or which relate to future events and are subject to risks and uncertainties. No assurance can be given that the transactions described herein will be consummated or as to the ultimate terms of any such transactions. Petrobras undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information or future events or for any other reason.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: September 3, 2025