Company: PBR
Filing Date: 2025-09-10
Form Type: 6-K
Source: 0001104659-25-089003
Chunk: 0

Company: PETROBRAS - PETROLEO BRASILEIRO SA
Filing Date: 2025-09-10
Form: 6-K
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

UNDER THE SECURITIES EXCHANGE ACT OF 1934

For the month of September, 2025

Commission File Number 001-15106

PETRÓLEO BRASILEIRO S.A. - PETROBRAS

(Exact name of registrant
as specified in its charter)

Brazilian Petroleum Corporation - PETROBRAS

(Translation of Registrant's
name into English)

Avenida Henrique Valadares, 28
20241-030 - Rio de Janeiro, RJ
Federative Republic of Brazil

(Address of principal
executive office)</div>

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 ¨

This report on Form 6-K shall be deemed to be incorporated by
reference into the Registration Statement on Form F-3 of Petróleo Brasileiro S.A. — Petrobras (No. 333-283981)
and Petrobras Global Finance B.V. – PGF (No. 333-283981-01) and the related prospectus supplement dated September 3,
2025.

Exhibit 4.1 — Guaranty for the 2030 Notes

Exhibit 4.2 — Guaranty for the 2036 Notes

Exhibit 4.3 — Seventh Supplemental Indenture

Exhibit 4.4 — Eighth Supplemental Indenture

Exhibit 4.5 — Form of 5.125% Global Notes due 2030 (included in Exhibit 4.3)

Exhibit 4.6 — Form of 6.250% Global Notes due 2036 (included in Exhibit 4.4)

Exhibit 5.1 — Opinion of internal counsel to Petrobras

Exhibit 5.2 — Opinion of Cleary Gottlieb Steen & Hamilton LLP, U.S. counsel to PGF and Petrobras

Exhibit 5.3 — Opinion of Heussen B.V., Dutch counsel to PGF

<div align='center'>SIGNATURE</div>

Pursuant to the requirements of the Securities
Exchange Act