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 of the

Securities Exchange Act of 1934

For the month of October, 2026

Commission File Number 1-15106

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 – 9th floor 
20231-030 – Rio de Janeiro, RJ
Federative Republic of Brazil

(Address of principal executive office)

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

Form 20-F ___X___ Form 40-F _______

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes _______ No___X____

Petrobras completes drilling with another oil discovery in Ultra-Deep Waters off the Coast of Amapá

—

Rio de Janeiro, October 29, 2026 – Petróleo Brasileiro S.A. - Petrobras, following the Notices to the Market disclosed on August 14 and October 22, 2026, informs that it has identified another oil-bearing interval in the Morpho well, which constitutes the third discovery in block FZA-M-59, located in ultra-deep waters off the coast of the state of Amapá, at a water depth of 2,886 meters.

The continued evaluation of other intervals of interest, following the discoveries announced in August and early October 2026, allowed the confirmation of this new discovery.

Drilling and the acquisition of geological data have been completed. The only remaining step is the completion of well operations (abandonment), after which the rig will proceed to the Potiguar Basin, off the coast of Rio Grande do Norte, where it will begin drilling at the Mãe de Ouro location.

Petrobras' activities in block FZA-M-59 are aligned with the company's long-term strategy of replenishing its oil and gas reserves through the exploration of new frontiers, contributing to meeting the country's energy demand.

www.petrobras.com.br/ir

For more information:

PETRÓLEO BRASILEIRO S.A. – PETROBRAS | Investor Relations

Email: petroinvest@petrobras.com.br/acionistas@petrobras.com.br

Av. Henrique Valadares, 28 – 9th floor – 20231-030 – Rio de Janeiro, RJ.

Tel.: 55 (21) 3224-1510/9947

This document may contain forecasts within the meaning of Section 27A of the Securities Act of 1933, as amended (Securities Act), and Section 21E of the Securities Trading Act of 1934, as amended (Trading Act) that reflect the expectations of the Company's officers. The terms: "anticipates", "believes", "expects", "predicts", "intends", "plans", "projects", "aims", "should," and similar terms, aim to identify such forecasts, which evidently involve risks or uncertainties, predicted or not by the Company. Therefore, future results of the Company's operations may differ from current expectations, and the reader should not rely solely on the information included herein.

SIGNATURES

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: October 29, 2026

PETRÓLEO BRASILEIRO S.A–PETROBRAS

By: /s/ Fernando Sabbi Melgarejo

______________________________

Fernando Sabbi Melgarejo

Chief Financial Officer and Investor Relations Officer