6-K

UNITED STATESSECURITIES 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: 001-34476

BANCO SANTANDER (BRASIL) S.A.

(Exact name of registrant as specified in its charter)

Avenida Presidente Juscelino Kubitschek, 2041 and 2235Bloco A – Vila OlimpiaSão Paulo, SP 04543-011Federative 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 _______

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes _______ No ___X____

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes _______ No ___X____

Indicate by check mark whether by furnishing the information contained in this Form, the Registrant 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____

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):  N/A

BANCO SANTANDER (BRASIL) S.A.

Public Company with Authorized Capital

Corporate Taxpayer´s Registry No. 90.400.888/0001-42

Company Registry No. 35.300.332.067

Minutesof the Board of Director’s Meeting

held onSeptember 16, 2025

DATE, TIME AND PLACE: On September 16, 2025, at 4:00 p.m., by videoconference, the Board of Directors of Banco Santander (Brasil) S.A. (“Company” or “Santander”) have met, with the attendance of all of its members.

CALL NOTICE AND NOTICE: The call notice was dismissed due to the attendance of the Directors fully representing the Company’s Board of Directors.

MEETING BOARD: Deborah Stern Vieitas, Chairman. Bruno Garcia Rosa Carneiro, Secretary.

AGENDA: To take resolution about the acknowledgment of the resignation of Mrs. Luciana de Aguiar Barros to the position of Officer without specific designation of the Company.

RESOLUTIONS: Made the necessary clarifications, the members of the Board of Directors unanimously: acknowledged the resignation, with effects from September 17^th^, 2025, request of Mrs. Luciana de Aguiar Barros, Brazilian, single, banker, bearer of identity card RG No. 32.756.618-8 SSP-SP, registered with the CPF/MF under No. 299.570.508-00, to the position of Officer without specific designation of the Company, pursuant to the Letter of Resignation filed at the Company's headquarters on September 15, 2025.

ADJOURNMENT: There being no further matters to be resolved, the Meeting was finalized, and these minutes have been prepared and send to be electronically signed by the attendees. Board: Deborah Stern Vieitas, Chairwoman. Bruno Garcia Rosa Carneiro, Secretary. Signatures: Mrs. Deborah Stern Vieitas – Chairwoman; Mr. Javier Maldonado Trinchant – Vice Chairman; and Messrs. Cristiana Almeida Pipponzi, Cristina San Jose Brosa, Deborah Patricia Wright, Ede Ilson Viani, José de Paiva Ferreira, Nitin Prabhu, Mario Roberto Opice Leão, Pedro Augusto de Melo and Vanessa de Souza Lobato Barbosa – Directors. São Paulo, September 16, 2025.

I certify that this is a true transcript of the minutes recorded in the Minutes of the Board of Directors Meetings Book of the Company.

Bruno Garcia Rosa Carneiro

Secretary

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, thereto duly authorized.

Date: September 16, 2025