UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 6-K
Report of Foreign Issuer
Pursuant To Rule 13a-16 Or 15d-16 of the
Securities Exchange Act of 1934
For the month of October 2025
Commission File Number: 333-251238
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COSAN S.A.
(Exact name of registrant as specified in its charter)
N/A
(Translation of registrant’s name into English)
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Av. Brigadeiro Faria Lima, 4100, – 16th floor
São Paulo, SP 04538-132 Brazil
(Address of principal executive offices)
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 ☒ 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 ☒
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 ☒

COSAN S.A.
CNPJ No. 50.746.577/0001-15
NIRE 35.300.177.045
Publicly-held company
CVM Code 19836
MATERIAL FACT
COSAN S.A. (B3: CSAN3; NYSE: CSAN) ("Cosan" or "Company"), in compliance with the provisions of CVM Resolution No. 44, of August 23, 2021, in the context of the Material Fact disclosed on September 21, 2025, hereby informs its shareholders and the market in general that the Conselho Administrativo de Defesa Econômica ("CADE") has approved without restrictions the subscription of shares issued by Cosan, by the funds Perfin Rally Fundo de Investimento em Participações Multiestratégia Responsabilidade Limitada, Classe Única BTG Pactual Infraestrutura III Fundo de Investimento em Participações Multiestratégia, and Classe Única Fundo de Investimento em Participações BPAC3 - Multiestratégia Responsabilidade Limitada (collectively, "Investors"). The eventual subscription of the shares by the Investors, under the terms of the Investment Agreement, depends on the conclusion and allocation in the first public offering in progress.
CADE's decision is still awaiting the expiration of the legal period of 15 days, under the terms of the applicable legislation.
The Company will keep its shareholders and the market informed about the conclusion of the first public offering, whose closing of the Bookbuilding Procedure is expected to take place on November 3, 2025, pursuant to the law and CVM regulations. More information may be obtained in due course on the CVM (www.gov.br/cvm) and the Company's Investor Relations (www.cosan.com.br) websites.
São Paulo, October 30, 2025.
Rodrigo Araujo Alves
Chief Financial and Investor Relations Officer
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 30, 2025
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COSAN S.A. |
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By: |
/s/ Rodrigo Araujo Alves |
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Name: Rodrigo Araujo Alves |
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Title: Chief Financial Officer |
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