Company: SUZ
Filing Date: 2025-09-11
Form Type: 6-K
Source: 0001104659-25-089141
Chunk: 0

Company: Suzano S.A.
Filing Date: 2025-09-11
Form: 6-K
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

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

THE SECURITIES EXCHANGE ACT OF 1934

For the month of September 2025.

Commission File Number 001-38755

Suzano S.A.

(Exact name of registrant as specified in its charter)

SUZANO INC.

(Translation of Registrant’s Name into English)

Av. Professor Magalhaes Neto, 1,752

10th Floor, Rooms 1010 and 1011

Salvador, Brazil 41 810-012

(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.

<div align='center'>Form 20-FxForm 40-F ¨</div>

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): ¨

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): ¨

This report and exhibits are incorporated by reference
into the Registration Statement on Form F-3 of Suzano S.A. (No. 333- 286881) and Suzano Netherlands B.V. (No. 333- 286881-02),
and shall be deemed to be a part thereof from the date on which this report is furnished to the SEC, to the extent not superseded by documents
or reports subsequently filed or furnished.

| Exhibit 4.1 — Base Indenture, dated September 10, 2025                                       
 Exhibit 4.2 — First Supplemental Indenture, dated September 10, 2025                         |
|:---------------------------------------------------------------------------------------------|
| Exhibit 4.3 — Form of Global Notes (included in Exhibit 4.2)                                 |
| Exhibit 5.1 — Opinion of Machado, Meyer, Sendacz e Opice Advogados, dated September 10, 2025 |
| Exhibit 5.2 — Opinion of Norton Rose Fulbright LLP, dated September 10, 2025                 |
| Exhibit 5.3 —