Company: SUZ
Filing Date: 2025-09-05
Form Type: 6-K
Source: 0001104659-25-087544
Chunk: 0

Company: Suzano S.A.
Filing Date: 2025-09-05
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 ofSeptember 2025.

Commission File Number001-38755

SuzanoS.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-Fx Form
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): ¨

<div align='center'>1</div>

This report and exhibit 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to the SEC, to the extent not superseded by documents or reports subsequently filed or furnished.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 1.1 — Underwriting Agreement |
| Exhibit 1.2 — Terms Agreement        |

<div align='center'>2</div>

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, thereunto duly authorized.

Date:September
3, 2025

| SUZANO S.A. |                                    |                                                            |
| By:         | /s/ Marcos Moreno Chagas Assumpção |                                                            |
|             | Name:                              | Marcos Moreno Chagas Assumpção