Company: TNRSF
Filing Date: 2025-10-01
Form Type: 6-K
Source: 0001171843-25-006201
Chunk: 0

Company: TENARIS SA
Filing Date: 2025-10-01
Form: 6-K
Chunk 0
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<div align='center'>FORM 6 - K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

Pursuant to Rule 13a - 16 or 15d - 16 of

the Securities Exchange Act of 1934</div>

As of September 30, 2025

<div align='center'>TENARIS, S.A.

(Translation of Registrant's name into English)

26, Boulevard Royal, 4th floor

L-2449 Luxembourg

(Address of principal executive offices)

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

Form 20-F Form 40-F</div>

The attached material is being furnished to the Securities and Exchange
Commission pursuant to Rule 13a-16 and Form 6-K under the Securities Exchange Act of 1934, as amended. This report contains Tenaris’s
Weekly Report (September 29, 2025 – September 30, 2025) on the First Tranche of Tenaris Share Buyback Program.

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

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 30, 2025

<div align='center'>Tenaris, S.A.</div>

By: /s/ Giovanni Sardagna

Giovanni Sardagna

Investor Relations Officer

Giovanni Sardagna

Tenaris

1-888-300-5432

www.tenaris.com

Weekly Report (September 29, 2025 – September 30, 2025) on the First Tranche of Tenaris Share Buyback Program.

Luxembourg, September 30, 2025. - Tenaris S.A. (NYSE and Mexico:
TS and EXM Italy: TEN) (“Tenaris”) announced today that pursuant to its First Tranche of the USD1.2 billion Share Buyback
Program announced on June 6, 2025, covering up to USD600 million to be executed in the open market, it has repurchased the following ordinary
shares from September 29, 2025 to (and including) September 30, 2025:

From September 29, 2025 to (and