6-K

United States

Securities and Exchange Commission

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer

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

of the

Securities Exchange Act of 1934

For the month of

June 2026

Vale S.A.

Praia de Botafogo nº 186, 18º andar, Botafogo

22250-145 Rio de Janeiro, RJ, 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.)

(Check One) Form 20-F x Form 40-F ¨

Vale releasesits Sustainability-Related Financial Information Report Rio de Janeiro, June 15, 2026 – Vale S.A. (“Vale” or the “Company”)announces today, on a voluntary basis, the release of its 2025 Sustainability-Related Financial Information Report, reinforcing the company’spioneering role on sustainability and transparency. Vale was the first mining company in the world and the first Brazilian company topublish, last year, a report aligned with the new standards established by the International Sustainability Standards Board (ISSB) forreporting sustainability-related risks and opportunities. In its first edition, the report focused on climate-related data. In this secondedition, Vale expands its risk analysis to four additional topics: tailings dams, environmental licensing, community relations and humanrights, and health and safety. It also introduces a new business opportunity linked to waste reuse. “This second edition of theISSB-aligned report reflects the evolution and maturity of Vale’s sustainability agenda. We have advanced in integrating sustainabilityand finance, providing increasingly consistent and relevant information to support responsible investment decision-making. This reinforcesour commitment to transparency, the quality of disclosed data, and long-term sustainable value creation”, said Grazielle Parenti,Executive Vice President of Sustainability. The new opportunity identified is circular mining, a term used to describe the applicationof circular economy principles to mining. The goal is to maximize the use of extracted resources, including the reuse of process waste,to reduce waste and environmental impacts while creating business value. Last year, Vale produced 26 million tonnes of iron ore throughcircularity initiatives, an increase of 107% compared to the previous year. Currently, circular mining accounts for 8% of the company’stotal production, with an ambition to reach 10% of total production by 2030. Key initiatives under the Circular Mining Program includethe reuse of materials from stockpiles and tailings dams, as well as the production of co-products such as Sustainable Sand and constructioninputs derived from iron ore processing waste. Other business opportunities highlighted in the report include growing demand for ironore products that can help reduce carbon emissions in the steel industry, as well as increasing demand for energy transition metals suchas copper and nickel. The publication of the ISSB-aligned report reflects Vale’s commitment to transparency, which includes disclosingrelevant documents to support investor decision-making, such as the Annual Report released in April. “By publishing reports basedon globally recognized standards, we disclose our sustainable practices transparently, supporting responsible investment decisions andenhancing the quality and reliability of ESG-related information. Transparency is a key pillar of Vale’s relationship with investorsand society”, said Marcelo Bacci, Executive Vice President of Finance and Investor Relations. Vale’s ISSB-aligned reportwas prepared in accordance with the IFRS Sustainability Disclosure Standards, ensuring a high level of transparency regarding the financialimpacts of the company’s sustainability initiatives. Marcelo Feriozzi Bacci Executive Vice President, Finance and Investor RelationsFor further information, please contact: Press Release [email protected] Thiago Lofiego: [email protected] Luciana Oliveti: [email protected] Terra: [email protected] Patricia Tinoco: [email protected] This press release may include statements that present Vale’sexpectations about future events or results. All statements, when based upon expectations about the future, involve various risks anduncertainties. Vale cannot guarantee that such statements will prove correct. These risks and uncertainties include factors related tothe following: (a) the countries where we operate, especially Brazil and Canada; (b) the global economy; (c) the capital markets; (d)the mining and metals prices and their dependence on global industrial production, which is cyclical by nature; and (e) global competitionin the markets in which Vale operates. To obtain further information on factors that may lead to results different from those forecastby Vale, please consult the reports Vale files with the U.S. Securities and Exchange Commission (SEC), the Brazilian Comissãode Valores Mobiliários (CVM) and in particular the factors discussed under “Forward-Looking Statements” and “RiskFactors” in Vale’s annual report on Form 20-F. ****

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.