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

June 2020

Commission File Number: 001-37925

GDS Holdings Limited

(Registrant’s name)

2/F, Tower 2, Youyou Century Place

428 South Yanggao Road

Pudong, Shanghai 200127

People’s Republic of China

(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 x       Form 40-F o

Indicate by check mark if the registrant is submitting the Form 6-K on paper as permitted by Regulation S-T Rule 101(b)(1): o

Indicate by check mark if the registrant is submitting the Form 6-K on paper as permitted by Regulation S-T Rule 101(b)(7): o

EXHIBITS

Exhibit 99.1 — Press release — GDS Announces Equity Investment by Hillhouse and STT GDC

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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.

3

Exhibit 99.1

GDS Announces Equity Investment by Hillhouse and STT GDC

Shanghai, China, June 22, 2020 — GDS Holdings Limited (“GDS Holdings”, “GDS” or the “Company”) (NASDAQ: GDS), a leading developer and operator of high-performance data centers in China, today announced that two long-term investors, Hillhouse Capital (“Hillhouse”) and ST Telemedia Global Data Centres (“STT GDC”), have agreed to purchase, through a private placement, a total of $505 million of newly issued Class A ordinary shares of the Company at a price equivalent to $65 per ADS. The private placement represents approximately 5.1% of the Company’s total outstanding shares. Hillhouse will subscribe $400 million and STT GDC will subscribe $105 million. The purchase price reflects a 5.9% discount to the VWAP (volume weighted average price) of GDS shares for the last 10 trading days ended June 19, 2020.

Following the equity investment, Hillhouse’s ownership position in GDS will be approximately 3.9% and STT GDC will be approximately 34.2%. The proceeds from the investment will be used by GDS for its organic data center development, potential acquisition opportunities, and other general corporate purposes.

The transaction is expected to close in the next few days. It is expected that the share issuance will be exempted from registration under the Securities Act of 1933, as amended, (the “Securities Act”) pursuant to Section 4(a)(2) of the Securities Act regarding transactions not involving a public offering or Regulation S under the Securities Act.

“I am very pleased to secure this capital to support our growth at a time when new IT infrastructure development in China is going to a higher level,” said Mr. William Huang, Chairman and Chief Executive Officer of GDS. “Furthermore, I am very pleased to have done it in a way which adds value to GDS and strengthens our shareholder base. Hillhouse is one of the most respected investors, and we look forward to working with them over the long term. I also very much appreciate the on-going support from our strategic partner, STT GDC.”

About GDS Holdings Limited

GDS Holdings Limited (Nasdaq: GDS) is a leading developer and operator of high-performance data centers in China. The Company’s facilities are strategically located in China’s primary economic hubs where demand for high-performance data center services is concentrated. The Company also builds-to-suit and operates data centers at lower-tier locations selected by its customers in order to fulfill their broader requirements. The Company’s data centers have large net floor area, high power capacity, density and efficiency, and multiple redundancy across all critical systems. GDS is carrier and cloud-neutral, which enables its customers to access all the major PRC telecommunications networks, as well as the largest PRC and global public clouds which are hosted in many of its facilities. The Company offers colocation and managed services, including direct private connection to leading public clouds, an innovative service platform for managing hybrid clouds and, where required, the resale of public cloud services. The Company has a 19-year track record of service delivery, successfully fulfilling the requirements of some of the largest and most demanding customers for outsourced data center services in China. The Company’s customer base consists predominantly of hyperscale cloud service providers, large internet companies, financial institutions, telecommunications carriers and IT service providers, and large domestic private sector and multinational corporations.

Safe Harbor Statement

This announcement contains forward-looking statements. These statements are made under the “safe harbor” provisions of the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified by terminology such as “aim,” “anticipate,” “believe,” “continue,” “estimate,” “expect,” “future,” “guidance,” “intend,” “is/are likely to,” “may,” “ongoing,” “plan,” “potential,” “target,” “will,” and similar statements. Among other things, statements that are not historical facts, including statements about GDS Holdings’ beliefs and expectations regarding the growth of its businesses and its revenue for the full fiscal year, the business outlook and quotations from management in this announcement, as well as GDS Holdings’ strategic and operational plans, are or contain forward-looking statements. GDS Holdings may also make written or oral forward-looking statements in its periodic reports to the U.S. Securities and Exchange Commission (the “SEC”) on Forms 20-F and 6-K, in its annual report to shareholders, in press releases and other written materials and in oral statements made by its officers, directors or employees to third parties. Forward-looking statements involve inherent risks and uncertainties. A number of factors could cause GDS Holdings’ actual results or financial performance to differ materially from those contained in any forward-looking statement, including but not limited to the following: GDS Holdings’ goals and strategies; GDS Holdings’ future business development, financial condition and results of operations; the expected growth of the market for high-performance data centers, data center solutions and related services in China; GDS Holdings’ expectations regarding demand for and market acceptance of its high-performance data centers, data center solutions and related services; GDS Holdings’ expectations regarding building, strengthening and maintaining its relationships with new and existing customers; the continued adoption of cloud computing and cloud service providers in China; risks and uncertainties associated with increased investments in GDS Holdings’ business and new data center initiatives; risks and uncertainties associated with strategic acquisitions and investments; GDS Holdings’ ability to maintain or grow its revenue or business; fluctuations in GDS Holdings’ operating results; changes in laws, regulations and regulatory environment that affect GDS Holdings’ business operations; competition in GDS Holdings’ industry in China; security breaches; power outages; and fluctuations in general economic and business conditions in China and globally, the impact of COVID-19 outbreak, and assumptions underlying or related to any of the foregoing. Further information regarding these and other risks, uncertainties or factors is included in the GDS Holdings’ filings with the SEC, including its annual report on form 20-F. All information provided in this press release is as of the date of this press release and are based on assumptions that GDS Holdings believes to be reasonable as of such date, and GDS Holdings does not undertake any obligation to update any forward-looking statement, except as required under applicable law.

For investor and media inquiries, please contact:

GDS Holdings Limited

Laura Chen

Phone: +86 (21) 5118-6915

Email: ir@gds-services.com

The Piacente Group, Inc.

Ross Warner

Phone: +86 (10) 6508-0677

Email: GDS@tpg-ir.com

Brandi Piacente

Phone: +1 (212) 481-2050

Email: GDS@tpg-ir.com

GDS Holdings Limited