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

May 2018

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:

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 Extends Leadership Position in Shanghai Market with New Data Center Acquisition

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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.

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Exhibit 99.1

GDS Extends Leadership Position in Shanghai Market with New Data Center Acquisition

SHANGHAI, China, May 23, 2018 (GLOBE NEWSWIRE) — 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 the acquisition of a new data center in Shanghai (“SH11”). The data center is located close to the Company’s existing facilities in Waigaoqiao district, Shanghai’s premier data center hub. It is currently under construction and will enter service by mid-year. SH11 will provide around 4,000 sqm of high-density capacity, which is already 100% pre-committed by one of the Company’s leading Internet customers. The acquisition is expected to close in the current quarter.

“We are pleased to make another attractive acquisition which is consistent with our data center sourcing strategy,” stated Mr. William Huang, Chairman and Chief Executive Officer of GDS Holdings. “The acquisition will extend our leadership position in the Shanghai market where we now have over 50,000 sqm of data center capacity. It will quickly add to our supply, enabling us to fulfill more demand in hand from a major strategic customer. SH11 represents our fifth acquisition in the past two years. We will continue to pursue acquisitions of this type in tandem with our organic growth efforts. With dedicated sourcing teams in each Tier 1 market, this acquisition further demonstrates our ability to provide continuous resource supply to meet the expansion needs of our customers, setting us apart from others in the industry.”

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’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 customers to connect to all major PRC telecommunications carriers, and to access a number of the largest PRC cloud service providers, whom GDS hosts in its facilities. The Company offers colocation and managed services, including direct private connection to major cloud platforms. The Company has a 17-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 base of customers consists predominantly of hyper-scale cloud service providers, large internet companies, financial institutions, telecommunications and IT service providers, and large domestic private sector and multinational corporations.

Safe Harbor

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 outlook, 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 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 registration statement on Form F-1, as amended. 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) 2033-0295
Email: ir@gds-services.com

The Piacente Group, Inc.

Ross Warner 
Phone: +86 (10) 5730-6200 
Email: GDS@tpg-ir.com

Alan Wang 
Phone: +1 (212) 481-2050 ext. 401 
Email: GDS@tpg-ir.com