[21Vianet Group, Inc. Announces Receipt of Preliminary Non-Binding “Going Private” Proposal BEIJING, China, June 10, 2015 — 21Vianet Group, Inc. (Nasdaq: VNET) (“21Vianet” or the “Company”), a leading carrier-neutral internet data center services provider in China, announced that its Board of Directors (the “Board”) has received a non-binding proposal letter, dated June 10, 2015, from Mr. Josh Sheng Chen (“Mr.] [FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ 21Vianet Group, Inc. Shang-Wen Hsiao Chief Financial Officer 6-K 1 d941588d6k.htm FORM 6-K]

[21Vianet Group Inc. Announces Change in Leadership Team BEIJING, June 10, 2015 – 21Vianet Group, Inc. (NASDAQ:VNET) (“21Vianet” or the “Company”), a leading carrier-neutral internet data center services provider in China, today announced that Mr. Frank Meng, the president of the Company, will be leaving the Company to pursue other opportunities, effective immediately. Mr. Josh Chen, Founder, Chairman and Chief] [FORM 6-K 21Vianet Group, Inc. M5, 1 Jiuxianqiao East Road, Chaoyang District Beijing 100016 The People’s Republic of China (86 10) 8456 2121 x ¨ Form 20-F ¨ ¨ 21Vianet Group, Inc. Shang-Wen Hsiao Chief Financial Officer 6-K 1 d941584d6k.htm FORM 6-K]