THE9 was a nine member project girl group formed with the 2020 season of 青春有你 2 (Youth with You Season 2) under iQiyi. The show ran from March 12, to May 30, with the announcement of the official lineup.

The members, which consist of Baby Monster An, Kiki Xu, K, Esther Yu, Snow Kong, Shaking, Xiaotong Zhao, XIN Liu, and Yan Yu. Similar to other similar idol survival programs, many of the members are a part of other agencies, and some are currently or formerly part of other girl groups, with the exclusion of Esther Yu who primarily worked as an actress.

The group made their official debut with the single 斯芬克斯X谜 (Sphinx X) in August of 2020.

After a year of activities, the group would later disband on December 5th, 2021, THE9 with the release of their graduation EP THE NINE. In 2022, THE9’s graduation concert, 轨迹毕业演唱会由, held in Guangzhou, was temporarily canceled due to the pandemic, but was later held as a two day concert in October 27th and 28th, 2023, retitled《多远都可以到达》 in Nanjing.