On September 16, the sixth video of the Rookie Station was released, featuring members Johnny, Yuta, Ten, and Jaehyun.

On March 6, a clip of Hansol, Johnny, Taeyong, Yuta, Ten, and Jaehyun (as SR15B) dancing to the song "Bassbot" was released.

On July 9, 2015, members Koeun, Hina, and Herin were introduced as they were to become "Mouseketeers" on Disney Channel Korea's The Mickey Mouse Club alongside Mark, Jeno, Donghyuck, Jaemin, Jisung, and Lami.

On July 30, a video of Hansol, Johnny, Taeyong, Yuta, Ten, and Jaehyun (as SR15B) performing a dance routine was released.

On December 22, Lami, Hina, and fellow trainee Park Jungyeon made appearances in video teasers for Winter Garden 2015.

SM Entertainment founder Lee Soo-man announced a concept for a new boy band, to be called NCT, in which different teams would debut based in different countries around the world.

Jungwoo and Koeun made appearances in the music video of Super Junior member Yesung's single "Paper Umbrella" later that month.

After almost a one-year absence, member Kun appeared with Lucas and Jungwoo for the opening SM Rookies' Instagram account.

In late June, Herin was confirmed as a contestant of Mnet's survival show Idol School, leading to her departure from the team and SM Entertainment.

[12] On February 14, NCT U released the single "Boss", recorded by Lucas and Jungwoo alongside members Taeyong, Doyoung, Jaehyun, Winwin, and Mark.

[15] On October 1, Yiyang confirmed she had left SM Entertainment and returned to China to join the idol competition show The Next Top Bang.

On December 31, SM Entertainment announced the debut of Hendery, Xiaojun and Yangyang as members of NCT's Chinese sub-unit, WayV.

Shohei was not added to the lineup due to personal health reasons, with the company planning to support his individual activities in the future.

[26][27][28] On May 31, 2023, Eunseok and Seunghan announced they had graduated from the team through handwritten letters posted on the SM Rookies's Instagram.

[33][34] On September 27, Yushi and Sion announced they had graduated from the team through handwritten letters posted on the SM Rookies's Instagram.