Prior to his involvement with YG Entertainment, Seunghyun was an underground rapper under the name of Tempo, and a childhood friend of G-Dragon, another member of Big Bang. G-Dragon stated that the two were “neighborhood friends from middle school” and would often dance and rap together. Although G-Dragon later moved away and the two “became distant”, he contacted Seunghyun again when YG Entertainment was scouting for candidates to create a boy band. The pair recorded several demos and sent them to Yang Hyun Suk, CEO of YG Entertainment, who later asked Seunghyun to audition. Seunghyun was initially rejected by the record label, which deemed him too “chubby” to fit the “idealistic version” of an idol. Seunghyun later stated that he “went home and exercised really hard because I wanted to join YG Entertainment.” Six months later, he returned for another audition and was signed on. He reportedly lost 20 kg in 40 days.
Choi Seung Hyun was given the stage name of T.O.P. by fellow YG artist Se7en. He became one of the two rappers in the group Big Bang, alongside G-Dragon. In 2011, T.O.P. and bandmate, G-Dragon collaborated to record and release the album GD & TOP Volume 1. He has also branched out to act in various dramas and films, including I Am Sam, Iris, Nineteen and 71: Into the Fire.