Jang Hyun-seung

In 2004, at the age of 15, Hyunseung took part in auditions for YG Entertainment. He was eliminated in the second round, but went to see CEO Yang Hyun-suk afterwards out of frustration at being eliminated and was accepted as a trainee.[11]

For a year and four months, Hyunseung was a trainee for the boy group Big Bang. During this time, he used the stage name "So-1," a homonym for the Korean word for wish. He first gained media attention when he appeared in the group's pre-debut "Big Bang Documentary," along with members G-Dragon, T.O.P, Taeyang, Daesung and Seungri. He appeared in 10 out of 11 episodes, but was cut from the group in a final elimination round with Seungri. Yang Hyun-suk said that Hyunseung's expressiveness and stage presence were underdeveloped at the time. Fellow Beast member, Yoon Doo-joon decided to become a singer after watching the Big Bang documentary featuring Hyunseung.[12] Hyunseung refers to his experiences at YG as important to his development as an artist.[11]

Hyunseung later met future fellow band member Yang Yo-seob while they were working as dancers for a show performance team. Yoseob convinced Hyunseung to join Cube Entertainment, leading to him debuting with Beast.[11]

The group has released 3 Korean albums, 9 Korean extended plays and various singles. In December 2010, Hyunseung teamed up with fellow member Lee Gi-kwang in a sub-unit to write and compose an R&B track as part of the group's digital album, My Story.

On May 7, 2015, Hyunseung released his solo debut extended play, My.[13] Other than BEAST's tracks, Hyunseung's album had more influences on hip-hop culture and pop culture in his preference, such as title track "Ma First" featuring Giriboy and "Break Up With Him" featuring Dok2.

In December 2011, Hyunseung formed a unit with label mate 4Minute's Hyuna called Trouble Maker. Trouble Maker debuted with their self-named lead single and extended play, Trouble Maker.[14] On October 28, 2013, the group released their second extended play, Chemistry.

Hyunseung made his acting debut in the musical Mozart!. He performed as the main character from late July 2012 to early August 2012 at the Sejong Center.[15]

In April 2014, Hyunseung was cast in the musical Bonnie & Clyde. He performed as the lead character, Clyde, from April 15 to June 29, 2014 at the BBC Art Center along with other artists, including SHINee‘s Key, ZE:A‘s Park Hyung Sik, Kahi, and Oh So Yeon.[16]

In April 2016, Hyunseung was nominated and won "Best Male Artist (South Korea)" at the 4th Annual V-Chart Music Awards in China.[17]

On April 19, 2016, Cube Entertainment announced he officially left Beast to continue as a soloist.[18][19]

On July 29, 2016, Cube Entertainment announced that Hyunseung would be joining the dance competition program Hit The Stage, making it his first broadcast appearance since leaving Beast.[20]

On December 13, 2016, it was confirmed that Hyunseung had renewed his exclusive contract with Cube Entertainment.[21]

On June 12, 2018, it was confirmed that Hyunseung will enlist in the military on July 24 as an active soldier.[22] He was discharged from the military on 13 March 2020.[23]