On March 31, 2017, Woollim had revealed the second unit for the W PROJECT. The unit was a rap unit that consisted of Jangjun and another member, TAG.
Later that year, Jang Jung was introduced as a member of Golden Child through the reality show 2017 Woollim Pick. He officially debuted with the group on August 28 with the release of their first mini album Gol-Cha! with "DamDaDi" as the title track.
On December 27, it was announced that the contracts of several Golden Child members with Woollim Entertainment will conclude on December 31. With only two members remaining with Woollim, including Jang Jun, the boy group effectively disbanded.[1]