The group consists of six members: Geonu, Bain, Lim Ji-min, Siwoo (formerly known as JM), DY, and Sangwoo.

[1][2][3] DY won first place and made his debut as the center of 1the9 while Bain was eliminated in the final episode.

[8] On June 30, Just B officially debuted with the release of their first extended play Just Burn and the lead single "Damage" was produced by Bang Yong-guk, a singer, rapper, songwriter and producer who was the leader of the boy group B.A.P.

[12] On February 14, 2023, Just B released their first collaboration project with soloist AleXa titled "MBTI".

[13] On April 12, 2023, Just B released their pre-release single "얼어있는 길거리에 잠시라도 따듯한 햇빛이 내리길" (Camelia) with lyrics penned by members DY and Sangwoo and composed by DY.