Jeon Do Yum, known professionally as DY, is a South Korean singer, dancer, former member of 1THE9 (원더나인) and current member of JUST B (저스트비). He graduated from Hanlim Entertainment Arts High School.

Before debuting, he was a trainee at C9 Entertainment and appeared in "Under Nineteen" and finished in 1st place, earning a spot in the project group.

He made his debut in April 2019 as 1THE9's main dancer, lead rapper, vocalist and center with their first mini-album, "XIX". They were supposed to be active for around one year, so in August 2020, MBK Entertainment (MBK 엔터테인먼트, formerly known as PocketDol Studio) announced their disbandment.

After switching agencies, he signed with Bluedot Entertainment (블루닷엔터테인먼트) and re-debuted in June 2021 as part of JUST B with their first mini-album, "Just Burn".

In September 2024, JUST B joined ATBO and formed a special project group called THE CREW ONE (더크루원) in order to participate in the survival show "Road to Kingdom Season 2".

In April 2025, he complained of abdominal pain during JUST B's performance in Los Angeles, and he was taken to a hospital. He was diagnosed with appendicitis and underwent surgery. He spent one month focusing on his health before re-joining the group, but with limited physical activities.

(Source: MyDramaList) Edit Biography