2017: GOOD DAY, The Unit
On July 9, 2017, she was announced as a member of C9 Entertainment's newest girl group GOOD DAY. They debuted on August 30, 2017, with their first mini album All Day Good Day.
Later that year, she became a contestant on KBS 2TV's reality survival show The Unit. She was eliminated in the episode 13 after ranking 24th place.
On November 14, 2019, Belle was introduced as a member of C9 Entertainment's next girl group, Cignature, which is now managed by the subsidiary J9 Entertainment.