She represented South Korea in the global pop group Now United .

On November 15, 2017, Heyoon was revealed as part of the final lineup for global pop group Now United.

[4] In December of the same year, the group released their first single, "Summer in the City".

Heyoon states the release of the single to being one of her biggest highlights as a member of the group, as the song is entirely in Korean.

[8][9] On September 30, 2020, Now United released the music video for a song called "Somebody", where one of the clip's directors is Heyoon again.