Kim Hye-joon made her acting debut in the Naver web series Lily Fever in 2015. The following year, she became a regular cast member of the late-night program Saturday Night Live Korea. In 2019, she played one of the main characters in the Netflix zombie sageuk series Kingdom and reprised her role in its second season. Also in 2019, she starred in the drama film Another Child, which won her Best New Actress at the 40th Blue Dragon Film Awards. Her performance in the movie also earned her Best New Actress nominations at the 28th Buil Film Awards and the 56th Baeksang Arts Awards. In 2020, she acted alongside Oh Nara in the eight-episode MBC series United Effort to Accomplish One Thing, in which she was named Best New Actress at the MBC Drama Awards.
Kim Hye-joon majored in theater and film at Hanyang University.