Choi Sung-won debuted as an actor in the 2010 musical While You Were Sleeping. He had appearances in several episodes of KBS Drama Special before rising to prominence for his role in the hit tvN series Answer Me 1988. He then played supporting characters in the JTBC sageuk Mirror of the Witch in 2016 and in tvN’s Smart Prison Living in 2017. In 2018, he became part of the KBS2 drama Miracle That We Met and JTBC’s My ID Is Gangnam Beauty. In 2019, he joined the main cast of the SBS series My Absolute Boyfriend. This was followed by a role in the 2019 tvN comic thriller Psychopath Diary. In 2022, he made his small screen comeback in the MBC supernatural mystery-comedy Showtime Begins!

Choi Sung-won was diagnosed with acute leukemia in May 2016. He was pronounced cancer-free in December of the same year. In November 2020, he once again underwent leukemia treatment following a relapse.