Choi Sung-eun began acting in short student films and on stage. In 2019, she bagged her first major role in a feature film in the comedy-drama movie Start-Up, which won her Best New Actress at the 25th Chunsa Film Arts Awards. In 2020, she landed her first TV acting gig in an episode of MBC’s sci-fi anthology series SF8. In 2021, she acted alongside Shin Ha-kyun and Yeo Jin-gu in JTBC’s Beyond Evil, which was selected as Best Drama at the 57th Baeksang Arts Awards. Her work in the series also scored her a Baeksang Best New Actress nomination. That same year, she led the film Ten Months.

Choi Sung-eun graduated from Kaywon High School of Arts and then continued her studies at Korea National University of Arts’ acting department.