Hong Su-ju began her career as a model. Prior to debuting as an actress in 2020, she appeared in several music videos such as Chanyeol’s “SSFW” and Henry Lau’s “I LUV U.” In 2021, she landed her first major acting role in the KBS Drama Special episode titled “Be;twin.” In 2023, she made a cameo in the second season of the Netflix apocalyptic horror series Sweet Home. She was later cast as one of the main characters in the 2024 Disney+ crime-suspense drama The Impossible Heir alongside Lee Jae-wook and Lee Jun-young.