Jung Sung-il debuted as a theater actor in 2000. He then expanded to TV and film, making his first known big screen appearance in the 2002 movie H. He also played minor characters in The Art of Seduction in 2005 and in A Frozen Flower in 2008. In 2016, he landed a major role in the thriller film Unconfessional. In 2019, he became part of several TV series such as MBC’s Different Dreams and KBS2’s 9.9 Billion Won Woman. In 2020, he joined Forest of Secrets 2 and Birthcare Center, which both aired on tvN. In 2021, he acted alongside Lee Dong-wook in another tvN drama titled Bad and Crazy. In 2022, he starred with Song Hye-gyo in the Netflix original series The Glory.