Kim Eui-sung made his acting debut in 1988 with a small role in director Jang Sun-woo’s classic film The Age of Success. He then became active performing on stage before returning to the big screen in 1995 with Mother Has a Lover. In 1996, he starred in Hong Sang-soo’s directorial debut titled The Day a Pig Fell Into the Well. In 2011, he reunited with Hong in the drama film The Day He Arrives. In 2012, he played a supporting role in the box-office hit Introduction to Architecture. In 2013, he appeared in the film The Face Reader, which was named Best Film at the 50th Grand Bell Awards. His performance in the movie also scored him a Baeksang Best Supporting Actor nomination. In 2016, he acted alongside Gong Yoo in the blockbuster zombie film Train to Busan, which earned him Best Supporting Actor trophies at the 25th Buil Film Awards and the 53rd Baeksang Arts Awards. That same year, he became part of the MBC series W–Two Worlds, which gave him a Golden Acting Award at the MBC Drama Awards. In 2021, he joined the main cast of SBS’s Taxi Driver, which won him Best Supporting Actor at the SBS Drama Awards.

Kim Eui-sung attended the Seoul National University.