Kwak Do-won began his acting career on stage before making his film debut in the 2003 comedy-drama film Ogu. This was followed by small roles in several films before finally taking the spotlight with his role as a public prosecutor in the 2012 movie Nameless Gangster: Rules of the Time. He was nominated for Best Supporting Actor at the 21st Buil Film Awards and the 33rd Blue Dragon Film Awards for his work in the film. That same year, he joined the main cast of the SBS series Ghost, which earned him acting trophies at the Korea Drama Awards and the SBS Drama Awards. In 2013, he starred in the courtroom drama film The Attorney, which scored him numerous Best Supporting Actor nominations and wins. In 2016, he acted alongside Hwang Jung-min and Chun Woo-hee in the horror film The Wailing by director Na Hong-jin. His performance in the movie won him the Daesang at the 37th Golden Cinema Festival as well as Best Actor in an International Film at the 2016 BloodGuts UK Horror Awards. In 2017, he appeared in the political drama film The Mayor, which gave him a Best Supporting Actor nomination at the 54th Grand Bell Awards.

Kwak Do-won previously dated actress Jang So-yeon, who he co-starred with in The Wailing. In 2018, an anonymous online post accused an actor with the initials “KDW” of repeated sexual harassment and physical assault against his co-workers. Though Kwak Do-won was not directly named, his agency firmly dismissed the accusations.