Choi Su-jong debuted in the 1987 KBS soap opera Love Tree. In 1998, he was cast in the KBS melodrama Legendary Ambition, which won him the Daesang at the 1998 KBS Drama Awards and the Best Actor for TV at the 35th Baeksang Arts Awards. He also gained various acting recognitions for his work in several sageuk dramas. In 2001, he took home another Daesang at the KBS Drama Awards for his portrayal of the title role of King Taejo in Taejo Wang Geon. In 2005, Choi Su-jong received a Top Excellence Award at the KBS Drama Awards for his role as Jang Bogo in Emperor of the Sea. In 2007, he earned yet another Daesang at the KBS Drama Awards for his portrayal of the title character in Dae Jo-yeong. In 2018, he starred in the KBS2 family drama My Only Ally, which won him a Top Excellence Award at the 2018 KBS Drama Awards and the Daesang at the 12th Korea Drama Awards.
Choi Su-jong married actress Ha Hee-ra in 1993. They have two children: a son born in 1999 and a daughter born in 2000. Choi Su-jong and Ha Hee-ra are known for being active in charitable projects. In 2009, they were selected as ambassadors for a worldwide campaign against tuberculosis and also as goodwill ambassadors for the National Museum of Korea. The couple is also known for their happy marriage. In a 2020 TV guesting, Choi Su-jong revealed that he has never been in a fight with his wife.