Jang Keun-Suk made his acting debut in the 1997 HBS sitcom “Selling Happiness” (Haengbokeul Pabmoda). He then continued to work in television as a child actor. In middle school, Geun-Suk heard the music of Japanese pop singer Ken Hirai & Japanese rock band L’Arc-en-Ciel. He was inspired enough by these bands to start learning Japanese by himself. In junior high school, Keun-Suk went to school in New Zealand to learn English and Japanese. Because of his studies in New Zealand, he can carry casual conversations in both languages. Even though Keun-Suk wanted to continue his studies in New Zealand, a job offer brought him back to South Korea, a role in the popular MBC sitcom Nonstop 4. After his work in Nonstop 4, Keun-Suk fell into a self-perceived slump and didn’t think his acting was good enough. He decided then to re-devote himself to becoming a true actor. In 2005, Geun Seok’s portrayal of the president’s son in the SBS drama “Lovers In Prague” became a hit and was well regarded by drama fans.
In 2006, Keun-Suk made the jump to the big screen in the Japanese horror film One Missed Call Final where he played the role of a deaf boy. Using his past experience with the Japanese language, Keun-Suk was able to communicate with his Japanese co-stars with ease. He also learned sign language in preparation for his role.
Back on the small screen, he next played the role of Kim Eun-ho, Hwang Jin-yi's first love in the TV drama Hwang Jin-i. Geun-Suk’s performance gained the attention of many female fans. He also starred in the KBS drama, Hong Gil Dong, as Prince Lee Changhwi. In 2007, Geun-Suk was cast in the rock music themed film “The Happy Life.” His portrayal of Hyeon-ju in “The Happy Life” allowed Keun-Suk to show off his masculine charms, as well as display his skills as a singer. Geun-Suk would go on to play in two more music inspired titles in 2008, with the feature film Do Re Mi Fa So La Ti Do and the hit MBC TV drama Beethoven Virus.
Keun-Suk’s next role in the 2009 thriller The Case of Itaewon Homicide was his first villain role. The film is based on a true story of a murder that occurred at a Burger King restaurant in Itaewon, South Korea. Geun-Suk portrayed the role of Pearson, a disturbed, young Korean-American accused of stabbing a student to death. Keun-Suk had to speak his lines in English throughout the film, a job he did well, according to BeyondHollywood.com: “Jang Keun Suk performs very well as the sullen Pearson.”