Since his acting debut in 1977, Kim has had a long career on the stage, in television dramas and film.

[1] Kim Kap-soo gained recognition for his outstanding performance in the 1984 play "The Silence of the Master," which portrayed the life of Han Yong-un (Monk Manhae).

Kim dedicatedly portrayed the role of Han Yong-un for three consecutive months at the Seoul Sesil Theater.

In 2000, in the KBS1 drama Taejo Wang Geon, Kim Gap-soo shines as a loyal royal scribe, showcasing his talent and establishing himself as a standout in the series.

[3] He, who is also the head of the theater company 'Actors' World', took time between his appearances in movies and dramas to perform the charity play 'Tongbuk-eo' for the underprivileged in 10 cities across the country, including Incheon, Gwacheon, and Pyeongchang, at the end of 2008.