Knut Joner is the son of actor Johannes Joner, and the grandson of actor Rolf Søder. Knut is also the cousin of the very well known actor Kristoffer Joner. Knut Joner had his actors debut in the lead of a children's TVseries on Norwegian television called "Arild and the invincible city" written by famous author Jostein Garder, aired on Norways main-channel, NRK in 1994. In 2008 he had a role in Unni Lindells "Nightsister" He starred in the play "Class Enemy" in 2006, it resulted in a movie called "Respekt" in 2008, directed by his father.