He had a long standing passion to be an actor star where he frequently went to the film halls to watch English and Sinhala films. A relative called Punya Bulathsinhala referred him to the director of the film Hadawath Naththo Subayar Makeem in 1974. Karunaratne made his maiden cinematic appearance through the 1974 film Hadawath Naththo as a stuntman. The first scenario was the fight with Robin Fernando at the Rubber Estate. He went missing from the films for about a year after Hadawath Naththo. After that, with the help of Karunadasa Perera, the then production manager of the films, Karu re-entered the film industry by joining the fight scenes in films such as Yakadaya, Hitha Mithura, Sankapali and Saradielge Putha directed by Neil Rupasinghe and Sarath Rupasinghe.
With that he acted in more than 250 Sinhala films and 15 television serials particularly as the villain. Apart from cinema, he appeared in the television serials Thara Devi produced by Lucien Bulathsinhala and also in the serials Eranga and Ran Kahawanu. Meanwhile, he also worked as the stunt director in few films. In 2018 he appeared in the music video Danuna produced by Iraj Weeraratne, where the public later criticized his appearance for the life of popular singer Victor Rathnayake. 2b1af7f3a8