Mallawarachchi debuted as a playback singer in the 1971 film, "Poojithayo". In 1984, he was honored with the best playback singer award at the Sarasawiya Awards for "Kendan Yannam," with Priya Suriyasena and Gration Ananda a song from Sena Samarasinghe's "Aethin Aethat". He was the main male playback singer in the movie "Senakeliya" which was a box office hit in 1974. Its songs included "Reyak Upadda" and duets with Indrani Perera on "Samanala Renak Se" and duets with Victor Ratnayake and CD Fonseka. The music director was Patrick Denipitiya.