He went to M.G.P music academy to learn music under Ananda Perera's father. In 1968, he attended to the State Music College, now known as the Institute of Aesthetic Studies. Then he learned Western music under R.A. Chandrasena. At that time, he attended to the music classes conducted by
Premasiri Khemadasa. He started to play cello under the guidance of
M. K. Rocksamy and then from Miss Joyce at Ceylon Symphony. He became the only cello artist in the preceding years of 60s and 70s in every film. Rathnayake was the music director for many films directed by
Gamini Fonseka such as
Uthumaneni,
Sagarayak Meda,
Koti Waligaya and
Nomiyena Minisun. He composed the song
Paaradise sung by
H.R. Jothipala and Desmond Rodrigo. He made the lyrics for the song
Mihipita Bim Agalak sung by
W.D. Amaradeva for the film
Nomiyena Minisun. He was the music director for all the films directed by Dinesh Priyasad including,
Demodara Palama and
Peralikarayo. Then he continued to work in many blockbuster commercial films of
Roy de Silva such as
Re Daniel Dawal Migel film series,
Jonsun and Gonsun,
Cheriyo film series and
Sepata Dukata Sunny. He had to compose music for Hindi tunes in certain Sinhala films such as
Jaya Mangalam Suba Mangalam song sung by Jothipala for the film
Peralikarayo This song was the last film song written by
Karunaratne Abeysekera. Jothipala has sung to his music in many films such as
Ridee Thella,
Waradata Danduwam,
Paaradise and
Peralikarayo. He was also awarded the Sarasaviya Award for Best Music Director for the film
Ekada Wahi directed by Parakrama Jayasinghe. He also acted in that film. Rathnayake's maiden cinema acting came through the 1992 film
Raja Daruwo directed by
Daya Wimalaweera. For that film, he composed the popular song
Dilidune Daruwane Mage sung by
Gratien Ananda. He also composed music for several television serials such as
Sannaliyane and acted in the serial
Kiri Kandulak. Apart from that, Rathnayake also composed music for television cartoons. His song
Muhuda Mage Goda Bimai in the cartoon "Dosthara Honda Hitha" gained large popularity. He composed the most number of Christian songs as a Buddhist. ==Filmography==