ayanth began his film career with a small role in B. A. W. Jayamanne's Unmathu Wishwasaya (1952). His breakthrough came when he was cast in the lead male role on Sujatha (1953) opposite Florida Jayalath; it became a big hit and established Jayanth and Jayalath as major stars. They reappeared together in the 1955 film Seda Sulang which was also popular featuring the only songs sung by Lata Mangeshkar for a Sri Lankan film. Jayanth had a major role in Warada Kageda in 1953.
Jayanth subsequently acted in Awishwasaya, Purusha Rathnaya (1959) and Sithaka Mahima (1964) before reuniting with Jaylath in her directorial effort Sweep Ticket (1965). In 1967 he portrayed a role in Sarana. Jayanth married actress Nanda Leelanayake sometime in the 1960s and had seven children including Jagath Rohan who appeared in the film Sabeetha (1980).
Jayanth started his company Seven Arts around 1972 and produced such films as Sahanaya (1972), Hondata Hondai (1973), Kawda Raja (1976), Sabeetha (1980), Senasuma (1981) and Mala Giravi (1984). He was also active as a designer of film cutouts and was the art director of Wahal Doopatha (1968) and Deviyani Oba Kohida (1977).