London-born actor and singer, possibly best known on the screen as Private Hitch in Canlı Kafa Avcıları (1964), as Dr. Livesey in the musical version of Treasure Island (1982) and as the dapper lothario Steven Kodaly in BBC's adaptation of She Loves Me (1979) (based on the play 'Parfumerie' by Miklós László). He also had notable guest roles in two episodes of Tatlı sert (1961) and in the comedies Up Pompeii! (1969) and Çılgınlar Oteli (1972) .

Kernan's first acting experience was with the Huddersfield Repertory Company at the age of 19. In 1957, he appeared in the chorus line of 'Where's Charley' at London's Palace Theatre. This marked the beginning of a substantial career as a singer in stage musicals. Renowned as an expert interpreter of songs by Stephen Sondheim, he was acclaimed for his performance in the original 1977 Broadway cast of Sondheim's musical revue 'Side by Side', opposite Millicent Martin. A year earlier, he had headlined as Count Carl-Magnus Malcolm in 'A Little Night Music' at the Adelphi Theatre in London. From 1980 to 1981, he appeared in 'Kiss Me Kate' at the Bristol Old Vic and Theatre Royal.

Kernan also devised and directed the musical revue 'Jerome Kern Goes to Hollywood', which opened on Broadway in January 1986. During the 60s and 70s, he was a guest soloist in many British variety shows, performing songs by Sondheim, Cole Porter, Noël Coward, Irving Berlin, Johnny Mercer and Frank Loesser.

His 2019 autobiography is entitled 'From Eastham to Broadway'.