Johnson is a prominent South Indian composer of film scores who has given music to some of the most important motion pictures of Malayalam cinema. He is noted for his lyrical and expressive melodies together with simple but rich tonal compositions of thematic music. Johnson was born in Thrissur, Kerala in South India to a Christian ("Nasrani") family. While young, he learned to play the violin and studied basic elements of European classical music. In his youth he was involved with a music group called 'Voice of Trichur', of which he was the music composer. The group used to perform music throughout Thrissur and neighbouring regions in Kerala. This brought him in contact with a music director of Malayalam cinema, G Devarajan. Devarajan offered him assignments in the film industry as an assistant music composer. Later, Johnson got his first major assignment as main composer for the film 'Aaravam' (1978).

He came to prominence through his collaboration with the great Malayalam director Padmarajan. This productive collaboration saw the detailed screenplay and cinematography of Padmarajan become a fertile ground for expressive musical narration and thematic scores for Johnson. This is seen in some of the greatest motion pictures of Malayalam cinema, like Namukku Parkkan Munthiri Thoppukal (1986), Oru minnaaminungintaey nurunguvettam (1987), Nombarathipoovu (1987) and Perumthachan (1990). He is also noted for his collaboration with the Malayalam lyricist Kaithapram Damodaran Namboothiri. Johnson is affectionately called as the 'John Williams' of Malayalam cinema, after the legendary Hollywood composer John Williams. Johnson won the Indian National award as Best Film Composer for two consecutive years. He won his first National Award in (1993) for the motion picture Ponthan Mada. The next year he got his second award for the film Sukrutham (1994). His skilful integration of textual rhythm of the lyrics together with rich tonal arrangement, redefined songwriting in Malayalam cinema, since the late 1980s. In his film scores, Johnson combines native South Indian melodic patterns with the harmonic structure of European classical music and this has attained an expressive form of narration through film score

List of major works Koodevide (1983) Kattathe Kilikoodu (1983) Namukku Parkkan Munthiri Thoppukal (1986) Oru minnaaminungintaey nurunguvettam (1987) Nombarathipoovu (1987) Aparan (1988) Artham (1989) Perumthachan (1990) Njan Gandharvan (1991) My Dear Muthachan (1992) Ponthan Mada (1993) Sukrutham (1994) Bhoothakkannadi (1997) Veendum Chila Veettukaryangal (1999) Yathrakarude Sradhakku (2002) Chenkol Savidham Oormakai Chamayam Kireedam Dasharatham Sasneham