Within a few years, the club became one of the most sought after musical troupes in Kerala, and had more than fifty members. This club used to give accompaniment music to playback singers Jayachandran and Madhuri in their musical shows. It was Jayachandran who introduced Johnson to G. Devarajan, one of the most prolific composers of South Indian cinema then. Devarajan literally adopted Johnson and brought him to Chennai in 1974. Johnson bought an accordion, during this period, from R. K. Shekhar (A. R. Rahman's father), and began assisting Devarajan in filmscoring and composing. Johnson began his independent career by composing the film scores of Bharathan's "Aaravam" (1978), "Thakara" (1980) and "Chamaram" (1980). He composed his first soundtracks for the film "Inaye Thedi", debut film of director turned still photographer Antony Eastman and actress Silk Smitha. It was Devarajan himself, who suggested Johnson to the director. Then came Bharathan's "Parvathi" and Balachandra Menon's "Premageethangal". "Premageethangal" was a notable success with four of its songs – "Swapnam Verumoru Swapnam", "Nee Nirayoo Jeevanil", "Muthum Mudipponnum" and "Kalakalamozhi" attaining cult status. He came to prominence through his collaboration with Malayalam author and director Padmarajan. "Koodevide" was their first venture, which had one of the most famous songs of Johnson "Aadivaa Kaatte", a pathbreaking song in Malayalam music history. It was one of the first songs in Malayalam to so many western classical elements. The song was born out of Padmarajan's need for a western song for his innovative film. Song composition took place in Woodland's Hotel, Chennai. Another notable feature of this song was the lyrics by O. N. V. Kurup, who for the first time wrote lyrics for a pre-composed song. Johnson worked for 11 films with Padmarajan, including his last film "Njan Gandharvan". 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 "Nombarathipoovu" (1987).