Sanu started his play back career with a Bangladeshi movie 'Tin Kanya' directed by Shibli Sadiq in 1986.This music, tin konyar ek chobi, was the title track of that movie.
In 1987, music director and singer Jagjit Singh offered Sanu the chance to sing in the Hindi film Aandhiyan. Sanu then relocated to Mumbai, where Kalyanji-Anandji gave him chance to sing in the film Jaadugar. Kalyanji-Anandji suggested that he change his name from Kedar Nath Bhattacharya to Kumar Sanu.
Sanu started off singing Jagjit Singh's film songs, and went on to work with composers including Naushad, Ravindra Jain, Hridayanath Mangeshkar, Pt.R K Razdan, Kalyanji Anandji, and Usha Khanna.
For the 1990 film Aashiqui, music directors Nadeem-Shravan got Sanu to sing all but one of the songs which included "Ek Sanam Chahiye", "Tu Meri Zindagi", "Nazar Ke Saamne", "Jaane Jigar Jaaneman", "Ab Tere Bin Jee Lenge Hum" and "Dheere Dheere Se". He won the first of his record five consecutive Filmfare awards as Best Male Playback Singer. His next Filmfare Awards came for songs in the movies Saajan (1991), Deewana (1992), Baazigar (1993), and 1942: A Love Story (1994).