He was born Abhas Kumar Ganguly in Khandwa. At the age of 18, he came to Bombay where elder brother Ashok Kumar was a major star. He got his first opportunity as a singer in Bombay Talkies Ziddi (1948) where he sang the song Marne ki Duayen Kyon Mangu for Dev Anand. Being an ardent admirer of KL Saigal, the song was sung in the style of the legend. But in spite of Ziddi's success, Kishore found few offers forthcoming and did the odd singing assignment with bit roles making a rather tepid acting debut as hero in the forgettable Andolan (1951).
Kishore was initially taken quite lightly as a singer and was given mainly lighter songs by Burmanda and other music directors. But with his soulful rendering of Dukhi Man Mere from Funtoosh (1956), Kishore was now taken seriously as a singer. Though he was formally untrained, he assimilated jazz-scat fragmented musical notes into a rhythmic sequence and once its beat was established, departed from the pattern and combined notes and words/ syllables into new kinds of musical harmony. And none could yodel better than he could!