Ganguly's grand father, the late Anil Basumallick, taught him chess at the age of 5. Soon he became very popular in chess circles of Kolkata as he was the youngest player in most tournaments taking place during those days and also won prizes. In 1991, at the age of 8, he won both the Indian National U-10 and U-12 Championships. He won these Championships again in 1992 and 1995.