Basu was born in New Delhi, India, into a Bengali family. She is the second of three daughters to her parents, the elder being Bidisha, and the younger—Vijayeta. Although she was born in New Delhi, her family later moved to Kolkata.

According to her, she had come into modelling and acting quite by accident, because initially she had planned to study medicine.^[2] Basu studied science till the 12th standard at Bhavan's Gangabux Kanoria Vidyamandir and later took up commerce at The Bhawanipur Gujarati Education Society College, an undergraduate college affiliated with the University of Calcutta. In Kolkata, she did modelling and rampshows partime. Although, as pointed above, she intended to become a doctor, her aversion for dissections made her opt for chartered accountancy.^[3] However, in 1996, she met well-known model Mehr Jessia in Kolkata; the latter suggested that Basu take part in the Godrej Cinthol Supermodel contest. She eventually participated, and won the contest