Hariharan was also exposed to Hindustani music from a young age. In his teens, inspired by the songs of Mehdi Hassan and Jagjit Singh, Hariharan developed a passion for ghazals and started training in Hindustani music from Ustad Ghulam Mustafa Khan. He used to put in thirteen hours of singing practice everyday.
In 2004, he was honoured with the Padma Shri by the Government of India and is a two-time National Award winner. Hariharan, associating with Leslie Lewis, formed Colonial Cousins, a two-member band. They have cut many private music albums and also scored music for few feature films in Tamil cinema and Bollywood cinema.