Hariharan was born to Tamil parents, he grew up in Mumbai and has bachelor's degrees in science and law. He did his collegiate studies from S.I.E.S. College. The son of renowned Carnatic vocalists, Shrimati Alamelu and the late H.A.S. Mani, he inherited his parents' musical talents. He was also exposed to Hindustani music from a young age. In his teens, inspired by the songs of Mehdi Hassan , Hariharan developed a passion for ghazals and started training in Hindustani music from Ustad Ghulam Mustafa Khan. At the start of his career, Hariharan did the concert circuit and also performed on TV. His debut song "Ajeeb Sa neha Mujh Par Guzar gaya yaaron" in Hindi movie Gaman. He entered the world of Tamil films in 1992 introduced by debutant music director A.R. Rahman with the patriotic song "Thamizha Thamizha" in Maniratnam's film Roja. Hariharan has been one of the most trusted singers of Rahman and has sung many songs for him in long list of movies that includes Muthu, Minsara Kanavu, Jeans, Indian, Mudhalvan, Taal, Rangeela, Indira, Iruvar, Anbe Aaruyire, Kangalal Kaithu Sei, Sivaji, Alaipayuthey, Kannathil Muthamittal, Guru, Enthiran etc. He has sung more than 500 Tamil songs and nearly 200 Hindi songs. He has also sung hundreds of songs in Malayalam, Telugu, Kannada, Marathi and Bengali languages. He is one of the foremost Indian ghazal singers and composers with more than thirty albums to his credit. One of Hariharan's first ghazal albums was Aabshar-e-Ghazal with Asha Bhosle, which went gold in sales.Another outstanding ghazal album was Gulfam, which hit double platinum in sales. The album Lahore Ke Rang Hari Ke Sang with renowned ghazal composers from Pakistan won him rave reviews and critical acclaim inside and outside India. Their first album, Colonial Cousins was a fusion album and was the first Indian act to be featured on MTV Unplugged. The 2009 Tamil film Modhi Vilayadu had score and soundtrack composed by Colonial Cousins. They also scored the 2010 Tamil film Chikku Bukku. He also performed the Swagatham song in the 2010 Commonwealth Games opening ceremony held in New Delhi on 3 October.