Mahanta was born in a xattriya family to Harendranath Mahanta and Lakhmipriya Devi in Hemabori area Nagaon district in 1942.
As a child, he heard his mother sing various songs like aainaam, borgeet and biyanaam. Those songs formed the very basis of the musician in him.
In Class III Mahanta charmed the school inspector singing Aji moja petuwa pet bhorai kha, a song written by Mitradev Mahanta.
Gradually the musician in him grew, making him the most sought after Bihu performer on stage in Assam. He learnt to play the tabla and learnt classical music from Sushil Banerjee in Nagaon. Mahanta completed his schooling from St Edmunds College, Shillong and graduated from Gauhati University.
In Shillong, he became associated with cultural organisation Shillong Kalakendra with which he toured the country. Mahanta and other music lovers met regularly. Cultural icon Bishnu Prasad Rabha taught them music. He also met Rudra Barua, another prominent name in Assamese music industry.
In 1956, when his elder sister was married to lyricist Keshab Mahanta, he came in contact with another icon.
During Bhaxa Andolon (1960), eminent persons like Bishnu Prasad Rabha, Gonoxilpi Hemanga Biswas and sculptor Jugal Das formed a movement to restore peace and harmony. Mahanta joined it. In 1961, Mahanta performed songs in front of thousands in Calcutta along with dhol expert Moghai Oja.
Mahanta had a stint in acting, too, after Chandra Phukan brought him to the stage. In 1961, he acted in Assamese film Xokuntola, directed by Bhupen Hazarika.
He lent his voice for the first time to an Assamese film when Abdul Majid directed Morom Trishna. His songs were aired on All India Radio for the first time in 1961.
Three years later, he got recognition from AIR as a regular singer. The same year he joined AIR and retired from there as deputy director in 2001. Songs like Dhonsiri pare hoi dhopoliyai ahilo and Poka tul tul bilahi that he sang in the sixties are still hummed by people.
In 1973, Mahanta married singer Archana Das and since then the couple entertained people with numerous stage performances. In 1992, he was bestowed with the Sangeet Natak Akademi award.