Mohanlal Viswanathan was born in the village of Elanthoor in the Pathanamthitta district on 21 May 1960. He is the youngest child of Viswanathan Nair, a former bureaucrat and law secretary with the Kerala Government, and Santhakumari. He grew up at Mudavanmugal, Poojappura, at his paternal house in Thiruvananthapuram. Mohanlal studied at Government Model Boys Higher Secondary School, Thiruvananthapuram and graduated with a Bachelor of Commerce degree from Mahatma Gandhi College in Thiruvananthapuram.

Mohanlal had acted in several amateur plays before entering into films. In 2001, he debuted in professional drama playing Karna (a character from the Indian epic Mahabharata) in Karnabharam, a Sanskrit-language play directed by Kavalam Narayana Panicker. It premiered at the Siri Fort Auditorium in New Delhi on 29 March 2001 as part of the National Theatre Festival of the National School of Drama. The play depicts Karna's mental agony a day before the Kurukshetra War, as he thinks about his past and his faith. Mohanlal said: "You cannot compare Kavalam's play with the amateur plays I did. Though there are other characters in the play, the theme revolves around Karna. It is almost like a solo performance. Some of the scenes are really touching and challenging". He acted without payment, saying: "I performed for the joy of it ... for my love of our history". Kadhayattam was a presentation enacted by Mohanlal, performing ten classic characters and situations from Malayalam literature, selected from ten Malayalam novels written by O. Chandu Menon, C. V. Raman Pillai, S. K. Pottekkatt, Thakazhi Sivasankara Pillai, P. Kesavadev, Vaikom Muhammad Basheer, Uroob, O. V. Vijayan, M. Mukundan, and M. T. Vasudevan Nair over a 100-year period. The play, directed by T. K. Rajeev Kumar premiered at the Senate Hall of University of Kerala on 1 November 2003, and later was staged in Kozhikode, Bangalore, Chennai and Delhi. In 2008, Mohanlal along with Mukesh performed in Chayamukhi, written and directed by Prasanth Narayanan. Mohanlal and Mukesh portrayed Bheeman and Keechakan respectively, the characters from Mahabharata. It had a play within a play narrative style. It premiered at the Lulu International Convention Centre in Thrissur on 12 March 2008, and later was staged in Thiruvananthapuram, Bangalore, Kollam, Kochi, and Kozhikode. A critic from The Hindu wrote: "Chayamukhi is, arguably, the finest work on Malayalam stage in recent times". In the same year, Mohanlal voiced Hanuman in the English ballet Maya Ravan, directed by Shobana. In 2014, Mohanlal and musician Ratheesh Vegha formed the music band Lalisom - The Lal Effect. Its maiden show was at the 2015 National Games of India. The band drew flak from social media initially for charging an amount of Rs1.63 crore and later for lip-syncing. Following the criticism, Mohanlal returned the amount to the government, which they refused stating that the government's morality would not allow to take back the money and Mohanlal had not personally benefited from the amount which he received, since it was meant to meet the stage expenses and remuneration for the artistes. Despite that, Mohanlal did not take back the money he dispatched. In 2015, he collaborated once again with Mukesh for Naga, but this time as the narrator. The play, based on Girish Karnad's Kannada play Nagamandala, was directed by Suveeran. Naga was a combination of myth, superstition, fact, and fantasy. It was premiered at the Parish Hall of St. George Church, Kalady on 9 August 2015.

did he have a partner?
he collaborated once again with Mukesh for Naga,