He is the son of actress Nutan and Rajnish Bahl. He comes from a prominent film family. His great grandmother was Rattan Bai, his grandmother was Shobana Samarth, his maternal aunt is actress Tanuja and his cousin is popular actress Kajol who is married to actor Ajay Devgan. (see Mukherjee-Samarth family (film)) Mohnish is married and has a daughter. Mohnish Behl made his first impact playing the villain in Maine Pyar Kiya. He is probably known for playing villainous roles in his movies, notably the spoilt brat "Bali" in Shola Aur Shabnam, as "Narendra" in the hit film Deewana and the manipulative son in law "Rajesh" in Ek Rishtaa: The Bond of Love. He has done many films in which he plays the "good guy". His most memorable role was in Hum Aapke Hain Kaun as the elder loveable brother of Salman Khan. He has a critically acclaimed hit with Astitva where he played a music teacher. He has recently ventured into television and stars in the hit show Devi.