Mohnish Bahl debuted with the film Bekarar in a supporting role opposite Padmini Kolhapure and co Starring Sanjay Dutt but the film was a critical and commercial failure. His subsequent release was Teri Bahon Mein, a remake of The Blue Lagoon with Ayesha Dutt wife of Jackie Sheroff, which was also a failure. His only commercial success in a leading role was Purana Mandir though it was considered a B grade film it was Maine Pyar Kiya in 1989, which transformed Bahl's career, and he later became known as a character actor. He has starred in over 100 films, and has been nominated for two Filmfare Awards.

Bahl was born in Mumbai, Maharashtra, India. He is the son of actress Nutan and Lt. Cdr. Rajnish Bahl, and is a prominent member of the Mukherjee-Samarth family. He is married to Ekta Sohini and they have two children.