After acting in a couple of films in Calcutta, Mala Sinha went to Bombay for a Bengali film. There she met Geeta Bali, a noted Bollywood actress, who was charmed by her and introduced her to director Kidar Sharma. Sharma cast her as a heroine in his "Rangeen Ratein". Her first Hindi film was "Badshah" opposite Pradeep Kumar, then came "Ekadashi", a mythological film. Both films did not do well, but her lead role in Kishore Sahu's "Hamlet", paired opposite Pradeep Kumar, fetched her rave reviews in spite of it failing at the box office. Films such as "Lai Batti" (actor Balraj Sahni's only directorial venture), "Nausherwan-E-Adil" where she starred as the fair maiden Marcia in Sohrab Modi's romance about forbidden love and "Phir Subah Hogi", which was director Ramesh Saigal's adaptation of Dosteovsky's "Crime and Punishment" established Mala Sinha's reputation as a versatile actress who took the maximum career risks by accepting unconventional roles.