Rajendra Kumar started his cinematic journey by serving as an assistant to director H. S. Rawail. He worked with him for almost five years and assisted him in his projects like Pocketmaar, Sagai, and Patanga. He made his acting debut with a brief role in Nargis and Dilip Kumar starrer film Jogan in the year 1950. Producer Narendra Goel was highly impressed by him and offered him a lead role in his film, Vachan which was released in 1955. He was paid just 1500 rupees for the film but the film was a silver jubilee hit and he was titled by media as 'A star is Born'.
It was the Oscar nominated Mehboob Khan’s film Mother India that catapulted him to the limelight and established him as one of the most sought after actors of Bollywood then. He was placed among the most sought after solo star after the release of Goonj Uthi Shehnai in 1959. After this film, Hindi cinema saw a phase of silver jubilee hit films by Rajendra Kumar like Saathi Mere Mehboob, Arzoo, Jhuk Gaya Aasman, Talaash among many others.
In most of the films in which he has acted, he portrayed the role of a patient and silent actor who sacrificed his love interest to others. In an illustrious acting career that he had, he was rarely seen shouting and jumping. In that time, he worked with almost all the leading actresses of the Bollywood. Among all his pairing with the actress, Sadhna was among the most noted one. Thrice in his career, he was nominated for Best Actor but unfortunately could never win that coveted trophy.