The commercially successful films of Kumar included "Ladki" (1953), "Naukari" (1954), "Baap Re Baap" (1955), "Paisa Hi Paisa" (1956), "New Delhi" (1956), "Naya Andaz" (1956), "Bhagam Bhaag" (1956)"," "Bhai Bhai" (1956), "Aasha" (1957), "Chalti Ka Naam Gaadi" (1958), "Dilli Ka Thug" (1958), "Jaalsaaz (1959)", "Bombay Ka Chor (1962)", "Chacha Zindabad (1959)", "Man-Mauji" (1962), "Jhumroo" (1961), "Half Ticket" (1962), "Mr. X in Bombay (1964)", "Shreeman Funtoosh" (1965), "Ek Raaz (1963)", "Ganga Ki Lahren (1964)", "Hum Sab Ustaad Hai" (1965), "Haal E Dil", "Pyar Kiye Jaa (1966)", and "Padosan" (1968). As an actor, his best period was between 1954 and 1966. His onscreen pairing with actresses Mala Sinha, Vyjayanthimala, Nutan, Madhubala and Kumkum gave the biggest hits in his career.