As a singer, Kumar's work with many music directors in this period includes "Ye Raatein Ye Mausam" and "Hum Toh Mohabbat Karega" from "Dilli Ka Thug", "Piya Piya Mora Jiya" from "Baap Re Baap", "Hello Hello Ji" from "Bombay Ka Chor", "Micheal Hai Toh Cycle Hai" from "Bewaqoof", "Ae Haseeno Nazneeno" from "Chacha Zindabad", "Zaroorat Hai Zaroorat Hai" from "Manmauji" (1961), "Likha Hai Teri Ankhon Mein" from "Teen Deviaan", "Suno Jaana Suno Jaana", "Pyaar Baatke Chalo" and "Kya Teri Zulfein Hai" from "Hum Sab Ustaad Hai", "Khoobsurat Haseena" from "Mr. X in Bombay", "Gaata Rahe Mera Dil" from "Guide" (1965), "Sultana Sultana" from "Shreeman Funtoosh", "Machalti Hui" from "Ganga Ki Lahren", "Mera Dil Meri Jaan" and "Pyar Ka Jaahan Hotel" from "Jaalsaaz" and "Yeh Dil Na Hota Bechara" from "Jewel Thief" (1967).