[1] Rathnam was born at Malaiyappanallur near Kumbakonam in Tanjore District in the year 1897 to Narayana Padayatchi and Thangathammal.

His parents were agriculturists and Rathanm was acquainted with rural songs and folk arts from a very early age.

As a young boy, Rathnam learned to act from a stage actor named Parameswaran Iyer.

Following the success, Rathnam acted in hit movies such as Uthama Puthiran, Sathi Murali (1940), Sabapathy (1941), Manonmani (1943), Burma Rani (1945), Chow Chow (1945), Paranjothi (1945), Sri Murugan (1946), Arthanari (1946), Aaravalli (1946), Sahada Yogam (1946), Udayanan Vasavadatta (1947), Kannika (1947), Sulochana (1947), Sri Aandal (1948), Adhithan Kanavu (1948), Devdasi (1948), Pizhaikum Vali (1948), and Bhojan (1948).

[3][4] While in a drama tour of Coimbatore, Rathnam was impressed by the histrionic skills of C. T. Rajakantham, daughter of the owner of the house in which they stayed and inducted her into his troupe.