Born in a poor Brahmin family in Kasaragod, Umanath learnt to play harmonium to accompany his mother who eked out a livelihood as a Bhajan singer.

While his family had hoped that Umanath, a student of Annamalai University, would land in a good job, he disappointed them by quitting his studies to become a full-time member of the Communist party.

[2] He joined the Communist Party of India in 1939 while studying at the Annamalai University in Tamil Nadu.

Umanath was arrested along with P. Ramamurthi in 1940 in connection with the Madras Conspiracy Case, and jailed for three years.

He served as one of the Vice Presidents of the Centre of Indian Trade Unions till 2010.