Born in Hyderabad, Mahendra attended Osmania University, where he took part in the Vandemataram strike.
In 1942, he joined the Communist Party of India (CPI), which encouraged him to become a trade unionist.
He went underground to participate in the Telangana Rebellion, and spent some time in prison in the early 1950s.
From 1996 until 2001, he served as general secretary of the All India Trade Union Congress.
He also served on the national executive of the CPI from 1997 until 2004, and from 2000 until 2005 was the president of the World Federation of Trade Unions.