As a student activist, he left his graduate college to join the ‘Quit India Movement’. For his participation in the Indian independence movement, he spent 26 months in prison.
After India gained independence, Thakur worked as a teacher in his village’s school. He became a member of the Bihar Vidhan Sabha in 1952. He served as the Chief Minister of Bihar from December 1970 to June 1971 and from December 1977 to April 1979.
He was popularly known as ‘Jan Nayak’. A socialist leader, Karpoori Thakur was close to Jaya Prakash Narayan. He died on 17 February 1988. His birthplace, Pitaunjhia, was renamed to ‘Karpoori Gram’ after his death.
Karpoori Thakur served as the President of ‘Sanyukta Socialist Party’. He is called a mentor to the prominent Bihari leaders. He will always be known as the champion of the cause of the Dalits and the poor. He introduced reservation for the backward classes in the Government jobs, in 1978.