[3] He won the 2009 and 2019 Indian general election from Valmiki Nagar constituency being a Janata Dal (United) candidate.

[6][7] Baidyanath Prasad Mahto was Branch Manager, in National Co-operative Bank, Bettiah (Bihar) in the years 1992-95 and after that he resigned from bank manager post and became active in party politics.

He also fought and lost MLA election in 1995 as Samata Party candidate and finished with second position from Nautan.

After that he contested elections again in 2000 as Samata Party candidate and won from Nautan (Vidhan Sabha constituency).

[8] Following the death of Baidyanath Prasad Mahto without completing his term as Member of Parliament, his son Sunil Kumar won the By-election conducted to fill the vacancy on Valmikinagar seat in 2020 on Janata Dal (United) ticket.