Ramanath Rai was born 8 March 1952 to Bellipady Perne Narayan Rai and Girija Rai. He entered politics when he became a member of the Indian National Congress. He has represented the Bantwal constituency of the Karnataka Legislative Assembly since 1985 until he lost it to his cousin B. Nagaraja Shetty in 2004. He however won the same constituency in 2008. In his long career as a legislator in the Karnataka Assembly he has served as minister holding various portfolios.
He also won 2013 Assembly election from Bantwal. He has been given the portfolio of Minister for Forest, Environment and Ecology.