Sh. Raj Kumar Singh is a former Indian bureaucrat and presently Cabinet Minister (Power, New & Renewable Energy) in the Government of India. Sh. R. K. Singh is a native of Supaul district in Bihar and a Member of Indian Parliament since May 2014. 

Sh. R K Singh is a 1975 batch Bihar cadre Indian Administrative Service officer and a former Home Secretary, Govt. of Bihar. He was District Magistrate in East Champaran and Patna in 1980s before joining State Home Department in 1997. As a Joint Secretary in the Ministry of Home Affairs from 2000- 2005, he revamped the Scheme for Police Modernization and started the Scheme for Prison Modernization. During 2006–2009, he served as the Principal Secretary in road construction department, Govt. of Bihar and played an important role in improving the conditions of roads in Bihar.