Raj Kumar Singh (born 20 December 1952) is a former Indian bureaucrat and former Union Cabinet Minister in the Government of India (2014 - 2024).

Singh is a 1975 batch Bihar cadre Indian Administrative Service officer and former Home Secretary of India.

For this Mr. Singh was empowered through a special order by the then Chief Minister Lalu Prasad Yadav and sent on deputation to Samastipur as Additional Magistrate.

[9][10][11][12][13] In 2013, Singh was tipped to be adviser (infrastructure) in the Nitish Kumar-led Bihar government, a post created through cabinet approval.

[15][16] Singh was chosen by the then Union Home Minister P. Chidambaram for his efficiency and no-nonsense attitude.

However, Singh had several run-ins with Chidambaram's successor, Sushilkumar Shinde, who was not happy with the home secretary's handling of the situation following 16 December 2012 Delhi gang rape.

[27][28] He contested the election as a BJP candidate in Arrah, beating his nearest rival, Sribhagwan Singh Kushwaha of RJD by a margin of over 1,35,000 votes.

[34] In the 2024 Indian general election he lost his MP seat from Arrah, Bihar to Communist Party of India (Marxist–Leninist) Liberation candidate Sudama Prasad by the margin of 59808 votes.