Singh, who was serving as Special Chief Secretary in the Panchayati Raj department, succeeded K Pradeep Chandra, who retrired from service yesterday.
Chandra held the post for a brief tenure of just one month.
In another appointment, A K Khan, who retired as Director General, ACB, has been made an adviser for Telangana State Minority Welfare, an official release issued here said.
The government also appointed Industries Secretary Arvind Kumar as Resident Commissioner of Telangana Bhavan in New Delhi.