Singh is specialist at handling anti-corruption operations and investigative work having earlier worked as a lead in the anti-corruption bureau for Rajasthan. He served the Indian Police Service for nearly four decades.
Ajit Singh will take charge ahead of the upcoming Indian Premier League beginning on April 7.
Neeraj Kumar, who recently investigated the Shami incident has been retained as an advisor until May 31.
Kumar wrote a letter to the Committee of Administrator and BCCI CEO Rahul Johri emphasising their disinterest in fighting corruption, and that could be the reason of the sudden removal of the man who kept Indian cricket corruption free since the spot-fixing scandal in the sixth edition of IPL.
Along with the International Cricket Council, the BCCI will work towards maintaining the highest level of compliance during the IPL.