Ranjan, a 1993 batch IPS officer, has replaced G C Dwivedi with whom Delhi Chief Minister Arvind Kejriwal reportedly had differences on a number of issues including overall functioning of ACB.
Earlier this month, Kejriwal had requested Lt Governor Najeeb Jung to appoint Ranjan as head of ACB replacing Dwivedi.
Ranjan, an officer from Union Territory cadre, was heading the Economic Offences Wing (EOW) of Delhi Police.
"Recently, Kejriwal had urged Lt Governor Najeeb Jung to transfer top five Anti-Corruption Bureau officers including Additional Commissioner G C Dwivedi, one DCP and three DCPs. Ranjan's name was suggested by the government, which has been accepted," said the government source.