The appointment of Kumar, a 1976-batch IPS officer, came barely a week before his birthday when he turns 59.
Gupta retires after remaining Delhi Police Commissioner since November 10, 2010.
He was also DG prisons when Anna started protest inside the Tihar Jail and is believed to have played a key role in resolving the deadlock between Team Anna and the government in getting him out of the jail.
He also led the investigations of serial blasts of Mumbai in 1993.
Besides, deportation of Aftab Ansari from Dubai in 2002. Ansari was the main accused in the shooting at the American Center in Kolkata.
Before taking over as the head of Tihar, Asia's largest prison, Kumar successfully handled security arrangement of the sporting mega event Commonwealth Games here in 2010 as Special Commissioner (Headquarters).
Kumar had started his stint in Delhi Police as ACP of Chanakyapuri in 1979.
He is a post-graduate from prestigious St Stephen's College, New Delhi.
He was also the brain behind exposing the alleged nexus between an Enforcement Directorate official and an arms dealer who were blackmailing a jeweller.
At Delhi Police, Kumar had also headed the special cell as Joint Commissioner.