The appointment of Mr Kumar, a 1976-batch Indian Police Service (IPS) officer from Arunachal Pradesh, Goa, Mizoram and Union Territories (AGMU) cadre, comes barely a week before his birthday when he turns 59.
Reacting to his new assignment, Mr Kumar told Press Trust of India (PTI) that it was a matter of "a great honour and I will try hard to fulfill the expectations".
Mr Kumar, who has held various important posts during his career, including in the Central Bureau of Investigation (CBI), will take over as the Commissioner of Delhi Police on June 30.
The name of Mr Kumar was cleared by Union Home Minister P Chidambaram today, official sources said.
During his career spanning 36 years, Mr Kumar has worked on several important cases which include deportation of Aftab Ansari from Dubai in 2002. Ansari was the main accused in the shooting at the American Centre in Kolkata.
Before taking over as the head of Tihar, Asia's largest prison, Mr Kumar successfully handled security arrangement of the sporting mega event Commonwealth Games here in 2010 as Special Commissioner (Headquarters).
Mr Kumar had started his stint in Delhi Police as the Assistant Commissioner of Police (ACP) of Chanakyapuri in 1979.
A post graduate from prestigious St Stephen's College, the IPS officer had served in the Central Bureau of Investigation during which he probed Mumbai serial blasts.
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, Mr Kumar had also headed the special cell as Joint Commissioner.