The Principal Secretary to the Prime Minister of India is the administrative head of the Prime Minister's Office. The officeholder is generally a civil servant, commonly from the Indian Administrative Service and occasionally from the Indian Foreign Service.

The Prime Minister's Office (PMO) consists of the immediate staff of the Prime Minister of India, as well as multiple levels of support staff reporting to the Prime Minister. The PMO is headed by the Principal Secretary, currently Pramod Kumar Mishra. The PMO was originally called the Prime Minister's Secretariat until 1977, when it was renamed during the Morarji Desai ministry.