The Prime Minister's Office (PMO) is an institution that functions as the administrative agency and staff arm of the Prime Minister of India. It is considered an extra-constitutional body as it is not explicitly mentioned in the Constitution of India. The PMO is politically headed by the Prime Minister and administratively led by the Principal Secretary to the Prime Minister.
The office originated in 1947 as the Prime Minister's Secretariat (PMS) under Jawaharlal Nehru. It was formally considered a part of the Indian government in 1961 when it was given the status of a department under the Allocation of Business Rules. The name was officially changed to the Prime Minister's Office (PMO) in June 1977 during the premiership of Morarji Desai.
The primary mechanism of the PMO is to provide secretarial assistance to the Prime Minister, helping him discharge his responsibilities as the chief executive. It manages all matters that must be handled by the Prime Minister according to the Rules of Business, acts as a think tank, and handles public relations. The PMO also manages the Prime Minister's National Relief Fund (PMNRF) and the National Defence Fund (NDF).
The PMO is closely connected to the Cabinet Secretariat and the National Security Council Secretariat, as these offices are housed in the same complex. The Prime Minister traditionally holds the portfolio for the Department of Atomic Energy (DAE) and the Department of Space (DoS), which are housed within the PMO.
A significant recent change occurred when the PMO relocated from the South Block of the Secretariat Building to a newly constructed complex under the Central Vista Redevelopment project. This new complex was renamed 'Seva Tirth' in December 2025, reflecting a philosophical shift towards service-centric governance.