DPMC was formed as a result of a report that recommended establishing structures to provide two separate streams of advice to the Prime Minister.
These streams were a new government department to supply impartial, high quality advice and support to the Prime Minister and Cabinet (DPMC); and a Prime Minister's Private Office (which is not part of DPMC), to provide personal support and media services, and advice of a party political nature.
DPMC was established on 1 January 1990. Government House was included in the scope of the department in August 1990, after a review of the Governor-General’s support requirements. The External Assessments Bureau (now called the National Assessments Bureau) became part of DPMC on 1 July 1991.
The Ministry of Civil Defence and Emergency Management became a business unit within DPMC in April 2014.
The Canterbury Earthquake Recovery Authority (CERA) became a departmental agency within DPMC in February 2015. On 1 March 2016, to coincide with the wind down of CERA, a new business group - the Greater Christchurch Group - was formed to focus on the ongoing regeneration of Christchurch and support the transition of leadership from central government to local institutions. CERA was disestablished on 18 April 2016.