The first minister and deputy first minister of Northern Ireland are the joint heads of government of Northern Ireland, leading the Northern Ireland Executive and with overall responsibility for the running of the Executive Office.

Despite the titles of the two offices, the two positions have the same governmental power, resulting in a diarchy; the deputy first minister is not subordinate to the first minister. Created under the terms of the 1998 Good Friday Agreement, both were initially nominated and appointed by members of the Northern Ireland Assembly on a joint ticket by a cross-community vote, under consociational principles. That process was changed following the 2006 St Andrews Agreement, such that the first minister now is nominated by the largest party overall, and the deputy first minister is nominated by the largest party from the next largest community block (understood to mean "Unionist", "Nationalist", or "Other").

On 17 June 2021, despite a letter from the Democratic Unionist Party chairman and other senior party members, DUP leader Edwin Poots nominated Paul Givan as First Minister and Sinn Féin re-nominated Michelle O'Neill as deputy First Minister. On 4 February 2022, Givan resigned as First Minister, which led to O'Neill automatically ceasing to hold office as deputy First Minister. The offices remained vacant until the appointment of O'Neill as First Minister, the first Irish nationalist to be appointed to the position, and DUP's Emma Little-Pengelly as deputy First Minister, on 3 February 2024.

The first minister and deputy first minister share equal responsibilities within government, and their decisions are made jointly. The first minister is, though, the first to greet official visitors to Northern Ireland and shares the same title as their counterparts in Scotland and Wales. Specifically, they are tasked with co-chairing meetings of the Northern Ireland Executive, "dealing with and co-ordinating" the work of the Executive, and the response of the administration to external relationships.

The first minister and deputy first minister agree the agenda of Executive meetings and can jointly determine "significant or controversial matters" to be considered by the Executive.

The ministers' policy responsibilities include:

Two junior ministers assist the first minister and deputy first minister in carrying out the work of Executive Office. They are jointly accountable to the first minister and deputy first minister. The incumbent junior ministers are Aisling Reilly (Sinn Féin) and Pam Cameron (Democratic Unionist Party).

As originally established under the Northern Ireland Act 1998, the first minister was elected by the Assembly on a joint ticket with the deputy first minister through a cross-community vote. It was created to enable the leaders of the main unionist and nationalist parties to work together, with guaranteed joint representation of both main communities. For the purposes of a cross-community vote, MLAs were designated as unionist, nationalist, or other.