The Northern Ireland Assembly (Irish: Tionól Thuaisceart Éireann; Scots: Norlin Airlann Semmlie) is the parliament for the British part of Northern Ireland. It has wide-ranging legislative powers in areas not specifically reserved for the British Parliament. In addition, the Assembly elects the government of Northern Ireland. It is based in Belfast and meets in the Stormont district.

The current Parliament was created by the Good Friday Agreement of 1998, which was intended to end thirty years of conflict in Northern Ireland. It is based on the principle of concordance to ensure that Northern Ireland's two largest political groups, the Protestant Unionists and the Catholic Nationalists, participate in government. It is a unicameral parliament with 90 members. The election is by single transferable vote in the sense of proportional representation.

The Assembly has been suspended on a number of occasions, most recently from October 2002 until May 2007, during which time its powers were transferred to the Department of Northern Ireland. Under the St Andrews Agreement of November 2006, new elections were held in March 2007 and the Assembly's powers were restored.

Following a scandal over the Renewable Heat Incentive, the previous First Minister Martin McGuinness resigned as Deputy First Minister in early 2017, which, with his Sinn Féin party failing to provide a replacement, led to a new election in March 2017. However, as the Unionists (DUP) now no longer had an absolute majority in the Assembly, and they were unable to reach agreement with the opposition (Sinn Féin) on a number of issues (including same-sex marriage in Northern Ireland and an official language status in Northern Ireland for the Irish language), a new Executive could not be established, leaving the Assembly unable to act. The budget for Northern Ireland was passed as a substitute by the all-UK government in London in November 2017. Further talks between the DUP and Sinn Féin, with the support of Prime Minister Theresa May and Irish Taoiseach Leo Varadkar, have so far failed to produce any result, although the British and Irish governments promised to "intensify" negotiations in May 2019. On 21 October 2019, DUP and some SDLP MPs returned to the Assembly after 1008 days to symbolically debate a bill on the "protection of unborn life", but for procedural reasons the Assembly adjourned after less than an hour without passing a resolution.

The poor showing for both the DUP and Sinn Féin in the 2019 British House of Commons election was seen as a reaction from voters for years of political gridlock. New impetus for a fresh start came from the British government's offer to invest an additional £2 billion in the province's health system and infrastructure. Moreover, in January 2020, the Irish and British prime ministers came to the unanimous decision that the only way to resolve a continuing deadlock was to hold new elections in the near future. As a result of this, the leading Northern Ireland parties reached an agreement on 11 January 2020 to continue working in the regional parliament. Arlene Foster was reappointed as First Minister, with Michelle O'Neill as her deputy.