The New Zealand Government is the central government through which political authority is exercised in New Zealand. As in most other parliamentary democracies, the term "Government" refers chiefly to the executive branch, and more specifically to the collective ministry directing the executive. Based on the principle of responsible government, it operates within the framework that "the [King] reigns, but the government rules, so long as it has the support of the House of Representatives". The Cabinet Manual describes the main laws, rules and conventions affecting the conduct and operation of the Government.

The New Zealand Parliament is the unicameral legislature of New Zealand, consisting of the Sovereign (King-in-Parliament) and the New Zealand House of Representatives. The King is usually represented by his governor-general. Before 1951, there was an upper chamber, the New Zealand Legislative Council. The New Zealand Parliament was established in 1854 and is one of the oldest continuously functioning legislatures in the world. It has met in Wellington, the capital of New Zealand, since 1865.