The 1866 New Zealand general election was held between 12 February and 6 April to elect 70 MPs to the fourth term of the New Zealand Parliament.

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.