The New Zealand Labour Party (Māori: Rōpū Reipa o Aotearoa), or simply Labour (Reipa), is a centre-left political party in New Zealand. The party's platform programme describes its founding principle as democratic socialism, while observers describe Labour as social-democratic and pragmatic in practice. The party participates in the international Progressive Alliance. It is one of two major political parties in New Zealand, alongside its traditional rival, the National Party.

The New Zealand Labour Party formed in 1916 out of various socialist parties and trade unions. It is the country's oldest political party still in existence. Alongside the National Party, Labour has alternated in leading governments of New Zealand since the 1930s. As of 2020, there have been six periods of Labour government under ten Labour prime ministers.

The party first came to power under prime ministers Michael Joseph Savage and Peter Fraser from 1935 to 1949, when it established New Zealand's welfare state. It governed from 1957 to 1960, and again from 1972 to 1975. In 1974, the prime minister Norman Kirk died in office, which contributed to a decline in party support. Up to the 1980s, the party advocated a strong role for governments in economic and social matters. When it governed from 1984 to 1990, Labour instead privatised state assets and reduced the role of the state in the economy; Labour prime minister David Lange also introduced New Zealand's nuclear-free policy. Labour again became the largest party from 1999 to 2008, when it governed in coalition with, or based on negotiated support from, several minor parties; Helen Clark became the first Labour prime minister to secure a third term in office.

In the 2017 general election the party, under Jacinda Ardern, returned to prominence with its best showing since the 2005 general election, winning 36.9% of the party vote and 46 seats. On 19 October 2017, Labour formed a minority coalition government with New Zealand First, with confidence and supply from the Green Party. In the 2020 general election, Labour won in a landslide, winning an overall majority of 10 and 50.01% of the vote. Jacinda Ardern currently serves as the party leader and prime minister, while Kelvin Davis is the deputy leader.