New Zealand First, commonly abbreviated to NZ First or NZF, is a right-wing populist political party in New Zealand, founded and led by Winston Peters, who has served three times as deputy prime minister. The party has formed coalition governments with both major political parties in New Zealand: with the New Zealand National Party from 1996 to 1998 and 2023 to present, and with the New Zealand Labour Party from 2005 to 2008 and 2017 to 2020. New Zealand First currently serves in a coalition government with both National and ACT New Zealand as part of the Sixth National government, having won 6.08% of the total party vote in the 2023 New Zealand general election.

New Zealand First was formed shortly before the 1993 New Zealand general election, following the resignation of Winston Peters as the National Party MP for Tauranga after criticising the party's neoliberal economic policies. The party gained support from National Party and Labour voters alike disenchanted with the support of both parties for extensive deregulation. New Zealand First entered the New Zealand House of Representatives shortly after its formation. The party had 17 members of parliament (MPs) at its peak, following the 1996 New Zealand general election, the first to use mixed-member proportional representation. That election the party swept the Māori seats, leading to the "Tight Five" of New Zealand First MPs from those electorates. The party had gained considerable support among socially conservative Māori voters, an association still visible today. By the end of their first term, however, the New Zealand First caucus had fallen to 9 MPs due to internal conflict over the coalition government with the National Party.

After agreeing a confidence and supply with Labour in 2005, the party left parliament following the 2008 New Zealand general election in which it failed to gain enough party votes to retain seats. However, in the 2011 New Zealand general election, New Zealand First gained 6.59% of the total party vote, entitling it to eight MPs. The party increased its number of MPs to eleven at the 2014 New Zealand general election. During the 2017 election, the party's number of MPs dropped to nine members. In the weeks following the 2017 election, New Zealand First formed a coalition government with the Labour Party. In the 2020 election New Zealand First's share of the party vote fell to 2.6%, with all incumbent MPs, including Peters, losing their seats in Parliament. The party returned to parliament in 2023.

New Zealand First distinguishes itself from the mainstream political establishment through its use of populist rhetoric, and supports binding referendums on major social and political issues.

In June 1992, Winston Peters, a former Minister of Māori Affairs in the National Party government of Jim Bolger, was told that he would not be allowed to run for another term as National Party Member of Parliament for Tauranga in the 1993 election. Peters had previously been dismissed from the Cabinet in 1991, after he publicly criticised National's economic policy, colloquially dubbed Ruthanasia. Spearheaded by Minister of Finance Ruth Richardson, National arguably had gone beyond the extensive deregulation started by the New Zealand Labour Party in the 1980s, enacting widespread austerity and slashing benefits in the Mother of All Budgets of 1991. The budget cut spending on many of the welfare state institutions established in the 1930s by the First Labour Government. The unemployment benefit was cut by $14.00 a week, sickness benefit by $27.04, families benefit by $25.00 to $27.00 and universal payments for family benefits were completely abolished. After the death of protectionist former Prime Minister Robert Muldoon – who resigned from his Tamaki constituency in protest – Peters became Ruthanasia's leading opponents, and National's most prominent dissenter.

By late 1991, the National Party had become the most unpopular governing party since the Great Depression, with one poll result putting them as low as 22%. After his sacking, Peters decided to capitalise on National's unpopularity. On 19 March 1993, Peters resigned from the National Party. He also resigned from Parliament, triggering a by-election in his electorate on 17 April 1993 in which he stood as an independent, winning with 90.8% of votes due to neither Labour nor National running a candidate. On 18 July 1993, shortly before the writs were issued for that year's general election, Peters formed New Zealand First as a political grouping. At the time of its formation, New Zealand First's policy platform was broadly conservative and reactionary in that it opposed both Labour and National, the major centre-left and centre-right parties respectively. Peters claimed to be reviving National policies from which the Bolger government had departed.

Variably dubbed a social conservative, economic nationalist, or right-wing populist, Peters' rise was fueled by the enormous financial changes New Zealand underwent during the 1980s and 90s, during which time the economy was thoroughly deregulated by both the Labour Party and the National Party. A fierce opponent of both neoliberalism and progressivism, Peters gained support from both National Party and Labour voters disenchanted with the support of both parties for economic liberalisation. As Peters was a Māori conservative, he gained strong support particularly from socially conservative Māori voters who had voted Labour consistently until they began enforcing neoliberal policies, colloquially called Rogernomics. The party was soon widely regarded as having a distinct Māori character or even being "pro-Māori".

In the April 1993 special by-election, Tauranga voters re-elected Peters as an independent. At the general election six months later, New Zealand First received 8.4% of the total vote. Peters easily retained Tauranga, and Tau Henare, another New Zealand First candidate, won the Northern Māori seat, giving the party a total of two MPs. This did much to counter the perception of New Zealand First as merely a personality-driven vehicle for Peters.