# List of New Zealand by-elections

By-elections in New Zealand occur to fill vacant seats in the House of Representatives. The death, resignation, or expulsion of a sitting electorate MP can cause a by-election. (Note that list MPs do not have geographic districts for the purpose of provoking by-elections – if a list MP's seat becomes vacant, the next person on his or her party's list fills the position.) Historically, by-elections were often caused by general elections being declared void.

## Background

Under the Electoral Act 1993, a by-election need not take place if a general election will occur within six months of an electorate seat becoming vacant, although confirmation by a resolution supported by at least 75% of MPs is required. In 1996 the general election date was brought forward slightly, to 12 October, to avoid a by-election after the resignation of Michael Laws. Twice, in 1943 and 1969, by-elections were avoided after the deaths in election years of Paraire Karaka Paikea and Ralph Hanan by passing special acts, the By-election Postponement Act 1943 and the By-election Postponement Act 1969.
In recent years by-elections have not occurred particularly frequently – only one in the 2002–2005 parliamentary term, and none in the 1999–2002 or 2005–2008 terms. This is because most MPs who retire mid-term (e.g. Labour MPs Jim Sutton and Michael Cullen) were List MPs, so are simply replaced by the next member below them on their party list (unless that person is already an electorate MP, or does not agree). Some MPs have entered Parliament when two or more people above them on the list have declined, sometimes after pressure from their party: in 2008 Dail Jones (New Zealand First) and Russel Norman (Green); and in 2011 Louisa Wall (Labour) after five above her on the list declined.
Historically, however, they have taken place considerably more frequently – the 2nd Parliament of 1856–1860, for example, saw 33 by-elections and four supplementary elections, despite the House of Representatives originally having just 37 seats (increasing to 41 seats during the parliamentary term).
In the past it was not uncommon for an MP who died in office to be replaced with an immediate family member such as a brother, wife (see widow's succession), or son. This resulted in the election of the first woman MP Elizabeth McCombs (who was in turn succeeded by her son Terry McCombs), the first woman National MP Mary Grigg, and the first woman Māori MP Iriaka Rātana; all of whom took over their husband's seat. This practice has however fallen out of favour since the mid-seventies with the election of John Kirk to his late father's seat being the last occasion this happened at a by-election.
Mary Grigg was elected unopposed, and Wood notes that the 1942 Mid-Canterbury by-election is an extreme case where the election was gazetted without date of election, and four different dates are available from reputable sources: Official Year-book, Parliamentary Record, Journals of the House and J Boston.
Twelve Prime Ministers first came to parliament via by-elections: Julius Vogel, Harry Atkinson, Robert Stout, John Ballance, William Hall-Jones, William Massey, Peter Fraser, Keith Holyoake, Walter Nash, Bill Rowling, David Lange and Geoffrey Palmer. Six Prime Ministers (William Fox, Henry Sewell, Edward Stafford, George Grey, Joseph Ward and Jacinda Ardern) have won by-elections later in their parliamentary careers, while Labour leaders Harry Holland and David Shearer were also first elected via a by-election.
Some minor party founders have also launched their parties by resigning from a major party and their seat, then contesting it for their new party. Party founders who have done this include Matiu Rata and Tariana Turia. Both resigned from Labour to form Māori parties. In 1980 Rata was unsuccessful in retaking his Northern Maori electorate for his newly formed Mana Motuhake party, but in 2004 Turia successfully reclaimed Te Tai Hauauru for the Māori Party. In addition, Winston Peters resigned from National and his parliamentary seat in 1993, retaking the seat as an independent and going on to form the New Zealand First party. In these circumstances, by-elections are seen as a legitimisation of the MP's rejection of his or her old party. In addition, they provide vital publicity and something of a mandate for the new party.
By-elections for the party in government in the two-party era due to a resignation were sometimes an opportunity for party supporters to abstain or to vote against the government if they disapprove of their party's policies, without endangering the government. Bruce Beetham entered parliament for Social Credit at the 1978 Rangitikei by-election, as did Gary Knapp in the 1980 East Coast Bays by-election. In the 1994 Selwyn by-election National retained the seat, but the Alliance candidate came second, perhaps held by votes from disaffected Labour voters for the Alliance candidate. The 1926 Eden by-election was won by Labour who became the official opposition, helped by a split over the Reform candidate selection.

## Pre-party era

| By-election and electorate | By-election and electorate | Date | Incumbent | Reason | Winner |
| 1st Parliament (1853–1855) ||||||
| 1854 | Town of Nelson | 19 June | William Travers | Resignation | Samuel Stephens |
| 1854 | Waimea | 21 June | William Cautley | Resignation | William Travers |
| 1854 | City of Auckland | 4 August | Thomas Bartley | Resignation | William Brown |
| 2nd Parliament (1855–1860) ||||||
| 1856 | Motueka and Massacre Bay | 19 May | Charles Parker | Resignation | Herbert Curtis |
| 1856 | Christchurch Country | 14 October | Dingley Brittin | Resignation | John Ollivier |
| 1856 | Grey and Bell | 14 October | Charles Brown | Resignation | John Lewthwaite |
| 1856 | Town of Christchurch | 18 November | Henry Sewell | Resignation | Richard Packer |
| 1856 | Hutt | 27 November | Alfred Ludlam | Resignation | Samuel Revans |
| 1858 | City of Auckland | 27 April | John Logan Campbell | Resignation | Thomas Forsaith |
| 1858 | Pensioner Settlements | 29 April | Joseph Greenwood | Resignation | Jermyn Symonds |
| 1858 | Southern Division | 8 May | Charles Taylor | Resignation | Theodore Haultain |
| 1858 | Grey and Bell | 17 May | John Lewthwaite | Resignation | Charles Brown |
| 1858 | Waimea | 21 May | Charles Elliott | Resignation | David Monro |
| 1858 | Wairau | 21 May | William Wells | Resignation | Frederick Weld |
| 1858 | Town of Lyttelton | 28 May | James FitzGerald | Resignation | Crosbie Ward |
| 1858 | Akaroa | 31 May | John Cuff | Resignation | William Moorhouse |
| 1858 | Dunedin Country | 16 June | John Cargill | Resignation | John Taylor |
| 1858 | Wairarapa and Hawke's Bay | 22 July | J. Valentine Smith | Resignation | James Ferguson |
| 1858 | City of Wellington | 27 July | Isaac Featherston William Fitzherbert | Resignations | Isaac Featherston William Rhodes |
| 1858 | Wellington Country | 29 July | Dudley Ward | Resignation | Alfred Brandon |
| 1858 | Hutt | 31 July | Dillon Bell Samuel Revans | Resignations | Alfred Renall William Fitzherbert |
| 1859 | Town of Dunedin | 14 January | James Macandrew | Resignation | James Macandrew |
| Supplementary election, 1859 ||||||
| Cheviot | Cheviot | 18 December | 18 December | 18 December | Edward Jollie |
| Marsden | Marsden | 29 November | 29 November | 29 November | James Farmer |
| Wairarapa | Wairarapa | 7 November | 7 November | 7 November | Charles Carter |
| Wallace | Wallace | 30 November | 30 November | 30 November | Dillon Bell |
| By-election | Electorate | Date | Incumbent | Reason | Winner |
| 2nd Parliament (continued) ||||||
| 1859 | Waimea | 26 December | William Travers | Resignation | Fedor Kelling |
| 1860 | Town of Christchurch | 18 January | Richard Packer | Resignation | Henry Sewell |
| 1860 (1st) | Suburbs of Auckland | 25 January | Walter Brodie | Resignation | Theophilus Heale |
| 1860 | Dunedin Country | 28 March | William Cargill | Resignation | Thomas Gillies |
| 1860 (1st) | Christchurch Country | 2 April | John Ollivier | Resignation | Isaac Cookson |
| 1860 | City of Auckland | 5 April | Thomas Beckham | Resignation | Archibald Clark |
| 1860 (2nd) | Suburbs of Auckland | 5 April | Frederick Merriman | Resignation | Joseph Hargreaves |
| 1860 | Omata | 16 April | Alfred East | Resignation | James Richmond |
| 1860 (2nd) | Christchurch Country | 21 April | John Hall | Resignation | Charles Hunter Brown |
| 1860 | County of Hawke | 26 April | James Ferguson | Resignation | Thomas Fitzgerald |
| 1860 | Northern Division | 23 May | Thomas Henderson | Resignation | Thomas Henderson |
| 1860 | Grey and Bell | 28 May | Charles Brown | Resignation | Thomas King |
| 1860 (3rd) | Suburbs of Auckland | 4 August | Joseph Hargreaves | Resignation | John Logan Campbell |
| 3rd Parliament (1861–1865) ||||||
| 1861 | Grey and Bell | 20 June | William King | Death | Harry Atkinson |
| 1861 | Suburbs of Nelson | 20 June | James Wemyss | Resignation | William Wells |
| 1861 | Napier | 1 July | Henry Stark | Resignation | William Colenso |
| 1861 | Wanganui | 5 July | Henry Harrison | Resignation | Henry Harrison |
| 1862 (1st) | City of Dunedin | 17 March | Thomas Dick | Resignation | Thomas Dick |
| 1862 | Town of New Plymouth | 5 May | William Richmond | Resignation | Isaac Watt |
| 1862 (2nd) | City of Dunedin | 30 May | Edward McGlashan | Resignation | John Richardson |
| 1862 | Ellesmere | 9 June | Thomas Rowley | Resignation | James FitzGerald |
| 1862 | Avon | 11 June | Alfred Creyke | Resignation | William Thomson |
| 1862 | Heathcote | 12 June | George Hall | Resignation | William Moorhouse |
| 1862 | City of Auckland West | 14 June | Josiah Firth | Resignation | James Williamson |
| 1862 | Bruce | 31 July | Charles Kettle | Death | Edward Cargill |
| 1862 (3rd) | City of Dunedin | 15 November | John Richardson | Resignation | James Paterson |
| 1862 | Hampden | 4 December | Thomas Fraser | Absence | John Jones |
| Supplementary election, 1863 ||||||
| Dunedin and Suburbs North | Dunedin and Suburbs North | 28 March 1863 | 28 March 1863 | 28 March 1863 | John Richardson |
| Dunedin and Suburbs South | Dunedin and Suburbs South | 6 April 1863 | 6 April 1863 | 6 April 1863 | William Reynolds |
| Gold Fields | Gold Fields | 14 April 1863 | 14 April 1863 | 14 April 1863 | William Baldwin George Brodie |
| By-election | Electorate | Date | Incumbent | Reason | Winner |
| 3rd Parliament (continued) ||||||
| 1863 | Dunedin and Suburbs South | 20 June | James Paterson | Resignation | James Paterson |
| 1863 | Hampden | 2 July | John Jones | Resignation | Frederick Wayne |
| 1863 | Kaiapoi | 2 September | Isaac Cookson | Resignation | Robert Wilkin |
| 1863 | Dunedin and Suburbs North | 3 September | Thomas Dick | Resignation | Julius Vogel |
| 1863 | Town of New Plymouth | 9 October | Isaac Watt | Resignation | Henry Turton |
| 1863 | Heathcote | 28 October | William Moorhouse | Resignation | Alfred Cox |
| 1863 | Akaroa | 30 October | Augustus White | Resignation | Lancelot Walker |
| 1864 | Franklin | 13 October | Marmaduke Nixon | Death (KIA) | Theodore Haultain |
| 1864 | Town of New Plymouth | 18 November | Henry Turton | Resignation | Charles Brown |
| 1864 | Waimea | 29 November | Alfred Saunders | Resignation | John Miles |
| 1865 (1st) | Bruce | 8 April | Thomas Gillies | Resignation | Arthur Burns |
| 1865 | Raglan | 19 April | Charles Taylor | Resignation | William Buckland |
| 1865 | Parnell | 20 April | Reader Wood | Resignation | Robert Creighton |
| 1865 | Town of New Plymouth | 19 May | Charles Brown | Resignation | Henry Sewell |
| 1865 | Gold Fields | 29 May | William Baldwin | Resignation | Charles Haughton |
| 1865 | Rangitiki | 10 July | William Fox | Resignation | Robert Pharazyn |
| 1865 | Omata | 18 July | James Richmond | Appointed to Legislative Council | Francis Gledhill |
| 1865 (2nd) | Bruce | 26 July | Edward Cargill | Resignation | James Macandrew |
| 1865 | Wairarapa | 29 July | Charles Carter | Resignation | Henry Bunny |
| 4th Parliament (1866–1870) ||||||
| 1866 | Mount Herbert | 27 July | William Moorhouse | Chose to represent Westland | Thomas Potts |
| 1866 | Port Chalmers | 15 December | Thomas Dick | Resignation | Thomas Dick |
| 1867 | City of Dunedin | 19 January | William Reynolds | Resignation | William Reynolds |
| 1867 | City of Christchurch | 13 February | James FitzGerald | Resignation | William Travers |
| 1867 | Avon | 11 March | Crosbie Ward | Resignation | William Reeves |
| 1867 | City of Auckland West | 25 April | James Williamson | Resignation | Patrick Dignan |
| 1867 | Manuherikia | 27 April | William Baldwin | Resignation | David Mervyn |
| 1867 | Wanganui | 27 April | John Bryce | Resignation | Henry Harrison |
| 1867 | Town of New Plymouth | 29 April | John Richardson | Resignation | Harry Atkinson |
| 1867 | Raglan | 4 June | Joseph Newman | Resignation | James Farmer |
| 1867 | Parnell | 5 June | Frederick Whitaker | Resignation | Charles Heaphy |
| 1867 | Port Chalmers | 15 June | Thomas Dick | Resignation | David Main |
| 1867 | Waimea | 28 June | Arthur Oliver | Resignation | Edward Baigent |
| 1867 | Lyttelton | 1 July | Edward Hargreaves | Resignation | George Macfarlan |
| 1867 | Northern Division | 1 July | Thomas Henderson | Resignation | Thomas Macfarlane |
| 1867 | Kaiapoi | 5 July | Joseph Beswick | Resignation | John Studholme |
| 1867 | Picton | 25 July | Arthur Beauchamp | Resignation | William Adams |
| 1867 | Pensioner Settlements | 5 August | Paul de Quincey | Resignation | John Kerr |
| 1867 | Ashley | 7 August | Lancelot Walker | Resignation | Henry Tancred |
| 1868 | Omata | 7 February | Arthur Atkinson | Resignation | Charles Brown |
| 1868 | Collingwood | 18 March | Andrew Richmond | Resignation | Arthur Collins |
| 1868 | Westland Boroughs | 3 April | William Moorhouse | Resignation | William Harrison |
| Supplementary election, 1868 ||||||
| Westland North | Westland North | 9 April 1868 | 9 April 1868 | 9 April 1868 | Timothy Gallagher |
| Westland South | Westland South | 6 April 1868 | 6 April 1868 | 6 April 1868 | Edmund Barff |
| First Māori elections ||||||
| Eastern Maori | Eastern Maori | 15 April 1868 | 15 April 1868 | 15 April 1868 | Tāreha Te Moananui |
| Northern Maori | Northern Maori | 15 April 1868 | 15 April 1868 | 15 April 1868 | Frederick Russell |
| Southern Maori | Southern Maori | 20 June 1868 | 20 June 1868 | 20 June 1868 | John Patterson |
| Western Maori | Western Maori | 1 May 1868 | 1 May 1868 | 1 May 1868 | Mete Kīngi Paetahi |
| By-election | Electorate | Date | Incumbent | Reason | Winner |
| 4th Parliament (continued) ||||||
| 1868 | Avon | 8 June | William Reeves | Resignation | William Rolleston |
| 1868 | Picton | 11 June | William Adams | Resignation | Courtney Kenny |
| 1868 | Rangitiki | 22 June | William Watt | Resignation | William Fox |
| 1868 | Franklin | 2 July | Robert Graham | Resignation | William Swan |
| 1868 | Waikouaiti | 27 July | William Murison | Resignation | Robert Mitchell |
| 1868 | Lyttelton | 2 November | George Macfarlan | Death | John Peacock |
| 1868 | Timaru | 20 November | Alfred Cox | Resignation | Edward Stafford |
| 1868 | City of Nelson | 24 December | Edward Stafford | Resignation | Nathaniel Edwards |
| 1869 | Marsden | 25 January | Francis Hull | Resignation | John Munro |
| 1869 | Roslyn | 12 February | George Hepburn | Resignation | Henry Driver |
| 1869 | City of Dunedin | 5 March | James Paterson | Resignation | Thomas Birch |
| 1869 | Northern Division | 15 March | James O'Neill | Resignation | Harry Farnall |
| 1869 | Newton | 19 March | George Graham | Resignation | Robert Creighton |
| 1869 | Waikouaiti | 27 April | Robert Mitchell | Resignation | Francis Rich |
| 1869 | Town of New Plymouth | 28 April | Harry Atkinson | Resignation | Thomas Kelly |
| 1869 (1st) | Wallace | 30 April | Alexander McNeill | Resignation | Cuthbert Cowan |
| 1869 | Oamaru | 25 May | Robert Campbell | Resignation | Charles Graham |
| 1869 | Taieri | 19 June | Donald Reid | Resignation | Henry Howorth |
| 1869 (2nd) | Wallace | 17 September | Cuthbert Cowan | Resignation | George Webster |
| 1870 | Bruce | 21 March | John Cargill | Resignation | James Brown |
| 1870 | Mongonui | 30 March | Thomas Ball | Resignation | Thomas Gillies |
| 1870 | Caversham | 25 April | Arthur John Burns | Resignation | James McIndoe |
| 1870 | Omata | 27 April | Charles Brown | Resignation | Frederic Carrington |
| 1870 | Parnell | 12 May | Charles Heaphy | Resignation | Reader Wood |
| 1870 | Riverton | 18 May | Donald Hankinson | Resignation | Lauchlan McGillivray |
| 1870 | Westland North | 2 July | Timothy Gallagher | Resignation | Thomas Kynnersley |
| 1870 | City of Christchurch | 12 August | William Travers | Resignation | William Moorhouse |
| 5th Parliament (1871–1875) ||||||
| 1871 | City of Auckland West | 1 September | John Williamson | Election Invalid | John Williamson |
| 1871 | Roslyn | 12 September | Henry Driver | Resignation | Edward McGlashan |
| 1872 | Wairau | 19 February | William Henry Eyes | Resignation | Arthur Seymour |
| 1872 | Waikato | 1 March | James McPherson | Resignation | William Jackson |
| 1872 | Wakatipu | 13 March | Charles Edward Haughton | Resignation | Bendix Hallenstein |
| 1872 | Rodney | 16 March | Harry Farnall | Resignation | John Sheehan |
| 1872 | City of Nelson | 27 May | Martin Lightband | Resignation | David Luckie |
| 1872 | Waikouaiti | 12 June | George McLean | Resignation | David Monro |
| 1872 | Coleridge | 23 July | John Karslake | Resignation | William Bluett |
| 1872 | Heathcote | 30 July | John Hall | Resignation | John Wilson |
| 1872 | Caversham | 28 August | Richard Cantrell | Resignation | William Tolmie |
| 1872 | Egmont | 3 October | William Gisborne | Resignation | Harry Atkinson |
| 1873 | Suburbs of Nelson | 14 May | Ralph Richardson | Resignation | Andrew Richmond |
| 1873 | Lyttelton | 19 May | John Peacock | Resignation | Henry Webb |
| 1873 | Invercargill | 22 May | William Henderson Calder | Resignation | John Cuthbertson |
| 1873 | Waikouaiti | 23 July | David Monro | Resignation | John Lillie Gillies |
| 1873 | Mongonui and Bay of Islands | 24 July | John McLeod | Resignation | John Williams |
| 1873 | Wakatipu | 19 August | Bendix Hallenstein | Resignation | Vincent Pyke |
| 1873 | Collingwood | 9 December | Arthur Collins | Resignation | William Gibbs |
| 1874 | Franklin | 9 April | Archibald Clark | Resignation | Joseph May |
| 1874 (1st) | Akaroa | 20 April | Robert Rhodes | Resignation | William Montgomery |
| 1874 | City of Dunedin | 23 April | John Bathgate | Resignation | Nathaniel Wales |
| 1874 | Waitemata | 3 August | Thomas Henderson | Resignation | Gustav von der Heyde |
| 1874 (2nd) | Akaroa | 10 August | William Montgomery | Election invalid | William Montgomery |
| 1874 | Waitemata | 16 September | Gustav von der Heyde | unseated on petition | Gustav von der Heyde |
| 1875 | Kaiapoi | 22 January | John Studholme | Resignation | Charles Bowen |
| 1875 (1st) | City of Auckland West | 27 March | Thomas Gillies | Appointed to Supreme Court | George Grey |
| 1875 (2nd) | City of Auckland West | 14 April | John Williamson | Death | Patrick Dignan |
| 1875 | Rangitikei | 24 April | William Fox | Resignation | John Ballance |
| 1875 | Waikouaiti | 3 May | John Lillie Gillies | Resignation | George McLean |
| 1875 | Wairau | 21 June | Arthur Seymour | Resignation | Joseph Ward |
| 1875 | Wallace | 6 August | George Webster | Death | Christopher Basstian |
| 1875 | Caversham | 20 August | William Tolmie | Death | Robert Stout |
| 6th Parliament (1876–1879) ||||||
| 1876 | City of Auckland West | 25 July | George Grey | Resignation | Benjamin Tonks |
| 1876 | Wanganui | 27 September | Julius Vogel | Resignation | William Fox |
| 1877 | Napier | 15 February | Donald McLean | Death | Fred Sutton |
| 1877 | City of Wellington | 27 March | Edward Pearce | Resignation | William Travers |
| 1877 | Totara | 30 April | George Henry Tribe | Death | William Gisborne |
| 1877 | City of Auckland West | 2 May | Benjamin Tonks | Resignation | James Wallis |
| 1877 | Wairarapa | 3 July | John Andrew | Resignation | George Beetham |
| 1878 | City of Wellington | 18 February | William Travers | Resignation | George Elliott Barton |
| 1878 | Parnell | 20 February | Reader Wood | Resignation | Frederick Moss |
| 1878 | Timaru | 8 April | Edward Stafford | Resignation | Richard Turnbull |
| 1878 | Port Chalmers | 12 April | William Reynolds | Resignation | James Green |
| 1878 | Franklin | 20 May | Hugh Lusk | Resignation | Richard Hobbs |
| 1878 | Cheviot | 21 May | Leonard Harper | Resignation | Alfred Saunders |
| 1878 | Grey Valley | 22 May | Martin Kennedy | Resignation | Richard Reeves |
| 1878 | Hokitika | 26 June | Charles Button | Resignation | Seymour Thorne George |
| 1878 | City of Dunedin | 3 July | William Larnach | Resignation | Richard Oliver |
| 1878 | Taieri | 11 July | Donald Reid | Resignation | William Cutten |
| 1878 | Invercargill | 17 July | George Lumsden | Resignation | Henry Feldwick |
| 1878 | Waipa | 24 July | Alfred Cox | Resignation | Edward Graham McMinn |
| 1878 | Roslyn | 29 July | Arthur John Burns | Resignation | Henry Driver |
| 1879 | Gladstone | 3 January | Frederick Teschemaker | Death | John Studholme |
| 1879 | Mataura | 15 January | William Wood | Resignation | James Shanks |
| 1879 | City of Nelson | 6 February | John Sharp | Resignation | Acton Adams |
| 1879 | City of Auckland West | 4 March | Patrick Dignan | Resignation | David Goldie |
| 1879 | Coleridge | 8 May | Cathcart Wason | Resignation | George Hart |
| 1879 | Hutt | 2 July | William Fitzherbert | Resignation | Henry Jackson |
| 1879 | Eastern Maori | 7 July | Karaitiana Takamoana | Death | Henare Tomoana |
| 1879 | Southern Maori | 7 July | Hōri Kerei Taiaroa | Resignation | Ihaia Tainui |
| 1879 | City of Dunedin | 15 July | Robert Stout | Resignation | William Downie Stewart |
| 7th Parliament (1879–1881) ||||||
| 1880 | Rangitikei | 8 May | William Jarvis Willis | Resignation | William Fox |
| 1880 | Waitaki | 16 June | Thomas William Hislop | Resignation | George Jones |
| 1880 | Waikaia | 21 September | George Ireland | Death | Horace Bastings |
| 1881 | Suburbs of Nelson | 11 January | Andrew Richmond | Death | Arthur Collins |
| 1881 | Southern Maori | 1 March | Ihaia Tainui | Resignation | Hōri Kerei Taiaroa |
| 1881 | City of Nelson | 7 June | Acton Adams | Resignation | Henry Levestam |
| 1881 | Grey Valley | 16 June | Edward Masters | Resignation | Thomas S. Weston |
| 8th Parliament (1882–1884) ||||||
| 1882 | Franklin North | 9 June | Benjamin Harris | Election declared void | Benjamin Harris |
| 1882 | Wakanui | 16 June | Cathcart Wason | Election declared void | Joseph Ivess |
| 1882 | Stanmore | 11 July | Walter Pilliet | Election declared void | Walter Pilliet |
| 1883 | Peninsula | 22 January | James Seaton | Death | William Larnach |
| 1883 | Selwyn | 6 April | John Hall | Resignation | Edward Lee |
| 1883 | Inangahua | 14 May | Thomas S. Weston | Resignation | Edward Shaw |
| 1883 | Bruce | 29 June | James Rutherford | Death | James McDonald |
| 1884 | Selwyn | 15 February | Edward Lee | Death | Edward Wakefield |
| 1884 | Thorndon | 13 May | William Levin | Resignation | Alfred Newman |
| 1884 | Kaiapoi | 16 May | Isaac Wilson | Resignation | Edward Richardson |
| 1884 | East Coast | 16 June | Allan McDonald | Resignation | Samuel Locke |
| 9th Parliament (1884–1887) ||||||
| 1885 | Oamaru | 20 May | Samuel Shrimski | Resignation | Thomas William Hislop |
| 1885 (1st) | Tauranga | 22 May | George Morris | Resignation | John Sheehan |
| 1885 | Waimea | 3 June | Joseph Shephard | Resignation | John Kerr |
| 1885 | Southern Maori | 10 June | Hōri Kerei Taiaroa | Resignation | Tame Parata |
| 1885 | Wakanui | 6 July | John Grigg | Resignation | Joseph Ivess |
| 1885 (2nd) | Tauranga | 11 July | John Sheehan | Death | Lawrence Grace |
| 1885 | Bruce | 5 August | Robert Gillies | Resignation | Donald Reid |
| 1886 | Sydenham | 12 May | William White | Resignation | Richard Taylor |
| 1886 | Dunedin Central | 19 October | James Bradshaw | Death | Thomas Bracken |
| 1886 | Waitemata | 11 December | William Hurst | Death | Richard Monk |
| 1886 | Western Maori | 23 December | Te Puke Te Ao | Death | Hoani Taipua |
| 1887 | Heathcote | 8 February | John Coster | Death | Frederic Jones |
| 1887 | Port Chalmers | 6 April | James Macandrew | Death | James Mills |
| 1887 | Te Aro | 15 April | Charles Johnston | Resignation | Francis Fraser |
| 1887 | Northern Maori | 9 May | Ihaka Hakuene | Death | Wi Katene |
| 1887 | Avon | 1 June | Leonard Harper | Resignation | Edwin Blake |
| 10th Parliament (1887–1890) ||||||
| 1888 | Ashley | 25 July | William Pearson | Death | John Verrall |
| 1889 | Lincoln | 16 January | Arthur O'Callaghan | Resignation | Alfred Saunders |
| 1889 | City of Nelson | 3 April | Henry Levestam | Death | Joseph Harkness |
| 1889 | Christchurch North | 19 June | Julius Vogel | Resignation | Edward Humphreys |
| 1889 | Oamaru | 30 September | Thomas William Hislop | Resignation | Thomas William Hislop |
| 1889 | Waipa | 21 November | William Jackson | Death | John Bryce |
| 1889 | East Coast | 13 December | Andrew Graham | Resignation | Alexander Creighton Arthur |
| 1890 | Timaru | 18 August | Richard Turnbull | Death | William Hall-Jones |

## Liberal Party era

Key
Liberal  Conservative  Independent Liberal  Liberal–Labour  Independent
| Electorate and by-election | Electorate and by-election | Date | Incumbent | Cause | Winner |
| 11th Parliament (1891–1893) ||||||||
| Northern Maori | 1891 | 7 February | Sydney Taiwhanga | Death | Eparaima Te Mutu Kapa |
| Egmont | 1891 | 17 February | Harry Atkinson | Appointed to Legislative Council | Felix McGuire |
| Newton | 1891 | 31 March | David Goldie | Resignation | Sir George Grey |
| Te Aroha | 1891 | 9 July | William Allen | Disallowed on petition | William Fraser |
| Waikato | 1891 | 6 October | John Bryce | Resignation | Edward Lake |
| City of Christchurch | 1891 | 9 October | Westby Perceval | Appointed Agent General | Ebenezer Sandford |
| City of Wellington | 1892 | 15 January | Kennedy Macdonald | Resignation | William McLean |
| Bruce | 1892 | 4 May | James Thomson | Resignation | James Allen |
| Rangitikei | 1892 | 8 July | Douglas Macarthur | Death | Robert Bruce |
| Inangahua | 1893 | 8 June | Richard Reeves | Bankruptcy | Sir Robert Stout |
| Wanganui | 1893 | 9 June | John Ballance | Death | Archibald Willis |
| Thames | 1893 | 26 July | Alfred Cadman | Resignation | James McGowan |
| City of Auckland | 1893 | 4 August | William Rees | Resignation | Alfred Cadman |
| 12th Parliament (1894–1896) ||||||||
| Waitemata | 1894 | 9 April | Richard Monk | Election declared invalid | William Massey |
| Tuapeka | 1894 | 9 July | Vincent Pyke | Death | William Larnach |
| City of Auckland | 1895 | 24 July | Sir George Grey | Resignation | Thomas Thompson |
| City of Christchurch | 1896 | 13 February | William Pember Reeves | Appointed Agent-General | Charles Lewis |
| 13th Parliament (1897–1899) ||||||||
| Suburbs of Wellington | 1897 | 23 April | Thomas Wilford | Election declared void | Charles Wilson |
| Awarua | 1897 | 5 August | Sir Joseph Ward | Bankruptcy | Sir Joseph Ward |
| City of Dunedin | 1897 | 13 October | Henry Fish | Death | Alexander Sligo |
| City of Wellington | 1898 | 9 March | Sir Robert Stout | Resignation | John Duthie |
| Mataura | 1898 | 26 May | George Richardson | Bankruptcy | Robert McNab |
| Tuapeka | 1898 | 2 November | William Larnach | Death | Charles Rawlins |
| City of Wellington | 1899 | 25 July | John Hutcheson | Resignation | John Hutcheson |
| 14th Parliament (1900–1902) ||||||||
| Otaki | 1900 | 6 January | Henry Augustus Field | Death | William Hughes Field |
| City of Auckland | 1900 | 27 April | William Crowther | Death | Joseph Witheford |
| Waihemo | 1900 | 18 July | John McKenzie | Resignation | Thomas Mackenzie |
| Northern Maori | 1901 | 9 January | Hone Heke Ngapua | Bankruptcy | Hone Heke Ngapua |
| City of Christchurch | 1901 | 18 July | Charles Lewis | Resignation | George Smith |
| Patea | July 1901 | 18 July | George Hutchison | Resignation | Frederick Haselden |
| Patea | November 1901 | 6 November | Frederick Haselden | Election voided on petition | Frederick Haselden |
| Caversham | 1901 | 19 December | Arthur Morrison | Death | Thomas Sidey |
| 15th Parliament (1903–1905) ||||||||
| Pahiatua | 1904 | 28 July | John O'Meara | Death | Bill Hawkins |
| City of Wellington | 1905 | 6 April | George Fisher | Death | Frank Fisher |
| 16th Parliament (1906–1908) ||||||||
| Westland | 1906 | 13 July | Richard Seddon | Death | Tom Seddon |
| Manukau | 1906 | 6 December | Matthew Kirkbride | Death | Frederic Lang |
| Taranaki | 1907 | 4 May | Edward Smith | Death | Henry Okey |
| Tuapeka | 1908 | 5 June | James Bennet | Death | William Chapple |
| 17th Parliament (1909–1911) ||||||||
| Thames | 1909 | 4 February | James McGowan | Appointed to Legislative Council | Edmund Taylor |
| Northern Maori | 1909 | 20 March | Hone Heke Ngapua | Death | Peter Buck |
| Rangitikei | 1909 | 16 September | Arthur Remington | Death | Robert Smith |
| Auckland East | 1910 | 16 June | Frederick Baume | Death | Arthur Myers |
| Christchurch North | 1911 | 17 August | Tommy Taylor | Death | Leonard Isitt |

## Multi-party era

Key
| Liberal | Reform | Social Democrat | Independent |
| Labour | Country Party | Independent Labour | United | Ratana |
| Electorate and by-election | Electorate and by-election | Date | Incumbent | Cause | Winner |
| 18th Parliament (1912–1914) ||||||||
| Egmont | 1912 | 17 September | Thomas Mackenzie | Resignation | Charles Wilkinson |
| Grey | 1913 | 17 & 24 July | Arthur Guinness | Death | Paddy Webb |
| Lyttelton | 1913 | 9 & 16 December | George Laurenson | Death | James McCombs |
| 19th Parliament (1915–1919) ||||||||
| Dunedin Central | 1915 | 3 February | Charles Statham | Resignation | Charles Statham |
| Bay of Islands | 1915 | 8 June | Vernon Reed | Election declared void | William Stewart |
| Taumarunui | 1915 | 15 June | William Jennings | Election declared void | William Jennings |
| Pahiatua | 1916 | 17 August | James Escott | Death | Harold Smith |
| Hawke's Bay | 1917 | 8 March | Robert McNab | Death | John Findlay |
| Bay of Islands | 1917 | 17 March | William Stewart | Resignation | Vernon Reed |
| Grey | 1917 | 24 November | Paddy Webb | Resignation | Paddy Webb |
| Wellington North | 1918 | 12 February | Alexander Herdman | Resignation | John Luke |
| Southern Maori | 1918 | 21 February | Taare Parata | Death | Hopere Uru |
| Grey | 1918 | 29 May | Paddy Webb | Imprisonment | Harry Holland |
| Wellington Central | 1918 | 3 October | Robert Fletcher | Death | Peter Fraser |
| Taranaki | 1918 | 10 October | Henry Okey | Death | Sydney Smith |
| Palmerston | 1918 | 19 December | David Buick | Death | Jimmy Nash |
| Wellington South | 1918 | 19 December | Alfred Hindmarsh | Death | Bob Semple |
| 20th Parliament (1920–1922) ||||||||
| Bruce | 1920 | 14 April | James Allen | Resignation | John Edie |
| Stratford | 1920 | 6 May | Robert Masters | Election declared void | Robert Masters |
| Bay of Plenty | 1920 | 30 September | William MacDonald | Death | Kenneth Williams |
| Patea | 1921 | 13 April | Walter Powdrell | Death | Edwin Dixon |
| Auckland East | 1921 | 2 November | Arthur Myers | Resignation | Clutha Mackenzie |
| Southern Maori | 1922 | 25 January | Hopere Uru | Death | Henare Uru |
| Dunedin North | 1922 | 21 June | Edward Kellett | Death | Jim Munro |
| 21st Parliament (1923–1925) ||||||||
| Tauranga | 1923 | 28 March | William Herries | Death | Charles Macmillan |
| Oamaru | 1923 | 1 May | John MacPherson | Election declared void | John Macpherson |
| Franklin | 1925 | 17 June | William Massey | Death | Ewen McLennan |
| 22nd Parliament (1926–1928) ||||||||
| Eden | 1926 | 15 April | James Parr | Appointed High Commissioner, UK | Rex Mason |
| Raglan | 1927 | 29 September | Richard Bollard | Death | Lee Martin |
| 23rd Parliament (1929–1931) ||||||||
| Bay of Islands | 1929 | 10 April | Harold Rushworth | Election declared void | Harold Rushworth |
| Hutt | 1929 | 18 December | Thomas Wilford | Resignation | Walter Nash |
| Parnell | 1930 | 7 May | Harry Jenkins | Resignation | Bill Endean |
| Invercargill | 1930 | 13 August | Sir Joseph Ward | Death | Vincent Ward |
| Waipawa | 1930 | 8 October | Sir George Hunter | Death | Albert Jull |
| Western Maori | 1930 | 8 October | Sir Māui Pōmare | Death | Taite Te Tomo |
| Hauraki | 1931 | 27 May | Arthur Hall | Death | Walter Massey |
| 24th Parliament (1932–1935) ||||||||
| Southern Maori | 1932 | 3 August | Tuiti Makitanara | Death | Eruera Tirikatene |
| Motueka | 1932 | 1 December | George Black | Death | Keith Holyoake |
| Lyttelton | 1933 | 13 September | James McCombs | Death | Elizabeth McCombs |
| Buller | 1933 | 22 November | Harry Holland | Death | Paddy Webb |
| Lyttelton | 1935 | 24 July | Elizabeth McCombs | Death | Terry McCombs |
| 25th Parliament (1936–1938) ||||||||
| Manukau | 1936 | 30 September | Bill Jordan | Appointed High Commissioner, UK | Arthur Osborne |

## Two-party era (1938–1996)

Key
Labour  National  Independent  Social Credit
| Electorate and by-election | Electorate and by-election | Date | Incumbent | Cause | Winner | Winner |
| 26th Parliament (1939–1943) ||||||||
| Christchurch South | 1939 | 3 June | Ted Howard | Death | | Robert Macfarlane |
| Auckland West | 1940 | 18 May | Michael Joseph Savage | Death | | Peter Carr |
| Waipawa | 1940 | 16 November | Albert Jull | Death | | Cyril Harker |
| Waitemata | 1941 | 19 July | Jack Lyon | Death | | Mary Dreaver |
| Bay of Plenty | 1941 | 13 December | Gordon Hultquist | Death | | Bill Sullivan |
| Mid-Canterbury | 1942 | 27 January | Arthur Grigg | Death | | Mary Grigg |
| Hauraki | 1942 | 7 February | John Allen | Death | | Andy Sutherland |
| Temuka | 1942 | 7 February | Thomas Burnett | Death | | Jack Acland |
| Christchurch East | 1943 | 6 February | Tim Armstrong | Death | | Mabel Howard |
| Northern Maori | 1943 | 19 June | Paraire Karaka Paikea | Death | (by-election postponed by legislation) | (by-election postponed by legislation) |
| 27th Parliament (1943–1946) ||||||||
| Awarua | 1944 | 28 October | James Hargest | Death | | George Herron |
| Western Maori | 1945 | 10 February | Toko Ratana | Death | | Matiu Ratana |
| Hamilton | 1945 | 26 May | Frank Findlay | Death | | Hilda Ross |
| Dunedin North | 1945 | 21 July | Jim Munro | Death | | Robert Walls |
| Raglan | 1946 | 5 March | Robert Coulter | Death | | Hallyburton Johnstone |
| 28th Parliament (1946–1949) ||||||||
| Avon | 1947 | 28 May | Dan Sullivan | Death | | Jock Mathison |
| Mount Albert | 1947 | 24 September | Arthur Richards | Death | | Warren Freer |
| Westland | 1947 | 3 December | James O'Brien | Death | | Jim Kent |
| 29th Parliament (1950–1951) ||||||||
| Brooklyn | 1951 | 17 February | Peter Fraser | Death | | Arnold Nordmeyer |
| 30th Parliament (1951–1954) ||||||||
| Dunedin North | 1953 | 12 December | Robert Walls | Death | | Ethel McMillan |
| Onehunga | 1953 | 19 December | Arthur Osborne | Death | | Hugh Watt |
| Onslow | 1954 | 7 July | Harry Combs | Death | | Henry May |
| Patea | 1954 | 31 July | William Sheat | Resignation | | William Sheat |
| 31st Parliament (1955–1957) ||||||||
| Riccarton | 1956 | 27 October | Angus McLagan | Death | | Mick Connelly |
| Bay of Plenty | 1957 | 6 April | Bill Sullivan | Resignation | | Percy Allen |
| 32nd Parliament (1958–1960) ||||||||
| Hamilton | 1959 | 2 May | Dame Hilda Ross | Death | | Lance Adams-Schneider |
| 33rd Parliament (1961–1963) ||||||||
| Hurunui | 1961 | 10 June | William Gillespie | Death | | Lorrie Pickering |
| Waitaki | 1962 | 10 March | Thomas Hayman | Death | | Allan Dick |
| Buller | 1962 | 7 July | Jerry Skinner | Death | | Bill Rowling |
| Timaru | 1962 | 21 July | Clyde Carr | Resignation | | Sir Basil Arthur |
| Otahuhu | 1963 | 16 March | James Deas | Death | | Bob Tizard |
| Northern Maori | 1963 | 16 March | Tapihana Paikea | Death | | Matiu Rata |
| Grey Lynn | 1963 | 18 May | Fred Hackett | Death | | Reginald Keeling |
| 34th Parliament (1964–1966) ||||||||
| There were no by-elections during the term of the 34th Parliament. ||||||||
| 35th Parliament (1967–1969) ||||||||
| Southern Maori | 1967 | 11 March | Sir Eruera Tirikatene | Death | | Whetu Tirikatene-Sullivan |
| Fendalton | 1967 | 15 April | Harry Lake | Death | | Eric Holland |
| Petone | 1967 | 15 April | Michael Moohan | Death | | Fraser Colman |
| Eastern Maori | 1967 | 12 August | Puti Tipene Watene | Death | | Paraone Reweti |
| Palmerston North | 1967 | 2 December | Bill Brown | Death | | Joe Walding |
| Hutt | 1968 | 3 August | Sir Walter Nash | Death | | Trevor Young |
| 36th Parliament (1970–1972) ||||||||
| Marlborough | 1970 | 21 February | Tom Shand | Death | | Ian Brooks |
| 37th Parliament (1973–1975) ||||||||
| Sydenham | 1974 | 2 November | Norman Kirk | Death | | John Kirk |
| 38th Parliament (1976–1978) ||||||||
| Nelson | 1976 | 28 February | Sir Stanley Whitehead | Death | | Mel Courtney |
| Mangere | 1977 | 26 March | Colin Moyle | Resignation | | David Lange |
| Pahiatua | 1977 | 30 April | Sir Keith Holyoake | Appointed as Governor-General | | John Falloon |
| Rangitikei | 1978 | 18 February | Sir Roy Jack | Death | | Bruce Beetham |
| 39th Parliament (1979–1981) ||||||||
| Christchurch Central | 1979 | 18 August | Bruce Barclay | Death | | Geoffrey Palmer |
| Northern Maori | 1980 | 7 June | Matiu Rata | Resignation | | Bruce Gregory |
| Onehunga | 1980 | 7 June | Frank Rogers | Death | | Fred Gerbic |
| East Coast Bays | 1980 | 6 September | Frank Gill | Appointed as Ambassador to US | | Gary Knapp |
| 40th Parliament (1982–1984) ||||||||
| There were no by-elections during the term of the 40th Parliament. ||||||||
| 41st Parliament (1984–1987) ||||||||
| Timaru | 1985 | 15 June | Sir Basil Arthur | Death | | Maurice McTigue |
| 42nd Parliament (1987–1990) ||||||||
| There were no by-elections during the term of the 42nd Parliament. ||||||||
| 43rd Parliament (1990–1993) ||||||||
| Tamaki | 1992 | 15 February | Sir Robert Muldoon | Resignation | | Clem Simich |
| Wellington Central | 1992 | 12 December | Fran Wilde | Election as Mayor of Wellington | | Chris Laidlaw |
| Tauranga | 1993 | 17 April | Winston Peters | Resignation | | Winston Peters |
| 44th Parliament (1993–1996) ||||||||
| Selwyn | 1994 | 13 August | Ruth Richardson | Resignation | | David Carter |

## MMP era (1996–present)

Key
National  Labour  Māori Party  Independent  Mana  NZ First
| Electorate and by-election | Electorate and by-election | Date | Incumbent | Incumbent | Cause | Winner |
| 45th Parliament (1996–1999) ||||||||
| Taranaki-King Country | 1998 | 2 May | | Jim Bolger | Resignation; appointed ambassador to Washington | Shane Ardern |
| 46th Parliament (1999–2002) ||||||||
| There were no by-elections during the term of the 46th Parliament. ||||||||
| 47th Parliament (2002–2005) ||||||||
| Te Tai Hauauru | 2004 | 10 July | | Tariana Turia | Resignation | Tariana Turia |
| 48th Parliament (2005–2008) ||||||||
| There were no by-elections during the term of the 48th Parliament. ||||||||
| 49th Parliament (2008–2011) ||||||||
| Mount Albert | 2009 | 13 June | | Helen Clark | Resignation; appointed to the UNDP | David Shearer |
| Mana | 2010 | 20 November | | Winnie Laban | Resignation | Kris Faafoi |
| Botany | 2011 | 5 March | | Pansy Wong | Resignation | Jami-Lee Ross |
| Te Tai Tokerau | 2011 | 25 June | | Hone Harawira | Resignation; established the Mana Movement | Hone Harawira |
| 50th Parliament (2011–2014) ||||||||
| Ikaroa-Rāwhiti | 2013 | 29 June | | Parekura Horomia | Death | Meka Whaitiri |
| Christchurch East | 2013 | 30 November | | Lianne Dalziel | Resignation; elected Mayor of Christchurch | Poto Williams |
| 51st Parliament (2014–2017) ||||||||
| Northland | 2015 | 28 March | | Mike Sabin | Resignation | Winston Peters |
| Mount Roskill | 2016 | 3 December | | Phil Goff | Resignation; elected Mayor of Auckland | Michael Wood |
| Mount Albert | 2017 | 25 February | | David Shearer | Resignation; appointed to head the United Nations Mission in South Sudan | Jacinda Ardern |
| 52nd Parliament (2017–2020) ||||||||
| Northcote | 2018 | 9 June | | Jonathan Coleman | Resignation | Dan Bidois |
| 53rd Parliament (2020–2023) ||||||||
| Tauranga | 2022 | 18 June | | Simon Bridges | Resignation | Sam Uffindell |
| Hamilton West | 2022 | 10 December | | Gaurav Sharma | Resignation | Tama Potaka |
| 54th Parliament (2023–present) ||||||||
| Port Waikato | 2023 | 25 November | n/a | n/a | Death of candidate after close of nominations | Andrew Bayly |