The list of by-elections in the Province of Canada includes every by-election held in the Province of Canada from its creation in 1841 until Confederation in 1867. By-elections occurred whenever there was a vacancy in the Legislative Assembly. The Legislative Council was made an elective body in 1856 and by-elections occurred there as well. Due to the fluid nature of party allegiances during this time no attempt has been made to show them in this list.
A by-election occurs whenever there was a vacancy in the legislature. Vacancies occurred for the following reasons:
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Oxford North | July 14, 1866 | Hope Fleming Mackenzie | Thomas Oliver | Death |
| Wentworth North | November 1, 1865 | William Notman | James McMonies | Death |
| Hamilton | February 21, 1865 | Isaac Buchanan | Charles Magill | Resignation |
| Ontario South | January 18, 1865 | Oliver Mowat | Thomas Nicholson Gibbs | Appointed a judge |
| Trois-Rivières | January 16, 1865 | Joseph-Édouard Turcotte | Louis-Charles Boucher de Niverville | Death |
| Chicoutimi and Saguenay | January 3, 1865 | David Edward Price | Pierre-Alexis Tremblay | Resignation to run for the Legislative Council |
| York West | December 14, 1864 | William Pearce Howland | William Pearce Howland | Sought re-election upon appointment as Postmaster General |
| Lanark North | November 4, 1864 | Robert Bell | William McDougall | Resignation to provide a seat for McDougall |
| Peterborough | September 14, 1864 | Wilson Seymour Conger | Frederick W. Haultain | Death |
| Niagara | September 7, 1864 | John Simpson | Angus Morrison | Appointed Assistant Auditor of Public Accounts |
| Jacques-Cartier | August 26, 1864 | François-Zéphirin Tassé | Guillaume Gamelin Gaucher | Appointed Inspector of Prisons |
| Ontario North | July 30, 1864 | William McDougall | Matthew Crooks Cameron | Sought re-election upon appointment as Provincial Secretary and Registrar |
| Ontario South | July 18, 1864 | Oliver Mowat | Oliver Mowat | Sought re-election upon appointment as Postmaster General |
| Oxford South | July 11, 1864 | George Brown | George Brown | Sought re-election upon appointment as President of the Executive Council |
| Hamilton | April 29, 1864 | Isaac Buchanan | Isaac Buchanan | Sought re-election upon appointment as President of the Executive Council |
| Waterloo North | April 26, 1864 | Michael Hamilton Foley | Isaac Erb Bowman | Sought re-election upon appointment as Postmaster General |
| Northumberland West | April 23, 1864 | James Cockburn | James Cockburn | Sought re-election upon appointment as Solicitor General for Upper Canada |
| Kamouraska | April 14, 1864 | Jean-Charles Chapais | Jean-Charles Chapais | Sought re-election upon appointment as Commissioner of Public Works |
| Sherbrooke | April 11, 1864 | Alexander Tilloch Galt | Alexander Tilloch Galt | Sought re-election upon appointment as Minister of Finance |
| Niagara | April 11, 1864 | John Simpson | John Simpson | Sought re-election upon appointment as Provincial Secretary and Registrar |
| Montreal West | April 11, 1864 | Thomas D'Arcy McGee | Thomas D'Arcy McGee | Sought re-election upon appointment as Minister of Agriculture |
| Montreal East | April 11, 1864 | George-Étienne Cartier | George-Étienne Cartier | Sought re-election upon appointment as Attorney General for Lower Canada |
| Kingston | April 11, 1864 | John A. Macdonald | John A. Macdonald | Sought re-election upon appointment as Attorney General for Upper Canada |
| Dorchester | April 11, 1864 | Hector-Louis Langevin | Hector-Louis Langevin | Sought re-election upon appointment as Solicitor General for Lower Canada |
| Leeds South | January 30, 1864 | Albert Norton Richards | David Ford Jones | Sought re-election upon appointment as Solicitor General for Upper Canada |
| St. Hyacinthe | October 1, 1863 | Louis-Victor Sicotte | Rémi Raymond | Appointed a judge |
| Bagot | August 15, 1863 | Maurice Laframboise | Maurice Laframboise | Sought re-election upon appointment as Commissioner of Public Works |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Essex | April 7, 1863 | Arthur Rankin | John O'Connor | Void Election |
| Laprairie | April 1, 1863 | Thomas-Jean-Jacques Loranger | Alfred Pinsonneault | Appointed a judge |
| Oxford South | March 19, 1863 | George Skeffington Connor | George Brown | Appointed a judge |
| Napierville | November 17, 1862 | Jacques-Olivier Bureau | Pierre Benoît | Resignation to run for the Legislative Council |
| Perth | July 3, 1862 | Michael Hamilton Foley | Thomas Mayne Daly | Elected in two seats and re-elected at ministerial by-election in Waterloo North |
| Hochelaga | June 20, 1862 | Paschal Falkner | Antoine-Aimé Dorion | Resignation to provide a seat for Dorion |
| Oxford North | June 14, 1862 | William McDougall | William McDougall | Sought re-election upon appointment as Commissioner of Crown Lands |
| Cornwall | June 14, 1862 | John Sandfield Macdonald | John Sandfield Macdonald | Sought re-election upon appointment as Attorney General for Upper Canada |
| York North | June 13, 1862 | Adam Wilson | Adam Wilson | Sought re-election upon appointment as Solicitor General for Upper Canada |
| York West | June 12, 1862 | William Pearce Howland | William Pearce Howland | Sought re-election upon appointment as Minister of Finance |
| St. Hyacinthe | June 12, 1862 | Louis-Victor Sicotte | Louis-Victor Sicotte | Sought re-election upon appointment as Attorney General for Lower Canada |
| Argenteuil | June 12, 1862 | John Abbott | John Abbott | Sought re-election upon appointment as Solicitor General for Lower Canada |
| Waterloo North | June 9, 1862 | Michael Hamilton Foley | Michael Hamilton Foley | Sought re-election upon appointment as Postmaster General |
| Quebec County | June 9, 1862 | François Évanturel | François Évanturel | Sought re-election upon appointment as Minister of Agriculture |
| Montreal West | June 5, 1862 | Thomas D'Arcy McGee | Thomas D'Arcy McGee | Sought re-election upon appointment as President of the Executive Council |
| Toronto West | April 22, 1862 | John Beverley Robinson | John Beverley Robinson | Sought re-election upon appointment as President of the Executive Council |
| London | April 7, 1862 | John Carling | John Carling | Sought re-election upon appointment as Receiver General |
| Brome | March 17, 1862 | Moses Sweet | Christopher Dunkin | Appointed Postmaster of Warden |
| Montcalm | February 20, 1862 | Jean-Louis Martin | Joseph Dufresne | Death |
| Laval | September 27, 1861 | Pierre Labelle | Louis-Siméon Morin | Appointed Inspector of Public Works |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Grey | March 4, 1861 | John Sheridan Hogan | Jesse Thomas Purdy | Death |
| Vaudreuil | November 26, 1860 | Robert Unwin Harwood | Jean-Baptiste Mongenais | Resignation to run for the Legislative Council |
| Shefford | November 20, 1860 | Asa Belknap Foster | Vacant, no return made due to tie between Lucius Seth Huntington and Michel-Adrien Bessette. Assembly dissolved before the results could be decided. | Resignation to run for the Legislative Council |
| Lambton | November 19, 1860 | Malcolm Cameron | Hope Fleming Mackenzie | Resignation to run for the Legislative Council |
| Lincoln | November 7, 1860 | William Hamilton Merritt | John Charles Rykert | Resignation to run for the Legislative Council |
| Lanark North | October 26, 1860 | Robert Bell | Robert Bell | Resignation to run for the Legislative Council |
| Middlesex East | May 31, 1860 | Marcus Talbot | Robert Craik | Death |
| Quebec East* | May 18, 1860 | Hippolyte Dubord | Pierre-Gabriel Huot | Void Election |
| Quebec West* | May 7, 1860 | Charles Joseph Alleyn | Charles Joseph Alleyn | Void Election |
| Quebec Centre* | May 7, 1860 | Georges-Honoré Simard | Georges-Honoré Simard | Void Election |
| Terrebonne | February 21, 1860 | Louis-Siméon Morin | Louis-Siméon Morin | Sought re-election upon appointment as Solicitor General for Lower Canada |
| York North | January 14, 1860 | Joseph Hartman | Adam Wilson | Death |
| Russell | December 21, 1859 | G. B. Lyon-Fellowes | John Loux | Resignation due to election fraud |
| Wellington North | February 23, 1859 | Charles Allan | James Ross | Death |
| Maskinongé | December 14, 1858 | Louis-Honoré Gauvreau | George Caron | Death |
| Brant East | December 1, 1858 | David Christie | Hugh Finlayson | Resignation to run for the Legislative Council |
| Haldimand | October 7, 1858 | William Lyon Mackenzie | Michael Harcourt | Resignation |
| Lotbinière | October 2, 1858 | John O'Farrell | Lewis Thomas Drummond | Void Election |
| Shefford | September 14, 1858 | Lewis Thomas Drummond | Asa Belknap Foster | Sought re-election upon appointment as Attorney General for Lower Canada** |
| Portneuf | September 11, 1858 | Joseph-Élie Thibaudeau | Joseph-Élie Thibaudeau | Sought re-election upon appointment as President of the Executive Council and Minister of Agriculture** |
| Montreal | September 9, 1858 | Antoine-Aimé Dorion | Antoine-Aimé Dorion | Sought re-election upon appointment as Commissioner of Crown Lands** |
| Oxford South | September 7, 1858 | George Skeffington Connor | George Skeffington Connor | Sought re-election upon appointment as Solicitor General for Upper Canada** |
| Iberville | September 6, 1858 | Charles Laberge | Charles Laberge | Sought re-election upon appointment as Solicitor General for Lower Canada** |
| Ontario South | September 4, 1858 | Oliver Mowat | Oliver Mowat | Sought re-election upon appointment as Provincial Secretary and Registrar** |
| Brockville | September 2, 1858 | George Sherwood | George Sherwood | Sought re-election upon appointment as Receiver General |
| Toronto | September 1, 1858 | George Brown | George Brown | Sought re-election upon appointment as Inspector General** |
| Cornwall | September 1, 1858 | John Sandfield Macdonald | John Sandfield Macdonald | Sought re-election upon appointment as Attorney General for Upper Canada** |
| Lévis | August 28, 1858 | François-Xavier Lemieux | François-Xavier Lemieux | Sought re-election upon appointment as Receiver General** |
| Waterloo North | August 23, 1858 | Michael Hamilton Foley | Michael Hamilton Foley | Sought re-election upon appointment as Postmaster General** |
| Sherbrooke | August 23, 1858 | Alexander Tilloch Galt | Alexander Tilloch Galt | Sought re-election upon appointment as Inspector General |
| Wellington North | August 21, 1858 | Charles Allan | Charles Allan | Void Election |
| Middlesex West | August 5, 1858 | John Scatcherd | Angus Peter McDonald | Death |
| Leeds North and Grenville North | May 21, 1858 | Basil R. Church | Ogle Robert Gowan | Death |
| Oxford North | May 14, 1858 | George Brown | William McDougall | Chose to sit for Toronto |
| Renfrew | March 3, 1858 | John Lorn McDougall | William Cayley | Appointed Associate Coroner for the United Counties of Lanark and Renfrew |
| Northumberland West | February 22, 1858 | Sidney Smith | Sidney Smith | Sought re-election upon appointment as Postmaster General |
* Incumbents sat for Quebec City which was a three-member seat until 1860 when it was split into Centre, East and West districts. As a result, the by-elections were held for the new single-member seats
** Members of the Brown-Dorion Ministry of August 2–4, 1858
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Terrebonne | June 23, 1857 | Gédéon-Mélasippe Prévost | Louis-Siméon Morin | Resignation to provide a seat for Morin |
| Quebec City | April 14, 1857 | Jean Blanchet | George Okill Stuart | Resignation (ill health) |
| Rimouski | February 17, 1857 | Joseph-Charles Taché | Michel Guillaume Baby | Resignation |
| Quebec City | October 27, 1856 | Jean Chabot | Georges-Honoré Simard | Appointed a judge |
| Hastings North | October 27, 1856 | Edmund Murney | George Benjamin | Resignation to run for the Legislative Council |
| Rouville | October 4, 1856 | Joseph-Napoléon Poulin | William Henry Chaffers | Resignation to run for the Legislative Council |
| Niagara | June 20, 1856 | Joseph Curran Morrison | Joseph Curran Morrison | Sought re-election upon appointment as Receiver General |
| Stanstead | June 10, 1856 | Timothy Lee Terrill | Timothy Lee Terrill | Sought re-election upon appointment as Provincial Secretary and Registrar |
| Argenteuil | May 12, 1856 | Sydney Robert Bellingham | Sydney Robert Bellingham | Void Election |
| Renfrew | March 31, 1856 | Francis Hincks | John Supple | Resignation |
| Peterborough | January 26, 1856 | John Langton | Wilson Seymour Conger | Appointed Auditor of Public Accounts |
| Quebec County | August 7, 1855 | Pierre-Joseph-Olivier Chauveau | François Évanturel | Appointed Superintendent of the Board of Education |
| Chicoutimi and Tadoussac | April 26, 1855 | Augustin-Norbert Morin | David Edward Price | Appointed a judge |
| Verchères | February 28, 1855 | George-Étienne Cartier | George-Étienne Cartier | Sought re-election upon appointment as Provincial Secretary and Registrar |
| Montmorency | February 12, 1855 | Joseph-Édouard Cauchon | Joseph-Édouard Cauchon | Sought re-election upon appointment as Commissioner of Crown Lands |
| Lévis | February 10, 1855 | François-Xavier Lemieux | François-Xavier Lemieux | Sought re-election upon appointment as Chief Commissioner of Public Works |
| Kamouraska | January 30, 1855 | Jean-Charles Chapais | Jean-Charles Chapais | Void Election |
| Saguenay | January 8, 1855 | Pierre-Gabriel Huot | Pierre-Gabriel Huot | Void Election |
| Argenteuil | January 5, 1855 | Sydney Robert Bellingham | Sydney Robert Bellingham | Void Election |
| Bagot | October 20, 1854 | Timothée Brodeur | Timothée Brodeur | Void Election |
| Bellechasse | October 17, 1854 | Jean Chabot | Octave-Cyrille Fortier | Chose to sit for Quebec City |
| Wentworth North | October 13, 1854 | Robert Spence | Robert Spence | Sought re-election upon appointment as Postmaster General |
| Oxford South | October 9, 1854 | Francis Hincks | Ephraim Cook | Chose to sit for Renfrew |
| Huron-Bruce | October 4, 1854 | William Cayley | William Cayley | Sought re-election upon appointment as Inspector General |
| Hamilton | October 2, 1854 | Allan MacNab | Allan MacNab | Sought re-election upon appointment as President of the Executive Council and Minister of Agriculture |
| Kingston | September 28, 1854 | John A. Macdonald | John A. Macdonald | Sought re-election upon appointment as Attorney General of Upper Canada |
| Frontenac | September 28, 1854 | Henry Smith | Henry Smith | Sought re-election upon appointment as Solicitor General of Upper Canada |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Leeds | July 30, 1853 | William Buell Richards | Jesse Delong | Appointed a judge |
| Niagara | July 13, 1853 | Joseph Curran Morrison | Joseph Curran Morrison | Sought re-election upon appointment as Solicitor General of Upper Canada |
| Toronto | April 28, 1853 | William Henry Boulton | Henry Sherwood | Void Election |
| Sherbrooke City | March 8, 1853 | Edward Short | Alexander Tilloch Galt | Appointed a judge |
| Stanstead | November 23, 1852 | Hazard Bailey Terrill | Timothy Lee Terrill | Death |
| Bellechasse | October 4, 1852 | Jean Chabot | Jean Chabot | Sought re-election upon appointment as Chief Commissioner of Public Works |
| Niagara | September 25, 1852 | Francis Hincks | Joseph Curran Morrison | Chose to sit for Oxford |
| Deux-Montagnes | July 9, 1852 | William Henry Scott | Louis-Joseph Papineau | Death |
| Huron | May 12, 1852 | Malcolm Cameron | Malcolm Cameron | Sought re-election upon accepting appointment as President of the Executive Council |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Haldimand | April 21, 1851 | David Thompson | William Lyon Mackenzie | Death |
| Kamouraska | February 1, 1851 | Pierre Canac | Luc Letellier de St-Just | Death |
| Lincoln | May 4, 1850 | William Hamilton Merritt | William Hamilton Merritt | Sought re-election upon appointment as Chief Commissioner of Public Works |
| Mégantic | May 1, 1850 | Dominick Daly | Dunbar Ross | Appointed to a Commission Inquiring into the Condition and Claims of the New and Waltham forests |
| Halton | March 18, 1850 | John Wetenhall | Calen Hopkins | Sought re-election upon appointment as Assistant Commissioner of Public Works |
| Sherbrooke County | March 9, 1850 | Alexander Tilloch Galt | John Sewell Sanborn | Resignation |
| Quebec City | January 29, 1850 | Jean Chabot | Jean Chabot | Sought re-election upon appointment as Chief Commissioner of Public Works |
| London | January 21, 1850 | John Wilson | John Wilson | Sought re-election in opposition to the Montreal Annexation Manifesto |
| Glengarry | January 11, 1850 | John Sandfield Macdonald | John Sandfield Macdonald | Sought re-election upon appointment as Solicitor General for Upper Canada |
| York East | December 4, 1849 | William Hume Blake | Peter Perry | Appointed a judge |
| Chambly | September 25, 1849 | Pierre Beaubien | Louis Lacoste | Appointed Medical Superintendent at the Montreal prison |
| Sherbrooke County | April 17, 1849 | Samuel Brooks | Alexander Tilloch Galt | Death |
| Lincoln | October 6, 1848 | William Hamilton Merritt | William Hamilton Merritt | Sought re-election upon appointment as President of the Executive Council |
| Saguenay | September 5, 1848 | Marc-Pascal de Sales Laterrière | Marc-Pascal de Sales Laterrière | Vacated seat on appointment as Deputy Adjutant-General of the Militia. Re-elected after resigning office. |
| Shefford | July 11, 1848 | Lewis Thomas Drummond | Lewis Thomas Drummond | Sought re-election upon appointment as Solicitor General for Lower Canada |
| York East | July 5, 1848 | William Hume Blake | William Hume Blake | Sought re-election upon appointment as Solicitor General for Upper Canada |
| Quebec City | June 9, 1848 | Thomas Cushing Aylwin | François-Xavier Méthot | Appointed a judge |
| Oxford | April 28, 1848 | Francis Hincks | Francis Hincks | Sought re-election upon appointment as Inspector General |
| Trois-Rivières | April 26, 1848 | Vacant | Antoine Polette | No return made at general election |
| Terrebonne | April 14, 1848 | Louis-Hippolyte Lafontaine | Louis-Michel Viger | Elected in two seats and re-elected in ministerial by-election for Montreal City |
| Kent | April 10, 1848 | Malcolm Cameron | Malcolm Cameron | Sought re-election upon appointment as Assistant Commissioner of Public Works |
| Verchères | April 7, 1848 | James Leslie | George-Étienne Cartier | Vacated seat on appointment as President of the Executive Council and was later appointed to the Legislative Council |
| York North | April 1, 1848 | Robert Baldwin | Robert Baldwin | Sought re-election upon appointment as Attorney General for Upper Canada |
| York South | March 31, 1848 | James Hervey Price | James Hervey Price | Sought re-election upon appointment as Commissioner of Crown Lands |
| Quebec City | March 28, 1848 | Thomas Cushing Aylwin | Thomas Cushing Aylwin | Sought re-election upon appointment as Solicitor General for Lower Canada |
| Montreal City | March 28, 1848 | Louis-Hippolyte Lafontaine | Louis-Hippolyte Lafontaine | Sought re-election upon appointment as Attorney General for Lower Canada |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Dorchester | July 12, 1847 | Joseph-André Taschereau | François-Xavier Lemieux | Appointed a judge |
| London | July 3, 1847 | William Henry Draper | John Wilson | Appointed a judge |
| Toronto | June 10, 1847 | Henry Sherwood | Henry Sherwood | Sought re-election upon appointment as Attorney General for Upper Canada |
| Missisquoi | June 10, 1847 | James Smith | William Badgley | Appointed a judge |
| Kingston | June 1, 1847 | John A. Macdonald | John A. Macdonald | Sought re-election upon appointment as Receiver General |
| L'Islet | May 6, 1847 | Étienne-Paschal Taché | Charles-François Fournier | Appointed Deputy Adjutant-General of the Militia |
| Cornwall | August 17, 1846 | Rolland Macdonald | John Hillyard Cameron | Resignation to provide a seat for Cameron |
| Simcoe | July 27, 1846 | William Benjamin Robinson | William Benjamin Robinson | Sought re-election upon appointment as Chief Commissioner of Public Works |
| Prince Edward | July 1, 1846 | John Philip Roblin | Roger B. Conger | Appointed Collector of Customs |
| Carleton | June 23, 1846 | James Johnston | George Lyon | Sought re-election in opposition to the Ministry |
| Huron | February 28, 1846 | William Dunlop | William Cayley | Appointed Superintendent of the Lachine Canal |
| Dorchester | September 15, 1845 | Pierre-Elzéar Taschereau | Joseph-André Taschereau | Death |
| Trois-Rivières | July 14, 1845 | Edward Greive | Denis-Benjamin Viger | Death |
| Lanark | February 28, 1845 | Malcolm Cameron | Malcolm Cameron | Void Election |
| London | February 13, 1845 | Lawrence Lawrason | William Henry Draper | Resignation to provide a seat for Draper |
| Kent | February 7, 1845 | Samuel Harrison | Joseph Woods | Appointed a judge |
| Saguenay | January 14, 1845 | Augustin-Norbert Morin | Marc-Pascal de Sales Laterrière | Chose to sit for Bellechasse |
| Simcoe | January 13, 1845 | William Benjamin Robinson | William Benjamin Robinson | Sought re-election upon appointment as Inspector General |
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Montreal City | April 17, 1844 | Benjamin Holmes | Lewis Thomas Drummond | Resignation |
| London | January 1844 | Hamilton Hartley Killaly | Lawrence Lawrason | Resignation due to his office becoming ineligible with membership of the Legislature |
| Montreal City | November 22, 1843 | George Moffatt | Pierre Beaubien | Resignation in protest of moving the capital from Kingston to Montreal |
| Hastings | November 4, 1843 | Vacant | Edmund Murney | No by-election held in 1842 due to riots |
| Montreal County | October 26, 1843 | Alexandre-Maurice Delisle | André Jobin | Appointed Clerk of the Crown |
| Chambly | October 23, 1843 | John Yule | Louis Lacoste | Resignation |
| Rouville | September 25, 1843 | William Walker | Timothée Franchère | Resignation |
| Champlain | September 22, 1843 | René-Joseph Kimber | Henry Judah | Appointed to the Legislative Council |
| Quebec City | September 18, 1843 | David Burnet | Jean Chabot | Resignation (became bankrupt) |
| Russell | September 14, 1843 | William Henry Draper | William Stewart | Appointed to the Legislative Council |
| Toronto | March 6, 1843 | Isaac Buchanan | Henry Sherwood | Resignation |
| Rimouski | January 30, 1843 | Michel Borne | Robert Baldwin | Resignation to provide a seat for Baldwin |
| Saguenay | November 28, 1842 | Étienne Parent | Augustin-Norbert Morin | Appointed Clerk of the Executive Council |
| 2nd Riding of York | November 22, 1842 | George Duggan | George Duggan | Void Election |
| Beauharnois | November 9, 1842 | John William Dunscomb | Edward Gibbon Wakefield | Appointed Warden of Trinity House |
| Portneuf | October 20, 1842 | Thomas Cushing Aylwin | Thomas Cushing Aylwin | Sought re-election upon appointment as Solicitor General for Lower Canada |
| Hastings | October 17, 1842 | Robert Baldwin | No Return due to riots | Sought re-election upon appointment as Attorney General for Upper Canada |
| 3rd Riding of York | October 15, 1842 | James Edward Small | James Edward Small | Sought re-election upon appointment as Solicitor General for Upper Canada |
| 4th Riding of York | October 8, 1842 | Louis Hippolyte LaFontaine | Louis Hippolyte LaFontaine | Sought re-election upon appointment as Attorney General for Lower Canada |
| London | September 28, 1842 | Hamilton Hartley Killaly | Hamilton Hartley Killaly | Sought re-election upon appointment as Chairman of the Board of Works |
| Ottawa County | August 17, 1842 | Charles Dewey Day | Denis-Benjamin Papineau | Appointed a judge |
| Leinster | August 8, 1842 | Jean-Moïse Raymond | Jacob De Witt | Appointed registrar |
| Saint-Maurice | July 8, 1842 | Joseph-Édouard Turcotte | Joseph-Édouard Turcotte | Sought re-election due to holding two government offices |
| Rouville | July 7, 1842 | Melchior-Alphonse d'Irumberry de Salaberry | William Walker | Appointed registrar |
| Oxford | July 6, 1842 | Francis Hincks | Francis Hincks | Sought re-election upon appointment as Inspector General |
| Bellechasse | June 6, 1842 | Augustin-Guillaume Ruel | Abraham Turgeon | Appointed registrar |
| Deux Montagnes | April 18, 1842 | Colin Robertson | Charles John Forbes | Death |
| Nicolet | February 15, 1842 | Augustin-Norbert Morin | Louis-Michel Viger | Resignation to be appointed a judge |
| Verchères | December 28, 1841 | Henri Desrivières | James Leslie | Resignation to provide a seat for Leslie |
| 4th Riding of York | September 21, 1841 | Robert Baldwin | Louis Hippolyte LaFontaine | Chose to sit for Hastings |
| Middlesex | July 10, 1841 | Thomas Parke | Thomas Parke | Sought re-election upon appointment as Surveyor General |
| Kingston | July 1, 1841 | Anthony Manahan | Samuel Harrison | Appointed Collector of Customs for Toronto |
The Legislative Council became an elective body in 1856. By-elections were held to fill vacancies. In 1857 Legislative Councillors appointed to office were now required to seek re-election at Ministerial by-elections.
| By-election | Date | Incumbent | Winner | Cause |
|---|---|---|---|---|
| Brock | January 25, 1866 | Adam Johnston Fergusson Blair | Adam Johnston Fergusson Blair | Sought re-election upon appointment as President of the Executive Council |
| Stadacona | September 19, 1864 | François Baby | Jean-Élie Gingras | Death |
| La Durantaye | June 25, 1864 | François-Xavier Lemieux | Joseph-Noël Bossé | Death |
| Cataraqui | April 30, 1864 | Alexander Campbell | Alexander Campbell | Sought re-election upon appointment as Commissioner of Crown Lands |
| Rougemont | January 8, 1864 | Louis-Antoine Dessaulles | William Henry Chaffers | Appointed Clerk of the Crown and Peace |
| St. Clair | September 19, 1863 | John Wilson | Alexander Vidal | Appointed a judge |
| Newcastle | September 17, 1863 | Andrew Jeffrey | Asa Burnham | Death |
| Trent | July 21, 1863 | Sidney Smith | Billa Flint | Resignation to contest the 1863 general election |
| Victoria | June 19, 1863 | Luther Hamilton Holton | Thomas Ryan | Vacated seat on appointment as Minister of Finance and contested the 1863 general election |
| Grandville | June 5, 1863 | Luc Letellier de St-Just | Luc Letellier de St-Just | Sought re-election upon appointment as Minister of Agriculture |
| Rigaud | June 3, 1863 | Robert Unwin Harwood | Eustache Prud'homme | Death |
| St. Clair | May 16, 1863 | Malcolm Cameron | John Wilson | Appointed Queen's Printer |
| Wellington | May 8, 1863 | Hollis Smith | John Sewell Sanborn | Death |
| De Lanaudière | April 6, 1863 | Alexandre Bareil, dit Lajoie | Louis Auguste Olivier | Death |
| Brock | March 28, 1863 | Adam Johnston Fergusson Blair | Adam Johnston Fergusson Blair | Sought re-election upon appointment as Receiver General |
| De Lorimier | February 26, 1863 | Jacques-Olivier Bureau | Jacques-Olivier Bureau | Sought re-election upon appointment as Provincial Secretary and Registrar |
| Western | September 18, 1862 | Allan MacNab | Walter McCrea | Death |
| Niagara | September 4, 1862 | William Hamilton Merritt | James Currie | Death |
| Gulf | June 23, 1862 | Ulric-Joseph Tessier | Ulric-Joseph Tessier | Sought re-election upon appointment as Commissioner of Public Works |
| Saugeen | May 9, 1862 | James Patton | John McMurrich | Sought re-election upon appointment as Solicitor General for Upper Canada |
| Rideau | April 21, 1862 | Philip Michael Matthew Scott VanKoughnet | James Skead | Appointed a judge |
| Trent | September 28, 1861 | Edmund Murney | Sidney Smith | Death |
| Stadacona | June 17, 1861 | Pierre-Gabriel Huot | François Baby | Void Election |
| Montarville | June 17, 1861 | Alexandre-Édouard Kierzkowski | Louis Lacoste | Void Election |
| Western | November 24, 1860 | John Prince | Allan MacNab | Appointed a judge |
| Sorel | June 18, 1860 | Jean-Baptiste Guèvremont | Jean-Baptiste Guèvremont | Void Election |