| By-election | Date | Incumbent | Party | Winner | Party | Cause | Retained |
|---|
| Stanstead | January 22, 1908 | Henry Lovell | | Liberal | Charles Henry Lovell | | Liberal | Death | Yes |
| Huron South | January 22, 1908 | Benjamin B. Gunn | | Conservative | Murdo Young McLean | | Liberal | Death | No |
| Nicolet | December 30, 1907 | Charles Ramsay Devlin | | Liberal | Gustave-Adolphe-Narcisse Turcotte | | Liberal | Resignation upon appointment to the provincial cabinet of Quebec | Yes |
| City of Ottawa | December 23, 1907 | Napoléon Antoine Belcourt | | Liberal | William H. Hutchison | | Liberal | Called to the Senate | Yes |
| Labelle | December 23, 1907 | Henri Bourassa | | Liberal | Charles Beautron Major | | Liberal | Resignation to enter provincial politics | Yes |
| York Centre | December 23, 1907 | Archibald Campbell | | Liberal | Peter Douglas McLean | | Liberal | Called to the Senate | Yes |
| Colchester | November 28, 1907 | Frederick Andrew Laurence | | Liberal | John Stanfield | | Conservative | Appointed a judge | No |
| London | October 29, 1907 | C. S. Hyman | | Liberal | Thomas Beattie | | Conservative | Resignation | No |
| Northumberland East | October 29, 1907 | Edward Cochrane | | Conservative | Charles Lewis Owen | | Conservative | Death | Yes |
| Wellington North | October 29, 1907 | Thomas Martin | | Liberal | Alexander Munro Martin | | Liberal | Death | Yes |
| Brockville | September 18, 1907 | Daniel Derbyshire | | Liberal | George Perry Graham | | Liberal | Called to the Senate | Yes |
| City and County of St. John | September 18, 1907 | Alfred Augustus Stockton | | Conservative | William Pugsley | | Liberal | Death | No |
| Richelieu | March 7, 1907 | Arthur-Aimé Bruneau | | Liberal | Adélard Lanctôt | | Liberal | Appointed a judge of the Superior Court of Quebec | Yes |
| L'Assomption | March 7, 1907 | Romuald-Charlemagne Laurier | | Liberal | Ruben Charles Laurier | | Liberal | Death | Yes |
| Victoria | March 5, 1907 | John Costigan | | Liberal | Pius Michaud | | Liberal | Called to the Senate | Yes |
| Three Rivers and St. Maurice | February 28, 1907 | Jacques Bureau | | Liberal | Jacques Bureau | | Liberal | Recontested upon appointment as Solicitor General | Yes |
| Nicolet | December 29, 1906 | Rodolphe Lemieux | | Liberal | Charles Ramsay Devlin | | Liberal | Chose to sit forGaspé | Yes |
| St. Ann | November 21, 1906 | Daniel Gallery | | Liberal | Joseph Charles Walsh | | Liberal | Election declared void | Yes |
| St. Mary | November 21, 1906 | Camille Piché | | Liberal | Médéric Martin | | Liberal | Appointed Police Magistrate in Montreal. | Yes |
| Shelburne and Queen's | October 31, 1906 | William Stevens Fielding | | Liberal | William Stevens Fielding | | Liberal | Election declared void | Yes |
| Bruce North | October 30, 1906 | Leonard Thomas Bland | | Liberal-Conservative | John Tolmie | | Liberal | Death | No |
| Quebec County | October 23, 1906 | Charles Fitzpatrick | | Liberal | Lorenzo Robitaille | | Independent Liberal | AppointedChief Justice of Canada | No |
| St. Johns—Iberville | October 16, 1906 | Louis Philippe Demers | | Liberal | Marie Joseph Demers | | Liberal | Appointed Puisne Judge of the Superior Court of Quebec | Yes |
| Elgin East | October 14, 1906 | Andrew B. Ingram | | Liberal-Conservative | David Marshall | | Conservative | Appointed Vice Chairman of the Ontario Railway and Municipal Commission | Yes |
| Renfrew North | October 9, 1906 | Peter White | | Conservative | Gerald Verner White | | Conservative | Death | Yes |
| Strathcona | April 5, 1906 | Peter Talbot | | Liberal | Wilbert McIntyre | | Liberal | Called to the Senate | Yes |
| Cape Breton North and Victoria | March 14, 1906 | Daniel Duncan McKenzie | | Liberal | Alexander Charles Ross | | Liberal | Appointed a judge | Yes |
| Victoria City | March 6, 1906 | George Riley | | Liberal | William Templeman | | Liberal | Resignation to provide a seat for Templeman | Yes |
| Maisonneuve | February 23, 1906 | Raymond Préfontaine | | Liberal | Alphonse Verville | | Labour | Death | No |
| Assiniboia West | February 6, 1906 | Thomas Walter Scott | | Liberal | William Erskine Knowles | | Liberal | Resignation to enter provincial politics in Saskatchewan | Yes |
| Saskatchewan | February 6, 1906 | John Henderson Lamont | | Liberal | George Ewan McCraney | | Liberal | Resignation to enter provincial politics in Saskatchewan | Yes |
| Town of Sherbrooke | February 6, 1906 | Arthur Norreys Worthington | | Conservative | Arthur Norreys Worthington | | Conservative | Election declared void | Yes |
| Compton | January 4, 1906 | Aylmer Byron Hunt | | Liberal | Aylmer Byron Hunt | | Liberal | Election declared void | Yes |
| York North | November 22, 1905 | William Mulock | | Liberal | Allen Bristol Aylesworth | | Liberal | Appointed a judge | Yes |
| Antigonish | November 22, 1905 | Colin McIsaac | | Liberal | William Chisholm | | Liberal | Appointed a Railway Commissioner | Yes |
| Lambton West | November 22, 1905 | Thomas George Johnston | | Liberal | Frederick Forsyth Pardee | | Liberal | Death | Yes |
| Wentworth | November 22, 1905 | E. D. Smith | | Conservative | E. D. Smith | | Conservative | Election declared void | Yes |
| London | June 13, 1905 | C. S. Hyman | | Liberal | C. S. Hyman | | Liberal | Recontested upon appointment as Minister of Public Works | Yes |
| Oxford North | June 13, 1905 | James Sutherland | | Liberal | George Smith | | Liberal | Death | Yes |
| Lévis | June 6, 1905 | Louis Julien Demers | | Liberal | Louis Auguste Carrier | | Liberal | Death | Yes |
| Edmonton | April 25, 1905 | Frank Oliver | | Liberal | Frank Oliver | | Liberal | Recontested upon appointment as Minister of the Interior. | Yes |
| Toronto Centre | April 11, 1905 | Edward Frederick Clarke | | Conservative | Edmund James Bristol | | Conservative | Death | Yes |
| Wright | February 13, 1905 | Wilfrid Laurier | | Liberal | Emmanuel Berchmans Devlin | | Liberal | Chose to sit forQuebec East | Yes |
| Carleton | February 4, 1905 | Edward Kidd | | Conservative | Robert L. Borden | | Conservative | Resignation to provide a seat for Borden | Yes |
| Quebec-Centre | January 19, 1905 | Arthur Cyrille Albert Malouin | | Liberal | Arthur Lachance | | Liberal | Appointed a judge of the Superior Court of Quebec | Yes |