By-elections to the 15th Canadian Parliament were held to elect members of the House of Commons of Canada between the 1925 federal election and the 1926 federal election. Initially the Liberal Party of Canada and the Progressive Party of Canada formed a coalition government for the 15th Canadian Parliament, following the King–Byng Affair the Conservative Party of Canada was given a minority government, which dissolved quickly.
The list includes a Ministerial by-election which occurred due to the requirement that Members of Parliament recontest their seats upon being appointed to Cabinet. These by-elections were almost always uncontested. This requirement was abolished in 1931.
| By-election | Date | Incumbent | Party | Winner | Party | Cause | Retained | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Middlesex West | March 29, 1926 | John Campbell Elliott | Liberal | John Campbell Elliott | Liberal | Recontested upon appointment as Minister of Labour | Yes | ||||
| Regina | March 16, 1926 | Francis Nicholson Darke | Liberal | Charles Avery Dunning | Liberal | Resignation to provide a seat for Dunning | Yes | ||||
| Prince Albert | February 15, 1926 | Charles McDonald | Liberal | William Lyon Mackenzie King | Liberal | Resignation to provide a seat for Mackenzie King | Yes | ||||
| Bagot | December 7, 1925 | Joseph Edmond Marcile | Liberal | Georges Dorèze Morin | Liberal | Death | Yes | ||||