By-elections to the 13th Canadian Parliament were held to elect members of the House of Commons of Canada between the 1917 federal election and the 1921 federal election. Prime Minister Robert Borden, then Arthur Meighen, led a majority government consisting members collectively known as the Unionist Party, during the 13th Canadian Parliament. The list includes Ministerial by-elections 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.