The 20th Canadian Parliament was in session from 6 September 1945, until 30 April 1949.

The membership was set by the 1945 federal election on 11 June 1945, and it changed only somewhat due to resignations and by-elections until it was dissolved prior to the 1949 election.

It was controlled by a Liberal Party minority first under Prime Minister William Lyon Mackenzie King and the 16th Canadian Ministry, and later a majority under Prime Minister Louis St. Laurent and the 17th Canadian Ministry.

The Official Opposition was the newly named Progressive Conservative Party, led first by John Bracken and later by George Drew.

In this parliament, the Co-operative Commonwealth Federation, led by M. J. Coldwell, overtook the Social Credit as third largest party.