The 1920-21 Thunder Bay Junior Playoffs were won by the Fort William YMCA. The 1920-21 Memorial Cup Final was played in Toronto so the Fort William team received a bye until the final round of the 1920-21 Western Canada Memorial Cup Playoffs. They lost to eventual 1920-21 Memorial Cup Champion, the Winnipeg Falcons, 20 goals to 7 (9-3, 11-4), in a two game total goals series. No further information is available on the District playoffs itself.