1970-71 Northern Ontario Senior Playoffs

Independent teams

 * Sault Ste Marie Canadians
 * Thunder Bay Twins

Both teams played in the United States Hockey League.

Final
Best of 5


 * Sault Ste Marie 7 Thunder Bay 4
 * Sault Ste Marie 6 Thunder Bay 5
 * Thunder Bay 4 Sault Ste Marie 1
 * Thunder Bay 7 Sault Ste Marie 4
 * Thunder Bay 6 Sault Ste Marie 1

Thunder Bay Twins beat Sault Ste Marie Canadians 3 games to 2.

Thunder Bay Twins advanced to the 1970-71 Eastern Canada Allan Cup Playoffs.