The 1984–85 OHL season was the fifth season of the Ontario Hockey League. The Sault Ste. Marie Greyhounds were undefeated in all 33 home games during the regular season. The Brantford Alexanders move back to Hamilton becoming the Hamilton Steelhawks. Fifteen teams each played 66 games. The Sault Ste. Marie Greyhounds won the J. Ross Robertson Cup, defeating the Peterborough Petes.