When the South-Central Junior D league was promoted to Junior C, their league champion competed for the Clarence Schmalz Cup, but a second tier champion also competed for the Junior D OHA Cup. In 1974, 1975, 1976, and 1977, the Stayner Siskins competed on behalf of the then Central league for the All-Ontario Junior D title, victorious in 1974 and 1976.
The Georgian Mid-Ontario Junior "C" Hockey League is the result of the 1994 merger of the Mid-Ontario Junior "C" Hockey League and the short-lived Georgian Junior "C" Hockey League. The league began as a Junior "D" league in the early 1970s.
During the 2004-05 season, the GMOHL played an interlocking schedule with the Western Junior C Hockey League. The GMOHL won the series with 44 victories, 32 losses, and 6 ties.
In, May 2010, The OHA confirmed the welcoming of The Caledon Golden Hawks have entered the GMOHL. In March 2012, the GMOHL allowed the Huntsville Otters to join the league after recently retracting from the Ontario Junior Hockey League. With the announcement on April 16, 2015 the league accepted the Collingwood Admirals as the eleventh franchise to the Geogian Bay Mid-Ontario Hockey League. The awarding of the Collingwood franchise was challenged by the Stayner Siskins on the basis that the area did not have enough hockey players to support another franchise. Their appeal was upheld and the expansion Admirals will not participate. The Fergus Devil's announced that they are taking a leave of absence for the 2015-16 season.