This is a list of OHA standings and season-by-season summaries of the Ontario Hockey Association's Junior A division from 1933 to 1972, and its Tier I division from 1972 to 1974.
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1933–34.
The Toronto St. Michael's Majors won the J. Ross Robertson Cup, defeating the Stratford Midgets 2 games to 0.
Group Semi-finals
London beat Woodstock 3 goals to 2.
(1-2, 2-0)
Kitchener Empires beat Galt Terrier Pups 5 goals to 4.
(1-3, 4-1)
Group Finals
Toronto Young Rangers beat Parkdale Canoe Club 13 goals to 3.
(4-2, 9-1)
Toronto St. Michael's Majors beat Oshawa Majors 2 wins to none, 1 tie.
(3-3, 8-2, 10-4)
Windsor Wanderers beat London 8 goals to 5.
(2-0, 6-5)
Stratford Midgets beat Kitchener Empires 11 goals to 9.
(5-4, 6-5)
Semi-final
Stratford Midgets beat Windsor Wanderers 25 goals to 3.
(6-2, 19-1)
Toronto St. Michael's Majors beat Toronto Young Rangers 13 goals to 3.
(6-0, 7-3)
Robertson Cup Finals
Toronto St. Michael's Majors beat Stratford Midgets 2 wins to none.
(7-0, 4-2)
OHA Grand Championship
Toronto St. Michael's Majors beat St. Michael's Buzzers (Jr. B) by default.
(12-3, default)
1934–35.
The Kitchener Greenshirts won the J. Ross Robertson Cup by default over the Oshawa Majors.
Group Semi-finals
Toronto Lions beat Toronto St. Michael's Majors 8 goals to 7.
(0-3, 5-2, 3-2)
Stratford Midgets beat Galt Terrier Pups 11 goals to 2.
(6-1, 5-1)
Group Finals
Oshawa Majors beat Toronto Lions 2 wins to none.
(10-2, 10-3)
Toronto Young Rangers beat Parkdale Canoe Club 13 goals to 4.
(4-3, 9-1)
Kitchener Greenshirts beat Stratford Midgets 2 wins to none, 1 tie.
(2-2, 6-1, 5-4)
Semi-final
Kitchener Greenshirts beat Windsor Wanderers 10 goals to 4.
(4-1, 6-3)
Oshawa Majors beat Toronto Young Rangers 10 goals to 8.
(3-4, 4-3, 3-1)
Robertson Cup Final
Results thrown out due to Oshawa using illegal player.
Oshawa won Game 1 4-1, Kitchener won Game 2 4-3, then it was discovered that Oshawa used an illegal player (Bill Bagnall). Due to time constraints a third game was then played to determine entry into the Memorial Cup playdowns, but not the winner of the winner of the Robertson Cup -- to be determined later.
Quarter-final
Toronto Lions 9 - Toronto Young Rangers 8 (OT)
Semi-final
Kitchener Greenshirts 7 - Toronto Lions 5
Final
Kitchener Greenshirts beat Oshawa Majors by default
Oshawa refused to play, claiming they had already won the championship. The Ontario Hockey Association disagreed and awarded the title to Kitchener.
1935–36.
The West Toronto Nationals won the J. Ross Robertson Cup, defeating the Kitchener Greenshirts 2 games to 0.
Group Semi-finals
Toronto St. Michael's Majors beat Toronto Native Sons 9 goals to 6.
(3-4, 6-2)
West Toronto Nationals beat Toronto Young Rangers 6 goals to 3.
(5-0, 1-3)
Stratford Midgets beat Niagara Falls 12 goals to 9.
(6-5, 6-4)
Group Finals
West Toronto Nationals beat Toronto St. Michael's Majors 3 wins to none.
(1-0, 6-1, 6-5)
Kitchener Greenshirts beat Stratford Midgets 5 goals to 1.
(2-0, 3-1)
Semi-final
West Toronto Nationals beat Oshawa Majors 2 wins to none.
(5-2, 6-2)
Robertson Cup Final
West Toronto Nationals beat Kitchener Greenshirts 2 wins to none.
(3-2, 6-1)
1936–37.
The Toronto St. Michael's Majors won the J. Ross Robertson Cup, defeating the Stratford Midgets 3 games to 2.
Group Semi-finals
Toronto St. Michael's Majors beat Toronto Young Rangers 2 wins to 1.
(7-4, 3-4, 12-4)
Toronto British Consols beat Oshawa Generals 2 wins to none.
(4-1, 5-5, 7-4)
Group Finals
Toronto St. Michael's Majors beat Toronto British Consols 3 wins to none.
(4-3, 5-3, 3-1)
Stratford Midgets beat Kitchener Greenshirts 2 wins to none.
(5-3, 4-1)
Robertson Cup
Toronto St. Michael's Majors beat Stratford Midgets 3 wins to 2.
(6-2, 4-7, 4-5, 6-5, 8-3)
1937–38.
The Oshawa Generals won the J. Ross Robertson Cup, defeating the Guelph Indians 3 games to 0.
1938–39.
The Oshawa Generals won the J. Ross Robertson Cup, defeating the Toronto Native Sons 3 games to 0.
1939–40.
The league drops its divisions. The Toronto St. Michael's Majors and the Toronto Lions drop out of the league. The University of Toronto Varsity Blues drop out of the league mid-season. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Toronto Marlboros 3 games to 2.
1940–41.
Toronto Young Rangers are renamed Toronto Bowles Rangers. Guelph Indians become Guelph Biltmore Mad Hatters. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Toronto Marlboros 4 games to 3.
1941–42.
The Toronto Bowles Rangers revert to being the Toronto Young Rangers. The Toronto St. Michael's Majors rejoin the league. The Brantford Lions join the league. The Toronto Native Sons drop out halfway through the season, and declare all their games forfeit. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Guelph Biltmore Mad Hatters 3 games to 2.
1942–43.
The Hamilton Whizzers and the Stratford Kroehlers join the league. The Guelph Biltmore Mad Hatters drop out of the league. The Toronto Young Rangers drop out of the league. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Brantford Lions 4 games to 1.
1943–44.
The OHA splits into two groups when four teams join the league; the Galt Canadians, St. Catharines Falcons, Port Colborne Recreationists, and Toronto Young Rangers. The Hamilton Whizzers, become Hamilton Majors. The Oshawa Generals won the J. Ross Robertson Cup, defeating the Toronto St. Michael's Majors 4 games to 1. Oshawa's Ken Smith won the scoring title with 53 goals and 26 assists for 79 points, followed by teammates Bob Love (75) and Bill Ezinicki (63).
1944–45.
The OHA groups are dissolved when the Brantford Lions, Stratford Kroehlers and Hamilton Majors drop out of league. The Galt Canadians become the Galt Red Wings. The Port Colborne Recreationists drop out of the league mid-season. The inaugural Red Tilson Trophy is awarded to Doug McMurdy, as the most outstanding player in the OHA; Albert "Red" Tilson, a recent Oshawa Generals player and the OHA scoring champion of 1942–43, was killed in World War II action just as the 1944–45 OHA season was starting. The Toronto St. Michael's Majors won the J. Ross Robertson Cup, defeating the Galt Red Wings 4 games to 0.
"(*) folded mid-season"
1945–46.
The Barrie Flyers and the Hamilton Lloyds join the league. The inaugural Eddie Powers Memorial Trophy is awarded for the top scorer in the league to Tod Sloan. He was also awarded the Red Tilson Trophy as the most outstanding player. The Toronto St. Michael's Majors won the J. Ross Robertson Cup, defeating the Oshawa Generals 4 games to 2.
1946–47.
The Hamilton Lloyds become Hamilton Szabos. The Windsor Spitfires join the league, and the Stratford Kroehlers rejoin the league. The Toronto St. Michael's Majors won the J. Ross Robertson Cup, defeating the Galt Red Wings 4 games to 0.
1947–48.
Hamilton drops out of the league. The Guelph Biltmore Mad Hatters join the league. The Galt Red Wings become the Galt Rockets. The St. Catharines Falcons become the St. Catharines Teepees. The Barrie Flyers won the J. Ross Robertson Cup, defeating the Windsor Spitfires 4 games to 2.
1948–49.
Toronto Young Rangers drop out of the league. The Barrie Flyers won the J. Ross Robertson Cup.
1949–50.
The Galt Rockets become the Galt Black Hawks. The Guelph Biltmore Mad Hatters won the J. Ross Robertson Cup.
1950–51.
The Waterloo Hurricanes join the league. The Barrie Flyers won the J. Ross Robertson Cup.
1951–52.
The Kitchener Greenshirts join the league. The Stratford Kroehlers drop out of the league. The Guelph Biltmore Mad Hatters won the J. Ross Robertson Cup.
1952–53.
The Waterloo Hurricanes drop out of the league. The Barrie Flyers won the J. Ross Robertson Cup.
1953–54.
The Windsor Spitfires become the Hamilton Tiger Cubs. The Oshawa Generals drop out of the league, after a fire destroys the Hambly Arena. The St. Catharines Teepees won the J. Ross Robertson Cup.
1954–55.
The Kitchener Greenshirts become the Kitchener Canucks. The Toronto Marlboros won the J. Ross Robertson Cup.
1955–56.
The Galt Black Hawks drop out of the league. The Toronto Marlboros won the J. Ross Robertson Cup.
1956–57.
The Kitchener Canucks become the Peterborough TPT Petes. The Guelph Biltmore Mad Hatters won the J. Ross Robertson Cup.
Each team played each other team eight times, as well as playing four games against the Hull-Ottawa Canadiens.
1957–58.
Each team played each other team eight times, as well as playing four games against the Hull-Ottawa Canadiens (although the final game between Barrie and Hull-Ottawa was cancelled).
"The Hamilton Spectator" donated a trophy awarded annually to the team that finished first overall in the regular season. The St. Catharines Teepees won the first Hamilton Spectator Trophy. The Toronto Marlboros won the J. Ross Robertson Cup.
1958–59.
The St. Catharines Teepees repeated their first overall finish in the regular season, winning the Hamilton Spectator Trophy. The Peterborough TPT Petes won the J. Ross Robertson Cup.
1959–60.
The Toronto Marlboros finished first overall in the regular season, winning the Hamilton Spectator Trophy. The St. Catharines Teepees won the J. Ross Robertson Cup.
1960–61.
The Guelph Biltmore Mad Hatters become the Guelph Royals. The Barrie Flyers become the Niagara Falls Flyers. The Hamilton Tiger Cubs become the Hamilton Red Wings. The OHA inaugurates the Max Kaminsky Trophy for the league's most gentlemanly player. The Guelph Royals finished first overall in the regular season, winning the Hamilton Spectator Trophy. The Toronto St. Michael's Majors won the J. Ross Robertson Cup.
1961–62.
The Montreal Jr. Canadiens join the OHA from the Quebec Junior Hockey League. The Metro Junior A League starts. Its teams will be the St. Michael's Majors, Toronto Marlboros, Brampton 7Ups, Unionville Seaforths and Whitby Mohawks. The Montreal Junior Canadiens finished first overall in the regular season, winning the Hamilton Spectator Trophy. The Hamilton Red Wings won the J. Ross Robertson Cup.
1962–63.
The Oshawa Generals join the Metro Junior League. The Toronto St. Michael's Majors become the Toronto Neil McNeil Maroons. The Unionville Seaforths become Toronto Knob Hill Farms. The Whitby Mohawks become the Whitby Dunlops. The St. Catharines Teepees become the St. Catharines Black Hawks. The Niagara Falls Flyers finished first overall in the regular season, winning the Hamilton Spectator Trophy, and won the J. Ross Robertson Cup in the playoffs.
1963–64.
The Metro Junior League disbands. The Toronto Marlboros rejoin the OHA, as do the Oshawa Generals although they play their first season in Bowmanville. The other teams in the Metro Junior League cease operations. The Guelph Royals become the Kitchener Rangers. The Toronto Marlboros, now the only team representing Toronto in an OHA Junior A season in the league's history, finished first overall in the regular season, winning the Hamilton Spectator Trophy, and won the J. Ross Robertson Cup in the playoffs.
1964–65.
The Niagara Falls Flyers finished first overall in the regular season, winning the Hamilton Spectator Trophy, and won the J. Ross Robertson Cup in the playoffs.
1965–66.
The London Nationals are granted a franchise, moving their Junior B team of the same name to Ingersoll. The Peterborough Petes finished first overall in the regular season, winning the Hamilton Spectator Trophy. The Oshawa Generals won the J. Ross Robertson Cup.
1966–67.
The Kitchener Rangers finished first overall in the regular season, winning the Hamilton Spectator Trophy. The Toronto Marlboros won the J. Ross Robertson Cup.
1967–68.
The Ottawa 67's are granted a franchise. The Kitchener Rangers finished first overall in the regular season, winning the Hamilton Spectator Trophy. The Niagara Falls Flyers won the J. Ross Robertson Cup.
1968–69.
The London Nationals become the London Knights. The Montreal Junior Canadiens finished first overall in the regular season, winning the Hamilton Spectator Trophy, and won the J. Ross Robertson Cup in the playoffs.
1969–70.
The Max Kaminsky Trophy is rededicated, now awarded to the most outstanding defenceman in the league. The Montreal Junior Canadiens finished first overall in the regular season, winning the Hamilton Spectator Trophy, and won the J. Ross Robertson Cup in the playoffs.
1970–71.
OHA president Tubby Schmalz was concerned with the level of physical play during the season, and personally interviewed four players to dissuade them from further on-ice misconduct. He submitted recommendations to the 1971 Canadian Amateur Hockey Association general meeting on behalf of the OHA to reduce the curvature of the hockey stick to one half inch for player safety. He also suggest to revert to the rectangular goal crease from the recent change to a semi-circle, since some rinks in his league were used by professional teams who used the old rules for the goal crease. Schmalz wanted to see consistency the application of the rules, and raise the standards for the level of instruction given to players. He instituted referee and coach clinics in the OHA, prior to it being mandated at the national level. In 1971, he sought to hire a technical director to conduct coaching and refereeing clinics across the province. 
Schmalz announced that teams from the OHA and the Quebec Major Junior Hockey League would not play against any team from the Western Canada Hockey League (WCHL) for the 1971 Memorial Cup, due to disagreements over travel allowances given to team at the Memorial Cup and the higher number of over-age players