St. Mary's A.F.C. was formed in 1948 as a single youth team based in Gurranabraher, taking their name from the Cathedral of St Mary and St Anne. In 1948–49 the club entered a team in the Munster Youth League. The following season, 1949–50, saw the formation of schoolboy and junior teams and the club also entered the Munster Junior League. 1949–50 also saw the club win its first trophy, the Munster Youth Cup, after defeating Clonmel Town 2–1 in the final at Turners Cross.

Junior level
In 1955–56 St. Mary's joined the Cork Athletic Union League and in their first season won the league's main league cup, the AOH Cup, after defeating Fermoy 4–2 in the final after extra time.[5][6] During the late 1960s, 1970s and early 1980s, St. Mary's developed into one of the Cork AUL's strongest teams, winning the league title on six occasions and winning the AOH Cup six times.[7][8][9][10] In 1971–72 they also reached the final of the FAI Junior Cup but lost to Talbot (Dublin).

Intermediate level
In 1986–87 St. Mary's joined the Munster Senior League and in 1988–89, after winning the MSL second level division, they were promoted to the Premier Division.[10] During the mid-1980s St. Mary's also moved away from their original Cork city base to their current home at Kilcully Park.

1950-1951

Newcomers St. Marys make a firm impact on the Munster Junior League scene by winning the MJC, the Tyler Cup and the Munster Junior League undefeated.  Scenes of joy near Shandon – Mikey Dunne is offered a trial by Arsenal and declines.

1951-1952

Winners of the Munster Minor League and Shield Runners-Up.  Sean Burns, John Cullen and Jerry Geaney emerge from a class of excellence to play League Of Ireland soccer.

1952-1953

Winners of the Cork City Minor Challenge Cup and Runners-up in the Minor League, Shield & Cup

1953-1954

Winners of the Foley Cup and City Junior Challenge Cup.  Runners-up in The Jimmy Daly Memorial Cup

1954-1955

Winners of the City Junior Challenge Cup for the second consecutive year.

1955-1956

Having spent the first six years of their life in the Munster Junior League, St. Mary’s move residence to the Cork City & County Athletic Union League with the help of Nat Ross. Their inaugural season was blessed with the winning of the League’s most sought after jewel, The A.O.H. Cup

1956-1957

A lone trophy occupies the sideboard, the Frist Division Shield is won.

1957-1958

St. Mary’s win the Munster Junior Cup for the second time after a three match marathon Cup-Final.  A fractured leg ruled Charlie Browne out of the final victory, Morgan Virgo scores from the spot at the Markets Field, O’Connell’s goal seals Cup victory at the Mardyke.

1958-1959

Runners-Up in the minor League to Tower Rovers, Runners-Up in the Timothy Jim O’Keefe Cup to Ringmahon Rangers. Winners of the Junior Reserve League; St Mary’s Reserves 4 – Rockmount Reserves 2.  After a rousing decider on Wednesday 29th May 1951

1959-1965

St. Mary’s found themselves wandering aimlessly on barren soil, the club needed and experienced figure to turn its’ fortunes around, to restructure and inspire. Help was about to arrive from an unexpected source.  St. Mary’s win the Jimmy Daly Memorial Cup with goals by Jerry Geaney and Felix Manning v Bridewell.

1965-1966

Paddy Cambridge supplied the Midas touch which put a halt to St. Mary’s downward plunge with the signing of the non-pareil of centre-halfs John Coughlan and the ever reliable Mick O’Keeffe. The two former Cork Celtic defenders transformed a mediocre side into a mean machine. First Division League Championship, A.O.H. Cup, double Shield and Saxone Cup and Tournament victories were recorded.  The big disappointment to what would have been the ending of a perfect season was the losing of the Munster Junior Cup Final  to old Limerick friends Caledonians by 2 goals to zero at Turners Cross.

1966-1967

That which was lost in 66′ was captured in 67′ with a victory in the Munster Junior Cup Final against another Limerick side, Geraldines by 3 goals to 1.  St. Mary’s had little success in local competitions, the fist Division Shield was the lone partner on the sideboard with the Provincial Trophy.

1967-1968

St. Mary’s and Everton again contested the Saxone Cup Final, Saints coming good again as they did in 66′.

1968-1969

Aggression and consistency were absent friends this season with little to show at the end.

1970-1971
St.Mary’s fought a terrific League compaign with Middle Parish reps Wembley, with the Saints eventually taking the Premier league Pennent. The Saxone and President’s Cups came back to their old home in Gurranabraher and the Saint’s second string made their contribution to the silver swag by winning the Second Division Shield. St. Michaels of Tipperary nicked the A.O.H Cup while the Saints were having forty winks.

1971-1972
Crosshaven with goal hungry Buzz O’Connell leading the seasider’s attack captured the season’s curtain raiser, “The Premier Shield”, St. Mary’s Runners-Up ST. Mary’s turned the tables on the Crosshaven by taking their fourth Munster Junior Cup in a Cork A.U.L Derby Final.

1972-1973
Premier Shield and A.O.H. Cup triumphs against Wembley and Castleview respectively.

1973-1974
Premier Shield winners over Wembley. The Hawk swoops with his Tipperary Saints to clinch the Premier Leaque Championship, St. Mary’s pick up Runners-Up spot.

1974-1975
St. Mary’s are double achievers. Fourth A. O.H. Cup Victory. Killeagh Utd bow to superior Saints.
St Mary’s pip Castleview for Premier League Title.

1975-1976

Cork City’s oldest club Rockmount F.C. win their first Premier League Honours by beating St. Mary’s to the finishing line. Rockmount also overcome St. Mary’s in the Cork area of the F.A.I. Junior Challenge Cup And a dismal ending to the season for St. Mary’s with the loss of the A.O.H. Cup to Castleview

1976-1977
Premier League Runners-Up to Castleview. St. Mary’s record a fifth A.O.H. Cup over Avondale Utd by 2-0 Reserve side St. Mary’s Utd win Saxone Cup over 4th Batallion.

1977-1978
St. Mary’s win youths Division One over Springfield. Murphy Cup won victory over Kilreen Celtic. St. Mary’s advance in Cork area over Midleton_League Pennant flutters over Crofton Celtic’s H.Q. with Saints as Runners-Up.

1978-1979
A season of discontent. Organised protest marches to highlight the shortage of soccer pitches. St. Mary’s missing from the honours parade this season but the kids keep the flag flying St. Mary’s U-13 Champions win 4-1 over Everton, E Browne, JMcHale, MO’Calaghan & Daclan Daly hit the target. It is of interest to note that Everton’s goal was scored by Noel O’Sullivan from an excellently taken corner by the one and only Denis Irwin. St. Mary’s AFC take this opportunity of wishing Denis all the best in his life at home, and every success in his football career for his club Manchestor United and his country Republic of Ireland.

1979-1980
St. Mary’s youths lose out to Rockmount and Tramore Athletic in the Murphy and Munster Youths Cups separately.

1980-1981

Casement Celtic make their mark this season by taking Premier  league Honours with St. Mary’s in the Runners-Up spot. Murphy Cup triump over Tramore Athletic.  St. Mary’s carve their name on the A.O.H. Cup for a record sixth time with Barry Cup Finalists.

1981-1982

Winners of the Premier League.

Winners of the Coca-Cola Cup over Sprinfield.

St. Mary’s lose St. Michael’s Cup to Ballincollig.

1982-1983

Premier League Champions over Tramore Athletic

Murphy Cup winners over Ballinlough Rovers by 2-1.  Twomey and Hayes were Saints goalscorers.

1983-1984

St Mary’s fail to figure in the honours list this season

1984-1985

Temple United record their first Premier League Championship Title win.  St. Mary’s win St. Michael’s Cup v Douglas Hall and overcome Temple United in Cork area F.A.I Junior Cup.

Coca Cola Cup for Springfield v St. Mary’s.

1985-1986

Premier League Champions v Douglas Hall.

St. Mary’s youths capture Munster Youths Cup v St. Michael’s (Tipperary) by 4-2

1986-1987

St. Mary’s are Winners Youth Division One v Ballincollig.

Ger Long is acclaimed Player of the year in The Cork Schoolboy’s League.  St. Mary’s are admitted to the Munster Senior League .

Keane Cup Finalists.

1987-1988

St. Mary’s lose Youths Division One title to Tramore Athletic but win the Coca Cola Cup v Carrigaline Utd.  St. Mary’s win Division Two.

Beamish Cup Victors. Qualifiers F.A.I. Cup.

Winners Pop Keller Cup

McFaul Cup Winners.

1988-1989

St. Mary’s win their first Senior Crown. First Division Champions and promotion  to the Premier Division.  Beamish Cup and Pop Keller Cup victories see the Saints scale new heights in their third season of Senior Soccer. McFaul Cup victory.

1989-1990

Cobh Ramblers take the Youths Cup with a win over St Mary’s.  St. Mary’s Seniors take The Beamish Cup with a 1-0 win over Everton.

1991-1992

Midleton win Super Cup Junior Section of The Munster Senior League

1992-1993

Avondale United are Premier League Champions. St. Mary’s win James O’Connell Memorial Cup with a Thomas Long hat-trick and the ace marksman’s lone strike torpedoes Avondale Utd in the Keane Cup Final.

A great season for the Saints.

1993-1994

St. Mary’s retain The Keane Cup. Goal bandit Thomas Long puts Everton to the sword. Beamish Cup Semi Final defeat for St. Mary’s

Cork City 3: St Mary’s 0

Everton are Premier Champions.

1994-1995

St. Mary’s Mick Cummins (2) and Trevor Bennett (1) pen secures Beamish Cup Final spot in a 3-0 victory over Cork City.   Beamish Cup Final victory for Avondale United.  Thomas Long’s strike sinks his old teammates.

1995-1996

Casement Celtic advanced to The O’Connell Final with a two goal blast by Goulding, St. Mary’s lacked bite and flair.  Premier League flag for College Corinthians.

1996-1997

Alan Moore shines in third Keane Cup Final win for St. Mary’s. The performance wins him The Man of the Match award

1997-1998

St. Mary’s hit lowest point of their twelve-year existence in The Munster Senior League.

Successful fight for Premiership survival in a 2-0 win over Everton.

1998-1999

New Senior Manager appointed. Martin Heffernan puts his new charges through their paces. Great expectations forecast.