The St. Mary’s basketball teams compete currently at schools "B" Level basketball in five categories; 1st year boys, 2nd year boys, 3rd year boys, U-16 Boys and U-19 Boys with over 60 players training and playing with the school teams. The school basketball jerseys are black for home matches and yellow for away matches.

The school has made great strides in recent years going from 'C' standard in 2006 all the way to 'A' standard in 2013 and has had several players selected on the Ulster provincial academy squads and also at Northern Ireland level. David Durkan also will be remembered for winning ‘The ESPN Courtside Collection Dunk Contest’ at 17 years old.

All Ireland Schools Under 19B Boys Final. January 2012
St.Mary's CBGS v St.Conleths, Dublin

St Mary’s CBGS 82 (46) (D Durkan 40, P Ferguson 14, L McLarnon 11) St Conleth’s College 67 (31) (S Butler 29, M Ryan 20, K Finn 7)
MVP David Durkan (St Mary’s CBGS)

An irrepressible performance from ‘MVP’ David Durkan inspired St Mary’s CBGS to victory in the final of the All Ireland U-19 B Boys Cup at the expense of Conleth’s College.

A high octane opening to this one saw both sides make some impressive plays. A superb score from David Durkan gave St Mary’s a three point lead before Mark Ryan responded for St Conleth’s 9-8. Ryan was enjoying a blistering start to the game, rebounding superbly for his side in defence, and providing a vital focal point for St Conleth’s attack. It was shaping up to be an intriguing battle between Ryan and St Mary’s Liam McLarnon, a battle that looked likely to shape the outcome of the contest. St Mary’s managed to edge a first quarter high on quality, 19-12.

David Durkan had a huge impact for St Mary’s at the beginning of the second quarter and was instrumental in extending his side’s lead to 11 points. Donal Brady hit two ‘threes’ soon afterwards as St Mary’s surge continued apace. St Conleth’s needed to find an answer quickly as the Mary’s blitz threatened to blow away any hopes they had of success. To their credit St Conleth’s doggedly stuck to their task and were still in contention, but dramatically on the half time buzzer, David Durkan capped a tremendous first half performance with three to give his side a 46-31 lead.

St Mary’s continued to make the running at the beginning of the third quarter, Durkan again to the fore as the challenge of St Conleth’s began to wilt. It was difficult not to feel sympathy for St Conleth’s, who put in a valiant effort in attempting to get back into the game in the final. Alas they were up against an inspired outfit in St Mary’s, who ran out deserved 82-67 winners after an absorbing contest.