As a founding member of the elite PSA competition, Guildford Grammar School involves itself in a full and varied range of inter-school sporting commitments. Organised competition in athletics, badminton, basketball, cricket, cross-country running, football, hockey, rowing, rugby union, soccer, swimming, and tennis, volleyball and water polo is offered to every student in the Senior School.

Many of the competitions date back more than a century and although they are fiercely contested, are played in a spirit of camaraderie and sportsmanship.

In the Preparatory School (primary school), a modified offering of a number of different recreational and sporting activities ensures the students are well trained in the basic skills across a number of codes.

The involvement in both a winter and summer sport is a compulsory requirement of all students at Guildford Grammar School.