| School | Address | City | Province | Postal Code |
| O'Donel High School | 50 Ruth Avenue | St. John's | NF | A1N 2H5 |
| O'Neill Collegiate and Vocational Institute | 301 Simcoe Street North | Oshawa | ON | L1G 4T2 |
| Oak Bay Secondary School | 2151 Cranmore Road | Victoria | BC | V8R 1Z2 |
| Oak Park High School | 820 Charleswood Road | Winnipeg | MB | R3R 1K6 |
| Oakridge Secondary School | 1040 Oxford Street | London | ON | N6H 1V4 |
| Oakville Trafalgar High School | 1460 Devon Road | Oakville | ON | L6J 3L6 |
| Okanagan Mission Secondary School | 4544 Gordon Drive | Kelowna | BC | V1W 1T4 |
| Orangeville District Secondary School | 22 Faulkner Street | Orangeville | ON | L9W 2G7 |
| Oromocto High School | 25 MacKenzie Avenue | Oromocto | NB | E2V 1K4 |
| Osgoode Township High School | 2800 8th Line Road | Metcalfe | ON | K0A 2P0 |
| Our Lady of Mount Carmel | 3700 Trelawny Circle | Mississauga | ON | L5N 5J7 |
| Oxbow Prairie Heights High School | 515 Wylie | Oxbow | SK | S0C 2B0 |