| Gam Diagnostic Imaging, Oakville - Chemin Trafalgar, L'imagerie diagnostique | Oakville |
| Gam Diagnostic Imaging, Oakville - Hospital Gate, Imagerie diagnostique | Oakville |
| Gamblers Anonymous, Services de soutien aux jeux compulsifs | Vaughan |
| Gendarmerie royale du Canada, Milton - Détachement de Toronto Ouest | Milton |
| Genesis Pharmacy, Services Pharmaceutiques | Halton Hills |
| Genesis Walk-in and Family Clinic | Georgetown |
| Georgetown Pharmacy, Services pharmaceutiques | Halton Hills |
| Glen Eden Pharmacy, Services pharmaceutiques | Milton |
| Glenashton Medical Centre, Cabinet médical familial et clinique sans rendez-vous | Oakville |
| Glenashton Medical Clinic | Oakville |
| Glenashton Pharmacy, Services pharmaceutiques | Oakville |
| GO Transit, GO Transit, Siège social | Toronto |
| Green Communities Canada | Peterborough |
| Greenpeace Canada, Programmes communautaires | Toronto |
| Guardian Pharmacy, Georgetown - Rue Main Sud (Young's Pharmacy and Homecare), Services de pharmacie | Halton Hills |
| Guardian Pharmacy, Oakville - Chemin Lakeshore Est (Lakeshore Drug Mart), Services de pharmacie | Oakville |
| Guardian Pharmacy, Oakville - Chemin Lakeshore Ouest (OSR Pharmacy), Services pharmaceutiques | Oakville |
| Guardian Pharmacy, Oakville - Chemin Trafalgar (Cims Pharmacy), Services pharmaceutiques | Oakville |
| Guardian Pharmacy, Georgetown - Chemin Mountainview Sud (Mountainview Pharmacy), Services pharmaceutiques | Halton Hills |
| Guides du Canada pour les filles, Trouver une unité de guidage | Ontario |
