| T. B. Radio Communications | Burlington |
| Tai Chi Healthy Bodies Healthy Minds | Milton |
| Take Off Pounds Sensibly, Georgetown Chapter, Weight Related Support Group | Georgetown |
| Take Off Pounds Sensibly, Burlington Chapter, Weight Related Support Group | Burlington |
| Take Off Pounds Sensibly, Milton Chapter, Weight Related Support Group | Milton |
| Talk4Healing, Telephone Helpline and On-line Chat Counselling Services | Thunder Bay |
| Talking for Change | Ontario |
| TechPlace | Burlington |
| TELUS Health MyCare | Toronto Downtown Central |
| Ten Oaks Project, Ottawa | Ottawa |
| The Halton Resource Connection, Child Care Directory and Information Line | Milton |
| The Halton Resource Connection, Resource Library | Milton |
| The Learning Place, Burlington, Pathways to Growth | Burlington |
| Theatre Burlington | Burlington |
| Thomas Alton Medical Clinic, Walk-in Medical Clinic | Burlington |
| Thompson Square Medical Centre | Milton |
| Thompson Walk-In and Medical Clinic | Milton |
| Threads of Life - Association for Workplace Tragedy Family Support | London |
| Threshold School of Building, Ready to Work | Hamilton |
| Thrive Counselling, Burlington Head Office | Burlington |
| Thrive Counselling, Counselling Services | Burlington |
| Thrive Counselling, Milton Office | Milton |
| Thrive Counselling, North Halton Office | Georgetown |
| Thrive Counselling, Oakville Office | Oakville |
| Thrive Counselling, Partner Assault Response Program | Burlington |
| Thrive Counselling, The Safety Zone Program | Halton Region |
| Thrive Counselling, Violence Against Women Program | Halton Region |
| Toronto Abortion Clinic (The) | Toronto Downtown North |
| Toronto Pflag, Toronto | Toronto |
| Total Care Transport Services | Milton |
| Tottering Biped Theatre | Burlington |
| Tourette Canada, Hamilton, Halton and Niagara Region Chapter | Burlington |
| Trans Lifeline | USA |
| Trillium Health Partners, Credit Valley Hospital, Genetics Program | Mississauga |
| Trillium Health Partners, Credit Valley Emergency Department, Credit Valley Hospital | Mississauga |
| Trillium Health Partners, Credit Valley Hospital | Mississauga |
| Trillium Photographic Club | Burlington |
| Trout Unlimited Canada, Environmental Improvement Group | Halton Region |
| TrueCare Medical Centre | Milton |
| Turning Point Youth Services, Wellesley Street Office, TPYS Shelter | Toronto |
| TVO ILC | Toronto |
| TVO ILC, TVO Mathify | Toronto |
| Tyandaga Tennis Club | Burlington |
| Tyrsa Ukrainian Dance and Bandura School | Burlington |
