| Oak Branch Medical Clinic, Family Practice and Walk-in Clinic | Oakville |
| Oak Lake Medical Centre | Oakville |
| Oak Park Family Care Centre, Family Practice and Walk-in Clinic | Oakville |
| Oak Park Medical Clinic | Oakville |
| Oak Park Neighbourhood Centre | Oakville |
| Oak Park Neighbourhood Centre, Food Bank | Oakville |
| Oak Park Neighbourhood Centre, Low Income Supports | Oakville |
| Oak Park Neighbourhood Centre, Churchill Neighbourhood Centre | Oakville |
| Oak Park Neighbourhood Centre, Child & Youth Programs | Oakville |
| Oak Park Neighbourhood Centre, Family & Preschool Programs | Oakville |
| Oak-Trafalgar Medical Clinic, Family Practice and Walk-in Clinic | Oakville |
| Oakville & District Kennel Club | Oakville |
| Oakville & Milton Humane Society | Oakville |
| Oakville & Milton Humane Society, Barkin' Bin Thrift Store | Oakville |
| Oakville (Milton) Model Flying Club | Milton |
| Oakville Aquatic Club | Oakville |
| Oakville Art Society | Oakville |
| Oakville Camera Club | Oakville |
| Oakville Chamber Orchestra | Oakville |
| Oakville Chinese Network Society, Cultural Heritage Group | Oakville |
| Oakville Choir for Children & Youth | Oakville |
| Oakville Choral | Oakville |
| Oakville Community Centre for Peace, Ecology and Human Rights | Oakville |
| Oakville Community FIRST Robotics Team, Orbit Robotics | Oakville |
| Oakville Cricket Club | Oakville |
| Oakville Curling Club | Oakville |
| Oakville Cycling Club | Oakville |
| Oakville Galleries, Art Classes and Camps | Oakville |
| Oakville Galleries, Elementary and Secondary School Programs in English and French | Oakville |
| Oakville Girls Softball Association | Oakville |
| Oakville Gymnastics Club | Oakville |
| Oakville Health Centre Clinic, Family Practice, Walk-in Clinic and Urgent Care | Oakville |
| Oakville Hornets Girls Hockey Association | Oakville |
| Oakville Horticultural Society | Oakville |
| Oakville Improv Theatre Company | Oakville |
| Oakville Lawn Bowling Club | Oakville |
| Oakville Lions Club | Oakville |
| Oakville Little League Baseball | Oakville |
| Oakville Masters Swim Club | Oakville |
| Oakville Minor Baseball Association | Oakville |
| Oakville Minor Lacrosse Association | Oakville |
| Oakville Museum At Erchless Estate, Summer Day Camps | Oakville |
| Oakville Parent-Child Centre, Oakville - 461 North Service Rd W - Main Location, Parent, Child & Family Programs | Oakville |
| Oakville Parent-Child Centre, Oakville - 481 North Service Rd W - Satellite Location | Oakville |
| Oakville Parent-Child Centre, Oakville - Oakwood Public School | Oakville |
| Oakville Parent-Child Centre, Oakville - Queen Elizabeth Park Community and Cultural Centre | Oakville |
| Oakville Pickleball Association, Athletic Association | Oakville |
| Oakville Players | Oakville |
| Oakville Public Library, Central Branch, Branch Specific Services | Oakville |
| Oakville Public Library, Accessible Collections & Services | Oakville |
| Oakville Public Library, Central Branch, Community Food Corner | Oakville |
| Oakville Public Library, Clearview Branch, Branch Specific Services | Oakville |
| Oakville Public Library, Clearview Branch, Community Food Corner | Oakville |
| Oakville Public Library, Creation Zone | Oakville |
| Oakville Public Library, Glen Abbey Branch, Branch Specific Services | Oakville |
| Oakville Public Library, Glen Abbey Branch, Community Food Corner | Oakville |
| Oakville Public Library, Iroquois Ridge Branch, Branch Specific Services | Oakville |
| Oakville Public Library, OPL Express | Oakville |
| Oakville Public Library, Newcomer Programs | Oakville |
| Oakville Public Library, Sixteen Mile Branch, Branch Specific Services | Oakville |
| Oakville Public Library, White Oaks Branch, Branch Specific Services | Oakville |
| Oakville Public Library, Woodside Branch, Branch Specific Services | Oakville |
| Oakville Rangers Hockey Club | Oakville |
| Oakville React | Oakville |
| Oakville Renegades Track Club | Oakville |
| Oakville Runners Club | Oakville |
| Oakville Soccer Club | Oakville |
| Oakville Soccer Club, Breaking Barriers Program | Oakville |
| Oakville Speed Skating Club | Oakville |
| Oakville Suzuki Association | Oakville |
| Oakville Symphony | Oakville |
| Oakville Symphony Youth Orchestra | Oakville |
| Oakville Thunder Volleyball Club | Oakville |
| Oakville Town Medical Clinic, Walk-in Clinic and Family Practice | Oakville |
| Oakville Track & Field Club | Halton Region |
| Oakville Trafalgar Badminton Club, Recreational Badminton | Oakville |
| Oakville Vocal Arts Festival | Oakville |
| Oakville Wind Orchestra | Oakville |
| Oakville Yacht Squadron, Sailing School | Oakville |
| Oakville. Parks and Open Space, Lions Valley Park | Oakville |
| Oakville. Parks and Open Space, Outdoor Skating Rinks | Oakville |
| Oakville. Parks and Open Space, Splash Pads | Oakville |
| Oakville. Parks and Open Space, Trail System | Oakville |
| Oakville. Parks and Open Space, Oakville Harbours | Oakville |
| Oakville. Recreation and Culture, Aquatics Programs | Oakville |
| Oakville. Recreation and Culture, Glen Abbey Community Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Indoor and Outdoor Swimming Pools | Oakville |
| Oakville. Recreation and Culture, Iroquois Ridge Community Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Joshua's Creek Arenas, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Kinoak Arena, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Maple Grove Arena, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Oakville Recreational Leagues | Oakville |
| Oakville. Recreation and Culture, Inclusion and Support Services | Oakville |
| Oakville. Recreation and Culture, Recreation Subsidy Programs | Oakville |
| Oakville. Recreation and Culture, Oakville Trafalgar Community Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Preschool Programs | Oakville |
| Oakville. Recreation and Culture, Public Skating | Oakville |
| Oakville. Recreation and Culture, Queen Elizabeth Park Community and Cultural Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, River Oaks Community Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, School Break Camps and Workshops | Oakville |
| Oakville. Recreation and Culture, Sixteen Mile Sports Complex, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Skateboard Parks | Oakville |
| Oakville. Recreation and Culture, Trafalgar Park Community Centre, Recreation Facilities & Programs | Oakville |
| Oakville. Recreation and Culture, Youth Programs | Oakville |
| Oakville. Transit | Oakville |
| Oakville. Transit, care-A-van | Oakville |
| Oakvillegreen Conservation Association | Oakville |
| Oasis Centre des femmes, Community Services, Brampton Satellite Office | Brampton |
| Oasis Youth Care Programs, Oakville, Transitional Support Services for Youth | Oakville |
| OCASI - Ontario Council of Agencies Serving Immigrants, NewYouth.ca | Ontario |
| OCASI - Ontario Council of Agencies Serving Immigrants, Settlement.Org | Ontario |
| OCASI - Ontario Council of Agencies Serving Immigrants, WelcomeOntario.ca | Ontario |
| OCASI - Ontario Council of Agencies Serving Immigrants, OCASI | Toronto |
| Ombudsman Ontario, Children and Youth Unit | Toronto |
| One Health Medical Center, Oakville, Family Practice and Walk-in Clinic | Oakville |
| One Stop Talk | Ontario |
| Ontario Addiction Treatment Centres, Methadone Maintenance Treatment | Oakville |
| Ontario Autism Coalition | Ontario |
| Ontario Camps Association | Toronto |
| Ontario College Application Service | Guelph |
| Ontario College of Teachers, Toronto | Toronto |
| Ontario Federation for Cerebral Palsy | Etobicoke North |
| Ontario Federation of Agriculture, Guardian Network (The) - Suicide Prevention Program | Ontario |
| Ontario Health, Toronto, HealthForceOntario | Toronto Downtown |
| Ontario Health atHome, Etobicoke Office | Etobicoke Central |
| Ontario Health atHome, Burlington Office | Burlington |
| Ontario Health atHome, Milton Office | Milton |
| Ontario Health atHome, Mississauga Office | Mississauga |
| Ontario Health atHome - Niagara, Hamilton Office | Hamilton |
| Ontario Human Rights Commission | Toronto |
| Ontario Network of Sexual Assault / Domestic Violence Treatment Centres | Toronto |
| Ontario Prader-Willi Syndrome Association | York |
| Ontario Registered Music Teachers Association, Hamilton-Halton Branch - No Physical Address | Halton Region |
| Ontario Track 3 Adaptive Sports Association | Milton |
| Ontario. Ministry of Children, Community and Social Services, Burlington - Itabashi Way, Ontario Disability Support Program | Burlington |
| Ontario. Ministry of Children, Community and Social Services, Burlington - Fairview St, Youth Justice Services | Burlington |
| Ontario. Ministry of Children, Community and Social Services, Ontario Autism Program | Toronto |
| Ontario. Ministry of Children, Community and Social Services, Special Services, Enhanced Respite and Assistance for Children with Disabilities (Mississauga), Mississauga | Mississauga |
| Ontario. Ministry of Children, Community and Social Services. Support Services for Male Survivors of Sexual Abuse Program | Toronto |
| Ontario. Ministry of Children, Community and Social Services. Victim Support Line | Toronto |
| Ontario. Ministry of Colleges and Universities, Student Financial Assistance | Thunder Bay |
| Ontario. Ministry of Finance, Oshawa, Guaranteed Annual Income System | Oshawa |
| Ontario. Ministry of Health, Toronto - University Avenue, Public Health Care | Toronto Downtown Central |
| Ontario. Ministry of Health, Trillium Drug Program | Etobicoke |
| Ontario. Ministry of Health, Health Care Connect | Toronto Downtown Central |
| Ontario. Ministry of Health, Health811 | Toronto Downtown Central |
| Ontario. Ministry of Health, Find a naloxone kit | Ontario |
| Ontario. Ministry of Health, Refugee HealthLine | Toronto Downtown Central |
| Ontario. Ministry of Health, Assistive Devices Program | North York Central |
| Ontario. Ministry of Health, Sexual Health Infoline Ontario | Toronto Downtown |
| Ontario. Ministry of Health, Smoking Cessation Program | Toronto Downtown Central |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Halton Region Office, Employment Ontario Office | Oakville |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Employment Ontario Contact Centre | Toronto |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Ontario Bridge Training Program | Toronto |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, e-Channel | Toronto |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Global Experience Ontario | Toronto |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Ontario Job Creation Partnerships | Toronto |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Pre-Apprenticeship Training Program | Toronto |
| Ontario. Ministry of the Attorney General, Milton Courthouse - Rm 235, Victim / Witness Assistance Program | Milton |
| Ontario. Ministry of the Attorney General, Victim / Witness Assistance Program, Toronto, Court of Appeal of Ontario | Toronto |
| Ontario. Ministry of the Attorney General, Victim / Witness Assistance Program, Toronto, Ontario Review Board | Toronto |
| Ontario. Ministry of the Attorney General, Independent Legal Advice for Survivors of Sexual Assault Program | Toronto |
| Ontario. Ministry of the Attorney General, Hamilton Services, John Sopinka Courthouse, Ontario Victim/Witness Assistance Program | Hamilton |
| Ontario. Ministry of the Attorney General. Office of the Children's Lawyer | Toronto |
| Ontario. Ministry of the Environment, Conservation and Parks, Bronte Creek Provincial Park | Oakville |
| Operation Come Home, Reunite Program | Ottawa |
| Optimal Health, Walk-in Medical Clinic | Burlington |
| Optimist Club of Burlington | Burlington |
| Optimist Club of Oakville | Oakville |
| Osteoporosis Canada | North York East |
| Our Kids Network, Halton Youth Initiative | Halton Region |
| Our Place Peel, Emergency Youth Shelter, Brampton Steelwell | Brampton |
| Our Place Peel, Emergency Youth Shelter, Mississauga | Mississauga |
| Outward Bound Canada, Charitable Programs | Toronto |
| Ovarian Cancer Canada | North York Central |
| Overeaters Anonymous, Oakville / Burlington Area Meetings | Burlington |
