| Older Women's Network, Peterborough - Mailing Address | Peterborough |
| OMNI Health Care, Riverview Manor | Peterborough |
| OMNI Health Care, Springdale Country Manor Nursing Home | Peterborough |
| OMNI Health Care, Pleasant Meadow Manor | Peterborough |
| Omni Health Care, Burnbrae Gardens Long Term Care Facility | Campbellford |
| OMNI Health Care, Frost Manor Long Term Care Facility | Lindsay |
| One City Peterborough, Trinity Community Centre, Trinity Community Centre - Overnight Program | Peterborough |
| Ontario Aboriginal Housing Services, Peterborough, Southeastern Ontario Property Management Office | Peterborough |
| Ontario Addiction Treatment Centres, Peterborough Clinic | Peterborough |
| Ontario Addiction Treatment Centres, Peterborough Clinic | Peterborough |
| Ontario Beekeepers Association, Peterborough - Mailing Address, Central Ontario Beekeepers Association | Peterborough |
| Ontario Caregiver Organization, Online Services/Find Support | Toronto Downtown Central |
| Ontario College of Pharmacists | Toronto Downtown North |
| Ontario College of Social Workers and Social Service Workers | Toronto Downtown North |
| Ontario Federation of Anglers and Hunters, Invading Species Awareness Program | Peterborough |
| Ontario Federation of Anglers and Hunters, Mario Cortellucci Hunting & Fishing Heritage Centre | Peterborough |
| Ontario Federation of Anglers and Hunters, Mobile Service, TackleShare Program | Peterborough |
| Ontario Federation of Anglers and Hunters | Peterborough |
| Ontario Federation of Anglers and Hunters, Shimano Fish Pond | Peterborough |
| Ontario Health Regulators, Mailing Address | Beaverton |
| Ontario Provincial Police, Peterborough County Detachment - Community Policing, Peterborough | Peterborough |
| Ontario Provincial Police, Peterborough, Peterborough County Detachment | Peterborough |
| Ontario Public Interest Research Group, Peterborough | Peterborough |
| Ontario Senior Homeowners' Property Tax Grant | Oshawa |
| Ontario Turtle Conservation Centre | Selwyn Township |
| Ontario. Members of Provincial Parliament, Peterborough-Kawartha Riding, Provincial Constituency Office - Dave Smith | Peterborough |
| Ontario. Ministry of Children, Community and Social Services, Peterborough Office, Ontario Disability Support Program | Peterborough |
| Ontario. Ministry of Children, Community and Social Services, Peterborough, Peterborough Office | Peterborough |
| Ontario. Ministry of Children, Community and Social Services. Support Services for Male Survivors of Sexual Abuse Program | Toronto |
| Ontario. Ministry of Economic Development, Job Creation and Trade, Peterborough | Peterborough |
| Ontario. Ministry of Environment, Conservation and Parks, North Kawartha, Ontario Parks - Kawartha Highlands Provincial Park | Bancroft |
| Ontario. Ministry of Environment, Conservation and Parks, Peterborough - Mailing Address, Natural Resources Information and Support Centre | Peterborough |
| Ontario. Ministry of Environment, Conservation and Parks, Woodview, Ontario Parks - Petroglyphs Provincial Park | North Kawartha |
| Ontario. Ministry of Finance, Oshawa, Guaranteed Annual Income System | Oshawa |
| Ontario. Ministry of Health, No Physical Location, Telehealth Ontario | Toronto Downtown Central |
| Ontario. Ministry of Health, Toronto, Assistive Devices Program | Toronto |
| Ontario. Ministry of Health, Ontario Drug Benefit Program | Toronto |
| Ontario. Ministry of Health, Mailing address only, Trillium Drug Program | Etobicoke |
| Ontario. Ministry of Healthy, Ontario. Ministry of Health, Ontario Health Insurance Plan | Toronto Downtown Central |
| Ontario. Ministry of Labour, Peterborough, Peterborough Enforcement Branch | Peterborough |
| Ontario. Ministry of Labour, Immigration, Training and Skills Development, Peterborough Area Office, Apprenticeship Office, Peterborough Area Office | Peterborough |
| Ontario. Ministry of Northern Development, Mines, Natural Resources and Forestry, District Office - Peterborough | Peterborough |
| Ontario. Ministry of Northern Development, Mines, Natural Resources and Forestry, Southern Region - Peterborough | Peterborough |
| Ontario. Ministry of the Attorney General, Crown Attorney, Peterborough - George St N, Peterborough - George St N | Peterborough |
| Ontario. Ministry of the Attorney General, Ontario Court of Justice - Justice of the Peace, Peterborough - Simcoe St, Peterborough - Simcoe St | Peterborough |
| Ontario. Ministry of the Attorney General, Peterborough - George St N, Victim/Witness Assistance Program | Peterborough |
| Ontario. Ministry of the Attorney General, Peterborough - Simcoe St, Ontario Court of Justice and Superior Court of Justice | Peterborough |
| Ontario. Ministry of the Attorney General, Peterborough - Water St, Superior Court of Justice - Family Court, Peterborough - Water St | Peterborough |
| Ontario. Ministry of the Attorney General, Small Claims Court, Peterborough - Simcoe St, Peterborough - Simcoe St | Peterborough |
| Ontario. Ministry of the Attorney General. Office of the Public Guardian and Trustee | Toronto Downtown Central |
| Ontario. Ministry of the Attorney General. Office of the Public Guardian and Trustee | Toronto |
| Ontario. Ministry of the Environment, Conservation and Parks, Peterborough District Office, Ontario. Ministry of the Environment, Conservation and Parks, Peterborough District Office | Peterborough |
| Ontario. Ministry of the Solicitor General, Peterborough, Probation and Parole Services, Peterborough | Peterborough |
| Ontario. Ministry of Tourism, Culture and Sport, Peterborough, Regional Tourism Unit | Peterborough |
| Ontario. Ministry of Transportation, Peterborough Bus Terminal, GO Transit - Peterborough GO Bus Service | Peterborough |
| Osteoporosis Canada [Central East], Peterborough | Peterborough |
| Otonabee Municipal Non profit Housing Corporation, Keene - 30 Short Street, Otonabee Court | Keene |
| Otonabee Municipal Non profit Housing Corporation, Keene - 35 Pinecrest Avenue, Monaghan Court | Keene |
| Otonabee Region Conservation Authority, Lakefield - Birch Island Rd, Selwyn Beach Conservation Area | Selwyn Township |
| Otonabee Region Conservation Authority, Peterborough - Milroy Dr, Otonabee Region Conservation Authority - Administration | Peterborough |
| Otonabee Region Conservation Authority, Warsaw - Caves Rd, Warsaw Caves Conservation Area | Douro-Dummer |
| Otonabee-South Monaghan Food Cupboard | Keene |
| Otonabee-South Monaghan. Municipal Office, Bailieboro Library - The Boutique, Bailieboro - County Rd 28 | Bailieboro |
| Otonabee-South Monaghan. Municipal Office, Bailieboro Library Branch, Bailieboro Library, Bailieboro - County Rd 28 | Bailieboro |
| Otonabee-South Monaghan. Municipal Office, Gayle Nelson Keene Library - Two Small Rooms, Keene - County Rd 2 | Otonabee-South Monaghan |
| Otonabee-South Monaghan. Municipal Office, Keene - Mailing Address, Friends of Otonabee-South Monaghan Public Library | Otonabee-South Monaghan |
| Otonabee-South Monaghan. Municipal Office, Keene, Department of Fire and Emergency Services | Otonabee-South Monaghan |
| Otonabee-South Monaghan. Municipal Office | Keene |
| Otonabee-South Monaghan. Municipal Office, Stewart Hall - Matchett Line, Stewart Hall Library | Peterborough |
| Otonabee-South Monaghan. Municipal Office, Two Small Rooms, Keene Library Branch (Basement), Gayle Nelson Keene Library | Otonabee-South Monaghan |
