Companies catalogue
- OASYS Healthcare, Uxbridge
- OCL Crushing& Trucking, Sudbury
- ONTARIO TAR AND CHIPPING, Sudbury
- OPG Health Physics Whitby, Whitby
- OVERT, Oshawa
- Oak Knoll Stables, Campbellcroft
- Oak St Housing Co-Operative, Toronto
- Oakwood Retirement Communities, Whitby
- Oasis Co-Operative Homes Inc, Sudbury
- Observation Deck, Toronto
- Octapixx Worldwide, Toronto
- Odsp Office, Oshawa
- Odyssey Home & Leisure Products, Oshawa
- Oey Trading Co, Toronto
- Off Centre DJ School, Toronto
- Office Extension, Brantford
- Oil Changers, Oshawa
- Oil Changers, Whitby
- Oil Changers, Markham
- Oil Changers, Toronto
- Oishi Maki, Whitby
- Olde Gaol Museum, Lindsay
- Ole Lang Signs & Neon, Ajax
- Olive That! Tasting Bar, Whitby
- Olympiads School, Toronto
- Omar Aviation Ltd, Sudbury
- Omega Health and Fitness, Toronto
- Omega Magic Photo, Ajax
- On Track Safety Ltd, Markham
- One Tree Studio Inc., Markham
- One York - Public Parking - Lot #501, Toronto
- One-Stop Medical Centre, Toronto
- Oneroot Inc., Markham
- Onlink Monuments Factory Outlet, Toronto
- Ontario Court of Justice, Oshawa
- Ontario Family, Whitby
- Ontario Fantasy Movies, Oshawa
- Ontario Libertarian Party, Toronto
- Ontario Medical Imaging, Toronto
- Ontario Medical Imaging, Richmond Hill
- Ontario Minor Hockey Association, Richmond Hill
- Ontario Municipal Insurance Exchange, Markham
- Ontario Philharmonic, Oshawa
- Ontario Power Generation, Pickering
- Ontario Probation & Parole, Whitby
- Ontario Provincial Police, Aurora
- Ontario Provincial Police (OPP), Kawartha Lakes
- Ontario Provincial Police (Opp), Lindsay
- Ontario Provincial Police - Whitby Detachment, Whitby
- Ontario Railings and Ironworks, Oshawa
- Ontario Retail Sales Tax, Whitby
- Ontario Retirement Living Homes, Senior Housing and Homecare, Retirement Place, Courtice
- Ontario Science Centre, Toronto
- Ontario Society of Occupational Therapists, Toronto
- Ontario Street Theatre, Port Hope
- Ontario Volunteer Emergency Response Team Inc, Oshawa
- Ontario Youth Soccer League, Markham
- Opseu Local 340, Oshawa
- Optimum Bodies Personal & Team Training, Bowmanville
- Optometrists, Whitby
- Orange Julius, Ajax
- Orangetheory Fitness, Vaughan
- Orchard Park, Toronto
- Orchard Villa Retirement Residence, Pickering
- Orchestra Toronto, Toronto
- Orchid Greens, Toronto
- Organization of Canadian Nuclear Industries, Pickering
- Original Congee, Toronto
- Ortho Dynamics Pedorthic Centre, Newmarket
- Ortho Solutions Ltd, Whitby
- Ortho-Tec Limited, Oshawa
- OrthoProActive Consultants Inc., Markham
- Orthotic Concept Inc, Markham
- Orthotics Prosthetics Canada, Toronto
- Osaka Sushi, Markham
- Oshawa, Oshawa
- Oshawa Centre Orthodontics, Oshawa
- Oshawa Clinic Physiotherapy, Oshawa
- Oshawa Community Care, Whitby
- Oshawa Monument Company, Courtice
- Oshawa Physiotherapy & Rehabilitation Centre, Oshawa
- Oshawa Pier, Lake
- Oshawa South Chiropractic Clinic, Oshawa
- Oshawa Speech And Language Centre, Oshawa
- Oshawa Valley Park Co-Operative Homes Inc, Oshawa
- Oshawa Wellness Centre Inc, Oshawa
- Oshio Restaurant, Markham
- Osisko Plaster, Markham
- Osmow's, Toronto
- Osmow's - Richmond Hill, Richmond Hill
- Osmows, Ajax
- Otter Creek Centre, Toronto
- Our Country Favourites, Sudbury
- Outdoor Exposure, Sudbury
- Ove Industrial Design Ltd, Toronto
- Owl Academy Tutoring, Pickering
- Oxford Learning Scarborough Bluffs, Toronto
- Oxford Medical Imaging, Toronto
- Oxford Medical Imaging, Vaughan
- o2b, Richmond Hill