| Nesc Productions Limited | Arts & recreation | 2016 |
| Network Consultants | | 1992 |
| New Chamber Opera | Arts & recreation | 1997 |
| New Dawn Pool (Services) Limited | Construction | 2019 |
| Newnham Investments Ltd | Real estate | 2023 |
| Newrace Limited | Administrative & support | 1984 |
| NGA Property Services Ltd | Construction | 2007 |
| Nicola Investments Limited | Real estate | 2000 |
| Nicolian Holidays Limited | Administrative & support | 1996 |
| NIK H Coaching Limited | Education | 2024 |
| Nolasco Ltd | Health & social care | 2013 |
| Norluck Court Management Limited | Real estate | 1990 |
| Norman Rudd (Damp Coursing Division) Limited | | 1970 |
| North Oxford Eyecare Limited | Wholesale & retail | 2006 |
| Northbourne Cottages Limited | Real estate | 2023 |
| NSF Health Sciences Ltd. | Professional & scientific | 1997 |
| Nuffield Orthopaedics Limited | Construction | 1999 |
| O'Gormans Limited | Wholesale & retail | 2000 |
| Oakland Green Limited | Real estate | 2005 |
| Obsolescent Technology Limited | Manufacturing | 2007 |
| Odds Farm Park Ltd. | Agriculture & fishing | 2000 |
| Offox Press Ltd | Information & communication | 2001 |
| Olaris Consulting Limited | Professional & scientific | 2023 |
| Old Mill Motors (Witney) Limited | Wholesale & retail | 1978 |
| Old Parr Limited | Real estate | 1982 |
| Old Regency Securities Limited | Construction | 1988 |
| One Healthtech Ltd | Education | 2018 |
| One Motion EOT Limited | Financial services | 2025 |
| One Oak Construction Ltd | Construction | 2023 |
| Oolite 2016 Ltd | Professional & scientific | 2016 |
| Optech Microscope Services Limited | Administrative & support | 2006 |
| Optics Accounting Ltd | Professional & scientific | 2021 |
| Orchard Close Amenity Limited | Households | 1997 |
| Organics for Kids Limited | Wholesale & retail | 2004 |
| Orlando Television Productions Limited | Information & communication | 1990 |
| Outright Engineering CNC Machining Limited | Manufacturing | 2005 |
| Outright Engineering Fabrication Limited | Manufacturing | 2005 |
| Outright Engineering Holdings Limited | Professional & scientific | 1999 |
| OX Developments Ltd | Construction | 2007 |
| OX1 (Oxford) Limited | Hospitality | 2012 |
| OX1 Residential 1 Ltd | Real estate | 2016 |
| OX1 Residential Ltd | Real estate | 2016 |
| Oxford Biopharma Limited | Professional & scientific | 2005 |
| Oxford Blue Taxis Ltd | Transport & logistics | 2018 |
| Oxford Construction Holdings Limited | Construction | 2021 |
| Oxford Construction Limited | Construction | 2011 |
| Oxford Electrical Products Limited | Manufacturing | 2014 |
| Oxford Fabrication Limited | Manufacturing | 2004 |
| Oxford Furniture Makers Ltd | Construction | 2003 |
| Oxford International Consultancy Ltd | Professional & scientific | 2002 |
| Oxford Iproject Ltd | Transport & logistics | 1997 |
| Oxford Leisure Limited | Hospitality | 2001 |
| Oxford Leuven Surgery Limited | Health & social care | 2002 |
| Oxford Lieder | Arts & recreation | 2005 |
| Oxford Logic Limited | Information & communication | 2002 |
| Oxford Motors Ltd | Wholesale & retail | 2026 |
| Oxford Oak Flooring Limited | Construction | 2025 |
| Oxford Optics Limited | Manufacturing | 2005 |
| Oxford Powershop Limited | Other services | 1995 |
| Oxford Professional Coaching Ltd. | Extraterritorial | 2006 |
| Oxford Professional Consulting Ltd | Education | 2002 |
| Oxford Professional English Ltd | Extraterritorial | 2006 |
| Oxford Retail Data Limited | Administrative & support | 1992 |
| Oxford Shirt Company Limited | Wholesale & retail | 1991 |
| Oxford Software Solutions Ltd | Information & communication | 2007 |
| Oxford Startup Strategies Ltd | Professional & scientific | 2020 |
| Oxford United Stadco Limited | Financial services | 2026 |
| Oxford Vehicle Electronics Limited | Wholesale & retail | 2003 |
| Oxford Violins Limited | Manufacturing | 2003 |
| Oxford Welding Supplies Limited | Wholesale & retail | 1992 |
| Oxfordshire Artificial Lawn Company Limited | Extraterritorial | 2019 |
| Oxfordshire Gardens Trust | Other services | 2002 |
| Oxlot Limited | Professional & scientific | 2001 |
| P & S Robinson Limited | Construction | 1990 |
| P J S Computing Services Limited | Information & communication | 1998 |
| P. D. Hook (Bowland) Limited | Agriculture & fishing | 2002 |
| P. D. Hook (Group) Limited | Professional & scientific | 2004 |
| P.A.Turney Limited | Wholesale & retail | 1958 |
| P.N.Generations LLP | | 2013 |
| PA LM DA Christensen Trading AS Christensen Partners Kingston Hill Farm | | 1998 |
| Paragon (Electrical Contractors) Limited | Energy | 2001 |
| Park Court (Banbury) Limited | Real estate | 1985 |
| Partridge Court (Oxfordshire) Management Company Limited | Real estate | 2000 |
| Pascoe & Waite Limited | Construction | 2005 |
| Pattinson's Book House Limited | Wholesale & retail | 1977 |
| Paul Liss & Sacha Llewellyn | | 2000 |
| Paul Meadows Ltd | Construction | 2003 |
| Paygate Solutions Limited | Financial services | 1996 |
| Pcspools Limited | Manufacturing | 2017 |
| PDG Financial Services Limited | Financial services | 2005 |
| Peaceful Properties Limited | Real estate | 2021 |
| Peak 15 Coaching Limited | Professional & scientific | 2006 |
| Pedder and Summers (Holdings) Limited | Professional & scientific | 1983 |
| Pembroke College Oxford JCR Art Collection Fund Limited | Administrative & support | 1997 |
| Penar Limited | Arts & recreation | 2000 |
| Penn Dragon Properties Limited | Real estate | 1963 |
| Penney's Limited | Administrative & support | 2006 |
| Pentagon Business Services Limited | Administrative & support | 2000 |
| Peter Hamilton Ltd | Information & communication | 2022 |
| Pete’S Holdings Ltd | Real estate | 2023 |