| OWR (Oxford) Limited | Wholesale & retail | 2025 |
| Oxartis Limited | Professional & scientific | 2020 |
| Oxbuck Wine Limited | Wholesale & retail | 2020 |
| Oxenbury Partners Ltd | Administrative & support | 2013 |
| Oxentia Foundation Limited | Professional & scientific | 2020 |
| Oxentia Ltd | Professional & scientific | 2016 |
| Oxford Anime CON Ltd | Administrative & support | 2025 |
| Oxford Caravan Centre Limited | Wholesale & retail | 1967 |
| Oxford Card Show Ltd | Administrative & support | 2024 |
| Oxford German Motors Ltd | Wholesale & retail | 2025 |
| Oxford Maritime Consultancy Company Limited | Professional & scientific | 2019 |
| Oxford Mestar Limited | Professional & scientific | 2013 |
| Oxford Molecular Biosensors Limited | Professional & scientific | 2017 |
| Oxford Mortgage Company Limited | Financial services | 2007 |
| Oxford Official Walking Tours Limited | Administrative & support | 2025 |
| Oxford Optronix Holdings Limited | Financial services | 2022 |
| Oxford Optronix Property Limited | Real estate | 2022 |
| Oxford Premier Stays Ltd | Real estate | 2024 |
| Oxford Technology ECF (FP) LLP | | 2007 |
| Oxford Technology ECF (GP) LLP | | 2007 |
| Oxford Technology ECF (GP) Member Limited | Financial services | 2012 |
| Oxford Technology Enterprise Capital Fund LP | | 2007 |
| Oxford Wheel Repairs Limited | Wholesale & retail | 2015 |
| OXFORD8 Limited | Information & communication | 2010 |
| Oxfordshire Homes and Gardens Ltd | Construction | 2019 |
| Oxfordshire Land Lease Limited | Real estate | 2018 |
| Oxon Engineering Ltd | Professional & scientific | 2024 |
| OXYGEN8 Solutions Limited | Professional & scientific | 2003 |
| P Nair Limited | Professional & scientific | 2013 |
| P S Curtis (2014) Limited | Professional & scientific | 2014 |
| P.S. Alliance Ltd | Information & communication | 2014 |
| Pacific Marketing Ltd | Information & communication | 1995 |
| Pacific Produce Limited | Wholesale & retail | 2010 |
| Page Media Limited | Manufacturing | 2019 |
| Pallant&Co Ltd | Real estate | 2025 |
| Palmer and Partners Architects Ltd | Professional & scientific | 2015 |
| Pamfield & Co Limited | Real estate | 2014 |
| Panther Aquacut Limited | Manufacturing | 2003 |
| Park Walk Media Limited | Information & communication | 2020 |
| Parker Anaesthetics Ltd | Health & social care | 2026 |
| Partridge Projects Limited | Extraterritorial | 2015 |
| Passengers Travel Ltd | Administrative & support | 2024 |
| Patrick Quinn Limited | Construction | 2007 |
| Patrons Pizza Limited | Hospitality | 2018 |
| Paul Currah Studio Ltd | Professional & scientific | 2017 |
| Peachey Garages Limited | Wholesale & retail | 1978 |
| Peak Performance Presence Limited | Professional & scientific | 2005 |
| Pearson Five Limited | Information & communication | 2013 |
| Pebblerose Limited | Real estate | 2004 |
| Pemberton AI Ltd | Information & communication | 2019 |
| Pemberton Group Holdings Ltd | Information & communication | 2024 |
| Pemberton IP Ltd | Information & communication | 2024 |
| Pemberton Sales Ltd | Information & communication | 2024 |
| Pentangle Technology Limited | Information & communication | 2017 |
| Percept Spatial Limited | Professional & scientific | 2024 |
| Performance Nutrition Insider Ltd | Professional & scientific | 2024 |
| Personal Plane Services Limited | Other services | 1960 |
| Pervasive Home Technologies Ltd | Information & communication | 2008 |
| Petcare Thame Ltd | Wholesale & retail | 2012 |
| Pete Quartly Physiotherapy Limited | Health & social care | 2006 |
| Pharma Market Access Solutions Limited | Professional & scientific | 2009 |
| Pharmafor Ltd | Professional & scientific | 2008 |
| Pharmaspace (Aylesbury) Limited | Health & social care | 2014 |
| Phil D'Souza Ltd | Professional & scientific | 2025 |
| Phoenix Electrical Thame Ltd | Wholesale & retail | 2013 |
| Phoenix Inn Limited | Hospitality | 2024 |
| Phoenix Scanner Graphics Limited | Real estate | 1981 |
| Photo-Sonics International Limited | Professional & scientific | 1991 |
| Pigeon Vision Ltd | Information & communication | 2023 |
| Pikehaven Limited | Construction | 1989 |
| Pivotal Communications Limited | Information & communication | 2009 |
| Pizza Primavera Ltd | Hospitality | 2024 |
| PJ and CLO Ltd | Professional & scientific | 2023 |
| Placefinder Consultancy Ltd | Professional & scientific | 2024 |
| Plastic Seeds Ltd | Information & communication | 2022 |
| Plated Foods Ltd | Information & communication | 2026 |
| Platinum Landscaping Limited | Administrative & support | 2007 |
| Plato Energy Limited | Professional & scientific | 2025 |
| Pleka Limited | Professional & scientific | 2014 |
| Plexalis Ltd | Information & communication | 2018 |
| Plumb-Warehouse Limited | Wholesale & retail | 2004 |
| Plumbergy Ltd | Construction | 2023 |
| Plume of Light Ltd | Professional & scientific | 2019 |
| PMT Holdings Limited | Administrative & support | 2006 |
| Pocket Data Limited | Information & communication | 2020 |
| Pohlcon UK Ltd | Wholesale & retail | 1993 |
| Polaron Ltd | Information & communication | 2023 |
| POP Management Ltd | Energy | 2019 |
| Porter Consulting and Management Services Limited | Professional & scientific | 2001 |
| Potted Thame Ltd | Hospitality | 2026 |
| Power Inspired Limited | Manufacturing | 2008 |
| Powerbiking Limited | Wholesale & retail | 1997 |
| Powerweave Studio UK Ltd | Administrative & support | 2026 |
| Precision International (Holdings) Limited | Professional & scientific | 2012 |
| Precision Moulds and Tools Holdings Limited | Professional & scientific | 2020 |
| Precision Moulds and Tools Services Limited | Manufacturing | 2002 |
| Precision Mowing and Lawn Services Limited | Professional & scientific | 2022 |
| Presentable Software Limited | Professional & scientific | 2016 |
| Prestige Engineering Banbury Ltd. | Manufacturing | 2005 |
| Price & Co Southern Limited | Construction | 2021 |