| Oliday Ltd | Professional & scientific | 2024 |
| Olive Construction Services Ltd | Construction | 2021 |
| Oliver Gregory Limited | Administrative & support | 2003 |
| ON Construction Holdings Limited | Financial services | 2025 |
| ON Construction Limited | Construction | 2017 |
| ON Drive Ventures Limited | Professional & scientific | 2014 |
| ON Event Production Co Limited | Other services | 2004 |
| On-The-Move Mobility Ltd | Wholesale & retail | 2006 |
| Oncore Dance Academy Ltd | Education | 2021 |
| Oncore Dance Studios Ltd | Arts & recreation | 2013 |
| Only Sites Limited | Administrative & support | 2026 |
| Oppimine Ltd | Administrative & support | 2021 |
| Optimum IT Services Limited | Information & communication | 2016 |
| Opulentos Domum Ltd | Real estate | 2021 |
| Opus Apparitions Limited | Information & communication | 2017 |
| Opus Consult Ltd | Professional & scientific | 2020 |
| Organic Colour Lounge Ltd | Administrative & support | 2018 |
| ORIANA360 Limited | Information & communication | 2025 |
| Orion Biogenics Ltd | Professional & scientific | 2024 |
| Oryx Northern Properties Ltd | Real estate | 2025 |
| Oryx Residential Properties Ltd | Real estate | 2026 |
| OSH Enterprises Ltd | Wholesale & retail | 2022 |
| Oskie Creative Limited | Information & communication | 2015 |
| Otter Coot LLP | | 2019 |
| OUT + About Showroom Limited | Wholesale & retail | 2010 |
| Outdoor Projects Limited | Hospitality | 2011 |
| Owen Farms (Westbury) Limited | Agriculture & fishing | 1982 |
| OX Heating & Cooling Ltd | Construction | 2025 |
| OX Property Services Ltd | Construction | 2017 |
| OXC Trimmers Limited | Manufacturing | 2021 |
| Oxford Budget and Policy Ltd | Extraterritorial | 2016 |
| Oxford Fire Safety Group Consulting Ltd | Professional & scientific | 2015 |
| Oxford Fire Safety Ltd | Professional & scientific | 2019 |
| Oxford Wills Limited | Professional & scientific | 2006 |
| P & M Ventures Limited | Construction | 2005 |
| P & W Brackley General Movers Ltd | Transport & logistics | 2024 |
| P&R Cassian Investments Ltd | Financial services | 2026 |
| P.R.& I.C.Rymer Limited | Agriculture & fishing | 2004 |
| PA Sales Consultancy Ltd | Wholesale & retail | 2024 |
| Pacific Auto Imports Ltd | Wholesale & retail | 2025 |
| Padel BUG Limited | Arts & recreation | 2026 |
| Padtec Limited | Professional & scientific | 1979 |
| Paint World Elite Limited | Financial services | 2023 |
| Paint World Holdings Limited | Wholesale & retail | 2021 |
| Paintworld Cambridge Limited | Wholesale & retail | 2025 |
| Paintworld Ipswich Limited | Wholesale & retail | 2025 |
| Paintworld Norwich Limited | Wholesale & retail | 2025 |
| Paintworld Reading Limited | Wholesale & retail | 2025 |
| Paintworld Romford Limited | Wholesale & retail | 2025 |
| Pallas Connections Limited | Manufacturing | 1993 |
| Pandora Pubs Limited | Hospitality | 2010 |
| Pannetier Composites Ltd | Professional & scientific | 2026 |
| Paragon Pool Holdings Limited | Financial services | 2023 |
| Park Manor Consulting Limited | Agriculture & fishing | 2015 |
| Parkland Fencing Limited | Construction | 2005 |
| Parko Developments Ltd | Construction | 2021 |
| Parr Avion Engineering Ltd | Manufacturing | 2023 |
| Pasta Delight Ltd | Hospitality | 2023 |
| Patjl Limited | Financial services | 2018 |
| Paul Grimshaw Vehicle Movements Limited | Transport & logistics | 2011 |
| Paul Stirling Limited | Arts & recreation | 2018 |
| Paul Summerfield Limited | Transport & logistics | 2011 |
| Pauline Pugh Finance and Leasing Limited | Financial services | 2013 |
| PAW PAW (Banbury) Limited | Administrative & support | 2004 |
| PAW PAW (Warwick) Limited | Administrative & support | 2005 |
| PAW PAW Limited | Administrative & support | 2002 |
| Pawpaw (Bridge Street) Limited | Administrative & support | 2022 |
| Paxton Renovations Limited | Construction | 2018 |
| Pcvs Travel Ltd | Transport & logistics | 2025 |
| Pcwg Investments Limited | Real estate | 2023 |
| PD Motorsports Limited | Professional & scientific | 2014 |
| Pearmine Health Ltd | Manufacturing | 2016 |
| Pebbles PR Limited | Administrative & support | 2005 |
| Pembroke Partners Limited | Financial services | 2014 |
| Pensions Administration Standards Association CIC | Other services | 2008 |
| People and PAY Ltd | Professional & scientific | 2018 |
| Perfection Paints Ltd | Wholesale & retail | 2014 |
| Perse Perspective Consultancy Limited | Professional & scientific | 2021 |
| Peter Drivers Solution Ltd | Transport & logistics | 2020 |
| Peter North and Partners Limited Liability Partnership | | 2004 |
| Peter North and Partners Services Limited | Professional & scientific | 1994 |
| Petite Argent Ltd | Wholesale & retail | 2009 |
| Pettifer Properties Ltd | Real estate | 2016 |
| PFP Wholesale Ltd | Wholesale & retail | 2025 |
| PFX Motorsports Ltd | Manufacturing | 2021 |
| PGL Investments Ltd | Real estate | 2025 |
| Phases Creative Limited | Information & communication | 2023 |
| Phoenaix Ltd | Professional & scientific | 2025 |
| Phoenix Fire Detection Limited | Construction | 2003 |
| Phronetic.Ly Ltd | Professional & scientific | 2024 |
| Piccalilly Properties Limited | Real estate | 2024 |
| Pillow WAD Limited | Manufacturing | 1999 |
| Pilot Performance Ltd | Arts & recreation | 2020 |
| Pimlico Group Limited | Financial services | 2018 |
| Pimlico Holdco Limited | Professional & scientific | 2010 |
| Pimlico Plumbers Limited | Construction | 1986 |
| Pipador Limited | Professional & scientific | 2023 |
| Pipingpugs Ltd | Wholesale & retail | 2020 |
| Pivotal UK Consulting Limited | Professional & scientific | 2022 |
| Pixel Perfect Ltd | Information & communication | 2014 |