| Only Barber Ltd | Other services | 2020 |
| Onplan(Uk) Ltd | Real estate | 2020 |
| Onspeedwell Services Ltd | Construction | 2025 |
| Opal Build Ltd | Construction | 2021 |
| Opitome Limited | Wholesale & retail | 2013 |
| Optima Distribution Limited | Wholesale & retail | 2023 |
| Optimal Cadence Limited | Professional & scientific | 2025 |
| Optimal Vent Limited | Construction | 2021 |
| Opusflow Limited | Professional & scientific | 2010 |
| Orange Investments (London) Ltd | Real estate | 2023 |
| Orangutangu Limited | Hospitality | 2018 |
| Orchard Cremations Limited | Other services | 2026 |
| Orchard Farm Residents Limited | Administrative & support | 1999 |
| Orcl Land Limited | Financial services | 2022 |
| Order Zero Ltd | Information & communication | 2024 |
| Oreophilus Ltd | Information & communication | 2013 |
| Organic Data Holdings Ltd | Financial services | 2022 |
| Organic Data Solutions Ltd | Information & communication | 2020 |
| Organic Russian Hair Ltd | Wholesale & retail | 2026 |
| Oriel Advisers Limited | Professional & scientific | 2013 |
| Original Sound Promotions Ltd | Arts & recreation | 2025 |
| Orion Financial Management Limited | Financial services | 2020 |
| Orion Light Communications Limited | Information & communication | 2025 |
| Orka Golf Limited | Wholesale & retail | 2007 |
| Orlando Crowcroft Limited | Professional & scientific | 2025 |
| Osborn Recovery Services Limited | Wholesale & retail | 2008 |
| Osborn Transport Services Limited | Wholesale & retail | 2005 |
| Osborne Morris and Morgan Limited | Professional & scientific | 2020 |
| Osborne Morris and Morgan Trust Corporation Limited | Administrative & support | 2018 |
| Oscarsworld Ltd | Wholesale & retail | 2026 |
| OSO Limited | Manufacturing | 2023 |
| OSQ Collection Ltd | Manufacturing | 2024 |
| Ottaway Therapy Ltd | Health & social care | 2026 |
| OUR Garden Rooms Ltd | Other services | 2020 |
| Ourgreenroots Ltd | Water & waste | 2026 |
| Out-There UK Group Limited | Professional & scientific | 2020 |
| Overbridge Management Services Limited | Transport & logistics | 2000 |
| Overmould Ltd | Manufacturing | 2016 |
| Oxford Synthesiser Company Limited | Extraterritorial | 1984 |
| Oxford Word of Faith Limited | Other services | 2018 |
| Oxleigh Construction Ltd | Construction | 2026 |
| Oxleigh Property Ltd | Real estate | 2025 |
| Ozgur Ltd | Real estate | 2025 |
| P & C Precision Engineers Limited | Professional & scientific | 1995 |
| P & C Precision Trustees Limited | Administrative & support | 2023 |
| P & S Abraham Limited | Construction | 2013 |
| P a Communications Limited | Manufacturing | 1984 |
| P Gale Consultancy Ltd | Financial services | 2025 |
| P J C Holdings Ltd | Financial services | 2023 |
| P N Brickwork Limited | Construction | 2006 |
| P T Autos Limited | Wholesale & retail | 2012 |
| P&K Accountancy Limited | Professional & scientific | 2018 |
| P.A.S Connections Ltd | Construction | 2023 |
| P1RAU Ltd | Wholesale & retail | 2018 |
| Pablobm Consulting Limited | Information & communication | 2019 |
| Pace LCV Solutions Ltd | Wholesale & retail | 2025 |
| Pace Services Truck Sales Limited | Wholesale & retail | 2014 |
| Packpost International Ltd. | Transport & logistics | 1996 |
| Packpost Services Limited | Other services | 1974 |
| Padel Warehouse Limited | Arts & recreation | 2025 |
| Page Professional Ltd | Professional & scientific | 2015 |
| Paideia Labs Ltd | Information & communication | 2025 |
| Palladio Exterior Design Solution Limited | Construction | 2003 |
| Pallet Truck Depot Limited | Professional & scientific | 2013 |
| Pallet Truck Warehouse Limited | Wholesale & retail | 2004 |
| Palm Bridge Productions Ltd | Information & communication | 2023 |
| Palm Technology Ltd | Information & communication | 2024 |
| Palmer Property Developments Ltd | Real estate | 2020 |
| Palo Santo Consulting Ltd | Professional & scientific | 2023 |
| Pamadzie Limited | Health & social care | 2015 |
| Pamana Limited | Arts & recreation | 2013 |
| Pamata Ltd | Real estate | 2026 |
| Panacea Property Services Ltd | Extraterritorial | 2008 |
| Panther Protection Group Limited | Administrative & support | 2024 |
| Papa V Limited | Manufacturing | 2024 |
| Papermakers Lodge RTM Company Limited | Households | 2023 |
| PAR Engineering (MK) Limited | Administrative & support | 1999 |
| PAR Rigging Ltd | Information & communication | 2023 |
| Para Media Limited | Information & communication | 2022 |
| Paragon Building RTM Company Limited | Households | 2024 |
| Parallel Proximity Limited | Information & communication | 2022 |
| Paramount Shopfitting Company Limited | Water & waste | 1961 |
| Park Street (Aylesbury) Management Company Limited | Households | 2006 |
| Parkfields Management Company (Feltham) Limited | Households | 1994 |
| Parks and Gardens Limited | Professional & scientific | 2014 |
| Parks for People CIC | Administrative & support | 2018 |
| Parkview Close Management Company Limited | Households | 1993 |
| Parris Solutions Limited | Information & communication | 2014 |
| Partnr Soya Alternative Sourcing Limited | Agriculture & fishing | 2021 |
| Partridge Mortgage Services Limited | Financial services | 2016 |
| PAS Engineering Solutions Limited | Administrative & support | 2010 |
| Patch IT Solutions Ltd | Information & communication | 2021 |
| Pattison Lane Estate Agents Limited | Financial services | 2003 |
| Paul Flum International Displays Limited | Manufacturing | 2014 |
| Paul O'Dell Limited | Transport & logistics | 2017 |
| Paul Phear Ltd | Information & communication | 2021 |
| Paul Whittington Group Limited | Manufacturing | 2018 |
| Paul's Property 101 Ltd | Real estate | 2020 |
| Paws Grooming and Hydrotherapy Ltd | Other services | 2023 |
| Payne and Starnes (U.K.) Limited | Wholesale & retail | 1973 |