| Oliphant Builders Limited | Construction | 2018 |
| Olivegreen Systems Limited | Information & communication | 2016 |
| OMC Consumables Limited | Wholesale & retail | 2017 |
| OMG Entertainments Limited | Arts & recreation | 2014 |
| ON Sea Group Limited | Information & communication | 2026 |
| Once Upon a Globe Limited | Hospitality | 2025 |
| One Simple Switch Limited | Other services | 2018 |
| One Stop Driveways Specialists Limited | Other services | 2022 |
| One Stop Roofing Specialists Limited | Construction | 2022 |
| ONEPOINT618 Limited | Wholesale & retail | 2006 |
| Ontatile Ltd | Real estate | 2021 |
| Onyx Power Construction Limited | Construction | 2026 |
| Onyx Power Group Limited | Financial services | 2022 |
| Onyx Power Services Limited | Construction | 2021 |
| Onyx Power Testing Limited | Construction | 2022 |
| Ooseven Healthcare Consulting Ltd | Public administration | 2026 |
| Optimum Facilities Management Ltd | Administrative & support | 2009 |
| Opulent Co Living Limited | Real estate | 2024 |
| Orenda Connect UK Limited | Financial services | 2024 |
| Organisation for Conflict Management and Reconstruction Ltd | Information & communication | 2021 |
| Orvella Events Ltd | Professional & scientific | 2026 |
| OSR Lettings Ltd | Real estate | 2020 |
| Otterdesign Limited | Information & communication | 1999 |
| Over Site Security and Tracking Ltd | Administrative & support | 2024 |
| Oxford Human Sciences Limited | Administrative & support | 1988 |
| Oxford Norm Dimensions Limited | Administrative & support | 2018 |
| P & a Hydraulics Limited | Manufacturing | 1979 |
| P J Downs & Sons Limited | Transport & logistics | 2019 |
| P J Marsh Roofing Ltd | Construction | 2022 |
| P J Rushman Limited | Real estate | 2003 |
| P M J a Limited | Professional & scientific | 2017 |
| P M J Accountants Ltd | Professional & scientific | 2001 |
| P R B Contracts Limited | Construction | 2015 |
| P S Shelley Master Thatcher Limited | Construction | 2015 |
| P Wilson Maintenance Limited | Construction | 2014 |
| P&B Property Development Ltd | Construction | 2017 |
| P&P Imports Ltd | Wholesale & retail | 2021 |
| P. Stone Ltd | Financial services | 2003 |
| P.F.C. Flooring Supplies Limited | Construction | 1984 |
| P.Saunders Holdings Limited | Real estate | 2023 |
| Pace Cars Ltd | Wholesale & retail | 2017 |
| Padel HQ Limited | Arts & recreation | 2024 |
| Palace IT Limited | Information & communication | 2002 |
| Palfrey Nominees Limited | Administrative & support | 1978 |
| Palladio Maintenance, Supplies and Procurement Limited | Other services | 2023 |
| Palmlake Properties Limited | Construction | 1982 |
| Panda Portfolios Limited | Administrative & support | 2023 |
| Parafficient Limited | Financial services | 2020 |
| Paragon Commodities Limited | Administrative & support | 2002 |
| Paramed Healthcare Ltd | Health & social care | 2024 |
| Paramount Medical Training Ltd | Education | 2021 |
| Parc Cynog Wind Farm Limited | Energy | 1993 |
| Parino Limited | Other services | 2015 |
| Parkland Consultants Limited | Professional & scientific | 2023 |
| Parthnikita Ltd | Wholesale & retail | 2026 |
| Partner Consulting Limited | Manufacturing | 2020 |
| Parvez Limited | Financial services | 2018 |
| Pass Bike Ltd | Wholesale & retail | 2015 |
| Pathos Therapy Ltd | Health & social care | 2025 |
| Pattmans Limited | Information & communication | 2007 |
| Paul Davis Financial Planning Limited | Financial services | 2018 |
| Paul Hunt Consultancy Limited | Professional & scientific | 2014 |
| Paulkporter Limited | Professional & scientific | 2022 |
| Pawle & Co Limited | Professional & scientific | 1992 |
| Payments Consulting Services Ltd | Information & communication | 2023 |
| Peaceline Limited | Real estate | 1996 |
| Peacenpoutluxe Ltd | Wholesale & retail | 2023 |
| Peach Motors Ltd | Wholesale & retail | 2010 |
| Pegswood Dataworks Limited | Information & communication | 2024 |
| Pembrook Resourcing Ltd | Administrative & support | 2017 |
| Penbuild Limited | Administrative & support | 2009 |
| Pendine Wind Farm Limited | Energy | 1996 |
| Pepha Trustees Limited | Extraterritorial | 2013 |
| Perfectly Pampered Limited | Other services | 2026 |
| Performance Investments Ltd | Real estate | 2001 |
| Performance Tyre Services Ltd | Wholesale & retail | 2014 |
| Pete's Pictures Ltd | Information & communication | 2022 |
| Petfold Limited | Financial services | 2017 |
| PFS (IFA) Limited | Financial services | 2004 |
| PFS Electrical Services Limited | Construction | 2016 |
| PFV Services Ltd | Construction | 2025 |
| PGB Data Solutions Limited | Information & communication | 2016 |
| Phalanx Labs Ltd | Wholesale & retail | 2021 |
| PHI Ventures Ltd | Extraterritorial | 2008 |
| Philly's Pizza Limited | Hospitality | 2026 |
| Phoebe Properties Ltd | Real estate | 2022 |
| Phoebe's Pantry Limited | Hospitality | 2021 |
| Physical Security Solutions Ltd | Administrative & support | 2019 |
| Physically Fit Sports Therapy Limited | Arts & recreation | 2022 |
| Physio Active Healthcare Ltd | Health & social care | 2016 |
| Pickett Property Rentals Ltd | Real estate | 2025 |
| Pickles & Lillies Childrenswear Limited | Wholesale & retail | 2018 |
| PIE Web Limited | Information & communication | 2012 |
| Pinkglow Ltd | Other services | 2025 |
| Pinomar U.K. Limited | Professional & scientific | 1989 |
| Pinpoint Economics Limited | Professional & scientific | 2018 |
| Pippa Nordberg Consulting Limited | Professional & scientific | 2017 |
| Piramid Safety Ltd | Health & social care | 2017 |
| PJM Drainage Services Ltd | Water & waste | 2022 |
| PJR Secretarial Services Ltd | Administrative & support | 2009 |