| Ovenglo Ltd | Administrative & support | 2005 |
| Over the Wall Property Group Ltd | Real estate | 2024 |
| Oving Road Management Company Limited | Households | 2014 |
| Owen House Residents Association Limited | Professional & scientific | 1981 |
| Owhite Consulting Ltd | Professional & scientific | 2025 |
| OWL Lighting Ltd | Professional & scientific | 1990 |
| Owslebury Game Farm Ltd | Agriculture & fishing | 2024 |
| Oxbridge Associates Limited | Wholesale & retail | 2004 |
| Oxbridge Associates Newco Limited | Wholesale & retail | 2025 |
| Oxbridge Property Associates Limited | Real estate | 2018 |
| Oxford Indices Ltd. | Information & communication | 2004 |
| Oxford Trellis Company Limited | Manufacturing | 2023 |
| Oxygen Properties Ltd | Real estate | 2020 |
| Oyler Properties Ltd | Real estate | 2015 |
| Oyster Self Storage Ltd | Transport & logistics | 2020 |
| P & D & S Ltd | Administrative & support | 2023 |
| P & R Autocentres Limited | Extraterritorial | 1998 |
| P C Channer Farms Limited | Agriculture & fishing | 2011 |
| P C Turner Limited | Wholesale & retail | 2011 |
| P G Carmichael Limited | Manufacturing | 2014 |
| P H Moody Limited | Construction | 2017 |
| P R Willsher Decorating Ltd | Construction | 2011 |
| P R Willsher Developments Ltd | Construction | 2016 |
| P V Projects Ltd | Professional & scientific | 1996 |
| P V Projects Trustees Limited | Professional & scientific | 2015 |
| P.D. Scammell (Management) Limited | Households | 2012 |
| P.D. Smales Limited | Agriculture & fishing | 1975 |
| P1 Advisory Ltd | Professional & scientific | 2026 |
| P2 (UK) Limited | Construction | 2006 |
| P3M Global Limited | Information & communication | 2016 |
| P3MPRO Consulting Ltd | Manufacturing | 2023 |
| Pace PR Limited | Professional & scientific | 2020 |
| Packaging Intelligence Network Limited | Professional & scientific | 1995 |
| Pad&Gom Homes Limited | Real estate | 2025 |
| Paddocks Medical Ltd | Health & social care | 2019 |
| Paddywack Productions Limited | Information & communication | 2005 |
| Paintbox Property Ltd | Real estate | 2020 |
| Palisade Protective Security Advisory Ltd | Professional & scientific | 2026 |
| Pall Mall Principals LLP | | 2007 |
| Palladwr Associates Ltd | Professional & scientific | 2010 |
| Palm Panasia Deane Gate Limited | Hospitality | 2020 |
| Palm Panasia Ltd | Hospitality | 2013 |
| Palmer Wilson Associates Limited | Professional & scientific | 2014 |
| Pami Ltd | Information & communication | 2026 |
| Pangea Broker Services Ltd | Financial services | 2022 |
| Pangea Insurance Brokers Ltd | Financial services | 2018 |
| Pangea Life Limited | Financial services | 2015 |
| Panoramics Stone Ltd | Construction | 2025 |
| Pants and Ting Productions Limited | Information & communication | 2014 |
| Paradigm Media Limited | Administrative & support | 2017 |
| Paragn Network Limited | Professional & scientific | 2021 |
| Paragn Store Ltd | Wholesale & retail | 2019 |
| Parchment Jewellers Limited | Manufacturing | 2008 |
| Parchment Partners Limited | Real estate | 1966 |
| Parchment Place Residents' Association Limited | Households | 2017 |
| Pardyco Limited | Financial services | 2016 |
| Park Corner Creative Limited | Administrative & support | 2002 |
| Park Surveyors GB Limited | Real estate | 2006 |
| Parkford Developments Limited | Construction | 2001 |
| Parkhound Consultancy Ltd | Professional & scientific | 2014 |
| Parkin Surgical and Medical Solutions Limited | Wholesale & retail | 2022 |
| Parkside (Westloats) Management Limited | Real estate | 2003 |
| Parkwood (Winchester) Limited | Households | 2014 |
| Parkwood Property Limited | Other services | 2017 |
| Parmenter House Freehold Limited | Households | 2018 |
| Partnered Growth Ltd | Professional & scientific | 2025 |
| Parton Partners Ltd | Administrative & support | 2023 |
| Partridge Vehicle Rental Limited | Administrative & support | 2023 |
| Party KIT Network CIC | Wholesale & retail | 2020 |
| Partyplus Ltd | Wholesale & retail | 2001 |
| Pasalo CIC | Health & social care | 2017 |
| Passdown Property Company 2 Limited | Financial services | 2019 |
| Passdown Property Company Limited | Real estate | 2007 |
| Patario Limited | Information & communication | 2026 |
| Patel Newsmarket Limited | Wholesale & retail | 2005 |
| Pathwsports CIC | Education | 2022 |
| Patientia Properties Limited | Real estate | 2019 |
| Patrimony Capital Group Limited | Real estate | 2023 |
| Patriot VC Limited | Professional & scientific | 2024 |
| Paul O'Nions Fine Art Limited | Wholesale & retail | 2024 |
| Paul O'Nions Woodworks Ltd | Manufacturing | 2024 |
| Paul Young Consulting (FM) Limited | Professional & scientific | 2025 |
| Paula Biles Psychotherapy Limited | Health & social care | 2014 |
| Paula Jordan Consulting Limited | Professional & scientific | 2003 |
| Paultons Financial Planning Ltd | Professional & scientific | 2020 |
| Paxos Investments Limited | Other services | 2024 |
| Pbah Otterbourne Limited | Real estate | 2025 |
| PBK Properties Ltd | Real estate | 2017 |
| PCC Premier Car Care Ltd | Wholesale & retail | 2016 |
| PCL Ltd | Other services | 2017 |
| PD Barbering Ltd | Other services | 2025 |
| PE Procurement Partners Ltd | Professional & scientific | 2022 |
| PE487 Limited | Professional & scientific | 2009 |
| PE489 Limited | Financial services | 2019 |
| Peahen Ventures Limited | Wholesale & retail | 2026 |
| Peak Power Limited | Energy | 2016 |
| Pecunia (Winchester) Limited | Real estate | 2019 |
| Pedigree Properties Limited | Construction | 2004 |
| Pedion 7 Ltd | Construction | 2024 |
| Pedion Real Estate Limited | Construction | 2024 |