| Phillips Precision Photography Limited | Professional & scientific | 1986 |
| Phillips Property Lettings Limited | Real estate | 2021 |
| Philosophy for Everyone Ltd | Education | 2025 |
| Phoenix and Beau Ltd | Manufacturing | 2016 |
| Phoenix Film and Publishing Limited | Extraterritorial | 2013 |
| Phoenix Instrumentation Limited | Manufacturing | 1993 |
| Phoenix PUB Group Ltd | Hospitality | 2012 |
| Phoenix Sovereign Group Ltd | Real estate | 2024 |
| Phone Parts Europe Limited | Wholesale & retail | 2013 |
| Photodata (Hitchin) Limited | Professional & scientific | 1984 |
| Photodata (Imaging) Limited | Administrative & support | 2000 |
| Photodata Test Services Limited | Administrative & support | 1995 |
| Physio Three Sixty Ltd | Health & social care | 2016 |
| PI Education LLP | | 2021 |
| Pica Pica Ltd | Wholesale & retail | 2025 |
| Pierso, Mummery and Venator Limited | Professional & scientific | 2004 |
| Pilkerton Limited | Extraterritorial | 2025 |
| Pimalai Limited | Health & social care | 2023 |
| Pioneer Roofing Limited | Construction | 2012 |
| Pirate's Grog RUM Ltd | Wholesale & retail | 2012 |
| Pirton Limited | Construction | 2000 |
| Pirton Pre-School | Education | 2010 |
| Pirton Sports and Social Club Limited | Arts & recreation | 2025 |
| PIT Stop Auto Centres (Letchworth) Limited | Wholesale & retail | 1999 |
| Pizzanolimit Ltd | Extraterritorial | 2025 |
| PJ Heating 2019 Limited | Construction | 2019 |
| PJ Mortgages (UK) Limited | Financial services | 2010 |
| PJB Rural Developments Limited | Real estate | 2015 |
| PJM & SON GAS Services Ltd | Construction | 2017 |
| PJN Logistics Ltd | Information & communication | 2021 |
| Pjohnson Holdings Limited | Financial services | 2017 |
| PKN Asset Management Ltd | Professional & scientific | 2024 |
| PKS Power Systems Limited | Construction | 2002 |
| Place Make Ltd | Professional & scientific | 2013 |
| Placewell Advisory Ltd | Professional & scientific | 2025 |
| Plain Limited | Professional & scientific | 2012 |
| Plainn Limited | Wholesale & retail | 2024 |
| Planet Clothing 93 Ltd | Wholesale & retail | 2004 |
| Planet Furniture Limited | Manufacturing | 2014 |
| Planetary Property Ltd | Real estate | 2024 |
| Plant 4 Hire Limited | Administrative & support | 2008 |
| Plasmoulds Limited | Manufacturing | 1946 |
| Plastic Facilities Limited | Manufacturing | 1974 |
| Plasticolor Europe Limited | Wholesale & retail | 2020 |
| Platinum Regulatory Limited | Professional & scientific | 2010 |
| Play Aloud Ltd | Health & social care | 2015 |
| Play Cotton Limited | Wholesale & retail | 2021 |
| Play, Learn and Grow Together Ltd | Health & social care | 2024 |
| Playr Limited | Information & communication | 2009 |
| Pluck Technology Ltd | Professional & scientific | 2025 |
| Plum Medical Services Limited | Health & social care | 2015 |
| Plumb N Go Ltd | Construction | 2010 |
| Plusminus Consulting Limited | Professional & scientific | 2013 |
| PMR Build Limited | Construction | 2017 |
| Pmracing Syndications Limited | Arts & recreation | 2006 |
| Pocket Rockets Hertfordshire Ltd | Administrative & support | 2026 |
| Podium Race & Rally Ltd | Information & communication | 2026 |
| Polar Computer Communications Limited | Information & communication | 1997 |
| Politica Ltd | Professional & scientific | 2020 |
| Polyphonia Ltd | Arts & recreation | 2019 |
| Poplar Court Management Limited | Households | 1983 |
| Poplars Carpentry Contracting Limited | Construction | 2022 |
| Poplars Commercial Contracting Limited | Professional & scientific | 2018 |
| Poplars Construction Ltd. | Construction | 2015 |
| Poplars Developments (UK) Limited | Real estate | 2018 |
| Poplars Group (UK) Limited | Financial services | 2018 |
| Porters END Capital Limited | Extraterritorial | 2019 |
| Porters END Investments | Financial services | 2020 |
| Porthsele Limited | Administrative & support | 2019 |
| Portman Pocket Doors Limited | Manufacturing | 2026 |
| Portmill Hitchin Limited | Real estate | 2025 |
| Positive Response Media Limited | Professional & scientific | 2022 |
| Potens Property Limited | Real estate | 2021 |
| Power and Data UK Ltd | Wholesale & retail | 2024 |
| Power on Demand Finance 1 Limited | Financial services | 2025 |
| Power on Demand Projects (Oxford) Limited | Energy | 2025 |
| Power on Demand Projects Ltd | Construction | 2024 |
| Powerful BI Limited | Information & communication | 2018 |
| Powerfully Birthing Ltd | Other services | 2016 |
| Precision Habitat Ltd | Real estate | 2025 |
| PREHAB4LIFE Ltd | Health & social care | 2023 |
| Premier Children’S Care Ltd | Health & social care | 2026 |
| Premier Commercial Lending Limited | Other services | 2017 |
| Premier NX Emea Limited | Financial services | 2026 |
| Premier NX Limited | Information & communication | 2026 |
| Premier Projects BM Ltd | Construction | 2023 |
| Premier Property Solutions (UK) Limited | Financial services | 2014 |
| Premium Staff Ltd | Health & social care | 2014 |
| Prepare My Property Limited | Construction | 2020 |
| Presence Unlimited Limited | Education | 2026 |
| Presenceathletics Ltd | Education | 2026 |
| Prestige Motors Repair Centre Ltd | Wholesale & retail | 2025 |
| Previn Vadgama Ltd | Transport & logistics | 2026 |
| Pride and Quality Consulting Limited | Professional & scientific | 2018 |
| Prime Estates Limited | Financial services | 1984 |
| Prime Estates Services Limited | Real estate | 1951 |
| Prime GAS Solutions Ltd | Construction | 2020 |
| Prime Mortgage Finance Limited | Financial services | 2016 |
| Prime Peak Services Ltd | Administrative & support | 2026 |
| Prime Property Consultants Limited | Administrative & support | 2023 |