| PBW Consulting Group Limited | Professional & scientific | 2024 |
| PC Blessed Limited | Health & social care | 2015 |
| Pc-Squared Limited | Professional & scientific | 2007 |
| PCA (ST Albans) Limited | Real estate | 2016 |
| PCI Property Holdings Ltd | Real estate | 2016 |
| PCJ Renovations Limited | Construction | 2021 |
| PCP Bespoke Bathrooms Ltd | Construction | 2023 |
| Pdlifts Ltd | Manufacturing | 2020 |
| PDO Services Ltd | Education | 2017 |
| PDP Engineering Ltd | Information & communication | 2017 |
| PE Advising Ltd | Administrative & support | 2020 |
| Peaceable Care Services Limited | Health & social care | 2022 |
| Peak Summit Properties Ltd | Real estate | 2024 |
| Peak Trading Limited | Professional & scientific | 2008 |
| Peakbridge Growth II Carry SPV LLP | | 2022 |
| Pear Training Ltd | Education | 2015 |
| Pearce Compaction Systems Limited | Manufacturing | 1993 |
| Pearce Holdings (Investments) Limited | Financial services | 2017 |
| Pearce Holdings ST Albans Limited | Financial services | 1994 |
| Pearce Waste Paper Company Limited | | 1982 |
| Pearl & Diamond Ltd | Real estate | 2019 |
| Pearl Clinic Ltd | Other services | 2024 |
| Pearlescent Perfection Ltd | Arts & recreation | 2026 |
| Pearlie Property Services Ltd | Construction | 2019 |
| Pearonline Limited | Information & communication | 2006 |
| Peartree Horticulture Ltd | Administrative & support | 2018 |
| Pedrico Ltd | Hospitality | 2026 |
| Pedro Building Ltd | Construction | 2019 |
| PEER2PEER Global Limited | Administrative & support | 2017 |
| Peerless AV Limited | Wholesale & retail | 1992 |
| PEGASUS7 Limited | Professional & scientific | 2012 |
| Pelican Property Limited | Financial services | 2018 |
| Pelissier Consulting Ltd | Information & communication | 2025 |
| Pellucid Platform Limited | Administrative & support | 2026 |
| PEN Consultancy Limited | Health & social care | 2014 |
| Penacre Flat Management Company Limited | Households | 1979 |
| Pendeza Limited | Wholesale & retail | 2010 |
| Pendix Media Ltd | Administrative & support | 2026 |
| Pendley Developments Limited | Construction | 2024 |
| Pendley HAY Limited | Agriculture & fishing | 2022 |
| Pendley Properties Limited | Real estate | 2014 |
| Pendley Rentals Limited | Real estate | 2021 |
| Penning Enterprises Ltd | Wholesale & retail | 2021 |
| People Xxiv Ltd | Administrative & support | 2016 |
| Peopleytics Ltd | Professional & scientific | 2017 |
| Pepe Grips Ltd | Information & communication | 2023 |
| Pepp's Plumbing & Heating Ltd | Construction | 2020 |
| Pepper and Phillips Limited | Other services | 1998 |
| Pepper Engineering Ltd | Manufacturing | 2016 |
| PER Tutti Limited | Hospitality | 2016 |
| Percy Ingle Bakeries Limited | Manufacturing | 1957 |
| Percy Ingle Employee Services LLP | | 2012 |
| Perdial Limited | Information & communication | 2001 |
| Perfect Timed Goods Ltd | Wholesale & retail | 2023 |
| Perform CS Limited | Administrative & support | 2020 |
| Performance Engineered Supplements Ltd | Wholesale & retail | 2018 |
| Performing Herts Ltd | Education | 2025 |
| Peri Peri ST Albans Limited | Administrative & support | 2017 |
| Peridot Management Solutions Limited | Information & communication | 2012 |
| Perisso Labs Limited | Information & communication | 2026 |
| Perles Ltd | Information & communication | 2016 |
| Permitpath Ltd | Professional & scientific | 2025 |
| Perspico Data Ltd | Professional & scientific | 2025 |
| Perusus Limited | Information & communication | 2015 |
| PES Group Limited | Wholesale & retail | 1993 |
| Pet Bath & Beyond Ltd | Administrative & support | 2016 |
| Peter & Mariya Ltd | Administrative & support | 2011 |
| Peter Badcock (Motor Servicing) Limited | Transport & logistics | 1975 |
| Petits Escargots Childcare Ltd | Education | 2024 |
| Petra Property Ltd | Real estate | 2017 |
| Pevijure Limited | Professional & scientific | 1963 |
| PFL Group Limited | Administrative & support | 2021 |
| PFL Sports Limited | Arts & recreation | 2026 |
| PGS Bygga Limited | Wholesale & retail | 2025 |
| PGS Care Ltd | Health & social care | 2018 |
| PGW Estates Limited | Real estate | 2006 |
| PH Qulture Ltd | Information & communication | 2024 |
| PH Somerset Limited | Administrative & support | 2019 |
| Phab Design Ltd | Professional & scientific | 2016 |
| Pharmastrat Ltd. | Professional & scientific | 2009 |
| Pharmsolutions Ltd | Health & social care | 2018 |
| Phase Seven Services Ltd | Real estate | 2020 |
| PHG Limited | Construction | 2008 |
| Phil Anderson Limited | Professional & scientific | 2010 |
| Phil Tozer Coloproctology Limited | Health & social care | 2017 |
| Phil Wilkins Ltd | Construction | 2023 |
| Philip Adams Music Limited | Arts & recreation | 2013 |
| Philip Callan Associates Limited | Professional & scientific | 2012 |
| Philip Rees Ltd | Professional & scientific | 2003 |
| Phillips Project Delivery Limited | Professional & scientific | 2015 |
| Phillips Property Renovations Ltd | Construction | 2018 |
| Philosophy Ltd | Manufacturing | 2023 |
| Phoenix Barber Co. Limited | Hospitality | 2012 |
| Phoenix Commercial Catering Equipment Limited | Manufacturing | 2006 |
| Phoenix Competitions Ltd | Arts & recreation | 2025 |
| Phoenix Interiors (Hertfordshire) Limited | Wholesale & retail | 2015 |
| Phoenix Lounge (Herts) Ltd | Other services | 2013 |
| Phoenix Sun Limited | Administrative & support | 2022 |
| Photiades Ltd | Professional & scientific | 2012 |
| Photographic Synergy Events Limited | Arts & recreation | 2012 |