| Pavilion Gardens (Aston Clinton) Management Company Limited | Households | 2010 |
| Pcsl Limited | Information & communication | 2019 |
| Pearse Bros Limited | Construction | 2003 |
| Pearsonality Ltd | Information & communication | 2025 |
| Pelko Limited | Information & communication | 2023 |
| Pen-Avia Limited | Transport & logistics | 2004 |
| Pendley Aviation LLP | | 2003 |
| Pendley Beeches Developments Ltd | Construction | 2021 |
| Pendley Day Nursery Limited | Health & social care | 2020 |
| Pendry Mortgage Solutions Limited | Financial services | 2016 |
| Penny Farm Stud Ltd | Agriculture & fishing | 2022 |
| Pentagon Networks Ltd | Information & communication | 2017 |
| Pepper Events Limited | Arts & recreation | 1997 |
| Perfection Automotive Ltd | Wholesale & retail | 2013 |
| Performance Adhesives Limited | Wholesale & retail | 2012 |
| Perrers Partners Ltd | Professional & scientific | 2026 |
| Persuasion Skills Limited | Professional & scientific | 2006 |
| Pescatore Consulting Ltd | Information & communication | 2020 |
| Peter Johnson Management Services Ltd | Construction | 1984 |
| Petra Forma Ltd | Professional & scientific | 2025 |
| PFK Fabrications Ltd | Manufacturing | 2024 |
| PGC Consulting Ltd | Information & communication | 2022 |
| Phase Holdings | Financial services | 2018 |
| Philip Murray Flooring Limited | Construction | 2023 |
| Phillips Build (UK) Ltd | Construction | 2003 |
| Phillips Rentals Ltd | Real estate | 2024 |
| Phit Consultancy Limited | Information & communication | 2006 |
| Phoenix EGG Ltd | Information & communication | 2014 |
| Physical Diversity Limited | Other services | 2017 |
| Physical Therapies Ltd | Other services | 2022 |
| Pictons Solicitors LLP | | 2004 |
| Piggeries Limited | Wholesale & retail | 2008 |
| PIN High Productions Ltd | Information & communication | 2025 |
| Pinctada Ltd | Administrative & support | 2021 |
| Pippa Bolton Creative Ltd | Professional & scientific | 2020 |
| PIX Party Pods Limited | Professional & scientific | 2024 |
| Pixel Bits Limited | Information & communication | 2018 |
| PJ Class 1 Driving Services Ltd | Transport & logistics | 2019 |
| PJD Advisory Ltd | Professional & scientific | 2023 |
| Pjjl International Limited | Professional & scientific | 2021 |
| PJK7 Consulting Ltd | Real estate | 2024 |
| PJM IT Solutions Ltd | Information & communication | 2019 |
| Pjra Consulting Ltd | Information & communication | 2015 |
| Platinum Gymnastics Limited | Arts & recreation | 2016 |
| Pmark LLP | | 2011 |
| PN Consultancy Limited | Information & communication | 2024 |
| Pnimio Ltd | Information & communication | 2016 |
| Portfoleyo Ltd | Information & communication | 2023 |
| Portu Gallo's Ltd | Hospitality | 2014 |
| Posh Sets Limited | Administrative & support | 2015 |
| Poshtrucking Limited | Transport & logistics | 2021 |
| Posting House Management Company Limited | Real estate | 2001 |
| Potash Farm (Management) Limited | Households | 2002 |
| Potter Financial Partners Ltd | Professional & scientific | 2021 |
| Power and Energy Monitors Limited | Professional & scientific | 2012 |
| Practical Strategic Management Limited | Financial services | 2019 |
| Prescription Marketing Ltd | Professional & scientific | 2008 |
| Prestige Management Company Limited | Real estate | 2010 |
| Primary Code Limited | Information & communication | 2010 |
| Prime 5 Consulting Ltd | Professional & scientific | 2011 |
| Prism Projects Ltd | Professional & scientific | 2018 |
| Prizez Ltd | Information & communication | 2026 |
| Proactive Product Solutions Ltd | Information & communication | 2024 |
| Proactive Technical Training Limited | Extraterritorial | 2004 |
| Proctimise Limited | Professional & scientific | 2019 |
| Prodtech Resourcing Ltd | Administrative & support | 2018 |
| Product Safety Collective Limited | Professional & scientific | 2025 |
| Professional Active Software Solutions Ltd | Information & communication | 2019 |
| Professional Apartment Solutions Ltd | Real estate | 2019 |
| Professional Construction Services Ltd | Professional & scientific | 2023 |
| Professional Exchange Ltd | Information & communication | 2005 |
| Professional Independent Services Limited | Professional & scientific | 2023 |
| Professional Solutions Group Limited | Real estate | 2019 |
| Professional Venue Solutions Limited | Administrative & support | 2003 |
| Profinish PAINTERS4YOU Ltd | Construction | 2024 |
| Project 3:23 Limited | Information & communication | 2024 |
| Project Dragonfire Ltd | Information & communication | 2018 |
| Project Number 5 Ltd | Wholesale & retail | 2021 |
| Projectum Limited | Information & communication | 2010 |
| Promansis Limited | Real estate | 2010 |
| Propart Interiors Limited | Construction | 2001 |
| Propeller Procurement Ltd | Professional & scientific | 2022 |
| Protea Analytics Ltd | Information & communication | 2025 |
| Prototipo Design Ltd | Professional & scientific | 2018 |
| PSM Productions Limited | Arts & recreation | 2024 |
| Psychotherapy Space Ltd | Health & social care | 2014 |
| Public Utilities Building Hardware Limited | Wholesale & retail | 2011 |
| Pulse Accountants Ltd | Professional & scientific | 2008 |
| Purefibre Internet Limited | Information & communication | 2015 |
| Purposeai Ltd | Information & communication | 2022 |
| Purssell & Randall Mechanical Services Ltd | Construction | 2015 |
| Pxmedia Limited | Information & communication | 2009 |
| Pxparfait Studio Ltd | Information & communication | 2025 |
| P’S Trims Ltd | Other services | 2026 |
| Qinetix Corporation Ltd | Wholesale & retail | 2026 |
| Qualis Advisors Ltd | Professional & scientific | 2019 |
| Quartz Energy Limited | Manufacturing | 2001 |
| QUERY7 Ltd | Professional & scientific | 2023 |
| Quilter's Legacy Foundation Limited | Health & social care | 2020 |
| Quinden Properties Limited | Real estate | 2024 |