| Primrose Company Secretaries Limited | Extraterritorial | 2014 |
| Principal Cleaning Solutions Ltd | Administrative & support | 2022 |
| Principal Climate Technologies Limited | Energy | 2018 |
| Principle Defence Ltd | Information & communication | 2021 |
| Priory View Hitchin Management Company Limited | Households | 2006 |
| Pristine Landscapes Ltd | Administrative & support | 2023 |
| Pro Boiler Care Limited | Construction | 2021 |
| Pro Sports Recovery Ltd | Administrative & support | 2022 |
| Pro-Roofers & Builders Limited | Construction | 2025 |
| Pro:Direct Academy Centres Limited | Arts & recreation | 2025 |
| Proactive Services Group Ltd | Information & communication | 2015 |
| Proceed Archiving Solutions Limited | Information & communication | 2005 |
| Process Machinery Limited | Manufacturing | 1978 |
| Prodec Group Services Limited | Construction | 2024 |
| Prodolce Ltd | Wholesale & retail | 2018 |
| Product People Events Limited | Administrative & support | 2023 |
| Production Elite Limited | Arts & recreation | 2025 |
| Professional Home Improvements Local Ltd | Construction | 2024 |
| Professional Vision Services Limited | Administrative & support | 1990 |
| Profleet Parts Limited | Wholesale & retail | 2015 |
| Progabbana Limited | Construction | 2021 |
| Proiekt Ltd | Professional & scientific | 2019 |
| Project 1966 Ltd | Construction | 2021 |
| Project FAB Holdings UK Limited | Real estate | 2024 |
| Project Fabrications (London) UK Limited | Manufacturing | 2011 |
| Project Façade Limited | Construction | 2022 |
| Project-S Developments Limited | Real estate | 2019 |
| Prolase Clinics Ltd | Other services | 2015 |
| Prolific Digital Media Ltd | Information & communication | 2020 |
| Prom to Bride Limited | Wholesale & retail | 2015 |
| Promo Partners Ltd | Information & communication | 2015 |
| Property & Asset Services Ltd | Real estate | 2019 |
| Property Elevator Partnership Ltd | Real estate | 2015 |
| Property Management (Hitchin) Ltd | Professional & scientific | 2016 |
| Property Partners Limited | Extraterritorial | 1999 |
| Property Renovations and Maintenance Ltd | Real estate | 2022 |
| Property Sourcing Experts Ltd | Real estate | 2024 |
| Propfx Ltd | Professional & scientific | 2022 |
| Proquest Limited | Professional & scientific | 1995 |
| Prosanita Healthcare Limited | Administrative & support | 1998 |
| Protego Electrical Ltd | Construction | 2024 |
| Protheros Garage Limited | Wholesale & retail | 2013 |
| Protours Theatre Limited | Other services | 2015 |
| Providence Kitchen Ltd. | Hospitality | 2018 |
| Provident Developments Limited | Extraterritorial | 2012 |
| Provimedisupply Limited | Manufacturing | 2026 |
| Pryors (Pirton) Management Company Ltd | Households | 2019 |
| PSD Logistics Ltd | Other services | 2021 |
| PSF Management Limited | Professional & scientific | 2025 |
| PSJ Shared Limited | Financial services | 2024 |
| Psychesoma Ltd | Other services | 2015 |
| PT Cars Ltd | Administrative & support | 2018 |
| Pthw Properties Ltd | Real estate | 2017 |
| Pubco UK Limited | Hospitality | 2025 |
| Public Sector Contracting Ltd | Administrative & support | 2018 |
| Puccino's AKM Hitchin Ltd | Hospitality | 2020 |
| Punchy Streams Ltd | Information & communication | 2020 |
| Punia Developments Limited | Real estate | 2020 |
| Punia Ltd | Professional & scientific | 2015 |
| Punia Real Estates Ltd | Real estate | 2022 |
| Pure Alignment Ltd | Wholesale & retail | 2025 |
| Pure Inter Ltd | Wholesale & retail | 2019 |
| Pure Stoves & Fireplaces Limited | Wholesale & retail | 2012 |
| Purkco Limited | Financial services | 2026 |
| Purkelly Bros. Limited | Construction | 1974 |
| Purple Reign Ltd | Arts & recreation | 2019 |
| Purple Sphere Ltd | Professional & scientific | 2025 |
| Purple Vigilance Limited | Administrative & support | 2011 |
| PYE TV Limited | Wholesale & retail | 2014 |
| Q Anne Bidco Limited | Financial services | 2018 |
| Q Anne Midco 1 Limited | Financial services | 2018 |
| Q Anne Midco 2 Limited | Financial services | 2018 |
| Q Anne Topco Limited | Financial services | 2018 |
| Qbex Developments Limited | Construction | 2024 |
| QED Aerospace Limited | Administrative & support | 2000 |
| QF Finance Holdings Limited | Financial services | 2024 |
| QKD LLP | | 2018 |
| QP Property Management LLP | | 2023 |
| Qsid Limited | Transport & logistics | 2013 |
| Qualis Pharma Solutions Limited | Professional & scientific | 2021 |
| Quality Pack Tubes Limited | Administrative & support | 2022 |
| Quanticate Limited | Professional & scientific | 2007 |
| Quantum Media Limited | Professional & scientific | 2026 |
| Quantum Peak Holdings Limited | Financial services | 2026 |
| Quantumtech Limited | Information & communication | 2005 |
| Quartertoten Productions Limited | Information & communication | 2010 |
| Qube 2 Limited | Real estate | 2008 |
| Queen B TV Ltd | Other services | 2018 |
| Queens Gate Mews Residents Company Limited | Households | 1998 |
| Quick Clear Drainage Ltd | Water & waste | 2015 |
| Quick-Teck Electronics Limited | Manufacturing | 2015 |
| Quickstride PV Limited | Professional & scientific | 2024 |
| Quirky Limited | Manufacturing | 2024 |
| Quite Good Food and Wine Limited | Hospitality | 2023 |
| Quito 2003 Limited | Financial services | 2024 |
| Quiz Events Ltd. | Arts & recreation | 2006 |
| Qumec Limited | Manufacturing | 2001 |
| Quronix Limited | Information & communication | 2010 |
| R & a Coating Limited | Manufacturing | 1995 |
| R & K Darts Agency Ltd | Professional & scientific | 2020 |