| Opus Durum Recruitment Consultancy Limited | Administrative & support | 2015 |
| Orchard SIX Limited | Real estate | 2025 |
| Orchid Medicine Ltd | Health & social care | 2021 |
| Oriel Consulting Limited | Information & communication | 2023 |
| Osotech Ltd | Information & communication | 2014 |
| Osteopathics Limited | Health & social care | 2016 |
| Ostop Solutions Limited | Information & communication | 2022 |
| Overboard Supplies Limited | Wholesale & retail | 2018 |
| Oxford Media & Medicine Limited | Professional & scientific | 2011 |
| P L Financial Consultants Limited | Administrative & support | 1999 |
| P'S Casas Limited | Real estate | 2022 |
| P.C. Plumbing Limited | Construction | 2007 |
| Paddock View Management Company Limited | Households | 2011 |
| Padelito Ltd | Arts & recreation | 2026 |
| Paecl Ltd | Real estate | 2026 |
| Page Place Ltd | Real estate | 2022 |
| Paladin Exotic Beverages Limited | Wholesale & retail | 2021 |
| Palatine Services Limited | Administrative & support | 2017 |
| PAM Analytics Ltd | Information & communication | 2016 |
| Parallax Films Limited | Information & communication | 2025 |
| Parfums Xavier Laurent Limited | Extraterritorial | 2025 |
| Park Lane Logistics Ltd | Transport & logistics | 2024 |
| Parker Design Engineering Limited | Administrative & support | 2002 |
| Partisan Holdings Ltd | Real estate | 2017 |
| Pathfinder Retail Ltd | Wholesale & retail | 2026 |
| Pathway Capital Limited | Financial services | 2023 |
| Pathway Leisure Limited | Arts & recreation | 2023 |
| PAW Behaviour Dog Training Ltd | Education | 2026 |
| Pawnbroking Systems Ltd | Information & communication | 2011 |
| Paxton Private Finance LLP | | 2010 |
| Paxton Property Finance Ltd | Financial services | 2015 |
| PB India Consulting Limited | Professional & scientific | 2023 |
| Pembury Accountants Limited | Professional & scientific | 2018 |
| Pemk Ltd | Transport & logistics | 2015 |
| Pension Investment Academy Limited | Extraterritorial | 2010 |
| People Skill Unite Ltd | Administrative & support | 2023 |
| Perfume Playground Limited | Wholesale & retail | 2020 |
| Peter Alexander Investments Limited | Financial services | 2015 |
| Peter Hartnell (Precious Metals) Limited | Manufacturing | 1986 |
| Peter Hartnell Precious Metals Holdings Limited | Manufacturing | 2026 |
| Pg-Ag Services Limited | Construction | 2017 |
| PGP Media Limited | Other services | 2007 |
| Pharmasearch Limited | Administrative & support | 2010 |
| Pharmorshe Limited | Information & communication | 2014 |
| Phoenix Communications (UK) Limited | Professional & scientific | 2009 |
| Pitsmead Properties Ltd | Real estate | 2026 |
| PJM Props Limited | Administrative & support | 2023 |
| PKM Financial Solutions Ltd | Professional & scientific | 2019 |
| Plant Projects Limited | Administrative & support | 2010 |
| Platinum Luxury Travel Ltd | Transport & logistics | 2026 |
| Plurality Services Limited | Professional & scientific | 2008 |
| PNM 5 Investments Limited | Financial services | 2022 |
| PNM 5 Services Limited | Financial services | 2022 |
| Pocketeye Limited | Health & social care | 2022 |
| POD Linen Limited | Wholesale & retail | 2016 |
| Policymogul Limited | Professional & scientific | 2017 |
| Ponder Street Management (Leeds) Ltd | Real estate | 2024 |
| Ponder Street Management Co Limited | Real estate | 2005 |
| Poole Wealth Management Ltd | Financial services | 2023 |
| Poppy Academy Trust | Education | 2015 |
| Porters Park Golf Club Limited | Arts & recreation | 2022 |
| Portfolio Williams Ltd | Real estate | 2017 |
| POS Deliveries Limited | Hospitality | 2025 |
| Pouty Lipzz Limited | Wholesale & retail | 2014 |
| Power Supplies Limited | Wholesale & retail | 2014 |
| Pratibha Mistry Ltd | Public administration | 2013 |
| Prestige Chauffeur London Ltd | Transport & logistics | 2025 |
| Pretone Ltd | Other services | 2018 |
| Prime Guard Protection Ltd | Administrative & support | 2025 |
| Private Driven Chauffeur Ltd | Transport & logistics | 2024 |
| Procare Small Works and Finishing Ltd | Construction | 2021 |
| Product Driven Limited | Other services | 2010 |
| Promedia Accountancy Ltd | Professional & scientific | 2011 |
| Properties of Style Limited | Real estate | 2005 |
| Property Investment Partnership Limited | Real estate | 1992 |
| Property Plain & Simple Limited | Other services | 2012 |
| Property Trader Investments Limited | Real estate | 2015 |
| Proudly Naija Souk Ltd | Wholesale & retail | 2022 |
| Psychology & Group Analytic Consultancy Ltd | Health & social care | 2023 |
| Psychology Expert (UK) Limited | Health & social care | 2011 |
| Purely Personalised Limited | Wholesale & retail | 2016 |
| Purestate Ltd | Real estate | 2025 |
| Purple Zebra Trading Limited | Information & communication | 2021 |
| PW Watches Ltd | Manufacturing | 2026 |
| Pycombe Properties Ltd | Real estate | 2020 |
| Pypers LEA Estate Ltd | Real estate | 2020 |
| Q Clothing Company Limited | Wholesale & retail | 2012 |
| Quexil Ltd | Information & communication | 2023 |
| R G Plumbing & Heating Services Ltd | Construction | 2015 |
| R.A. Sparks Ltd | Construction | 2023 |
| Racecar New Media Services Limited | Information & communication | 1996 |
| Rachel Paterson Limited | Professional & scientific | 2019 |
| Radia Rocket Limited | Information & communication | 2020 |
| Radlett (High Firs) Limited | Households | 1985 |
| Radlett Cricket Club (Services) Limited | Arts & recreation | 2011 |
| Radlett Cricket Club Limited | Arts & recreation | 2003 |
| Radlett DRY Cleaners Ltd | Other services | 2024 |
| Radlett FC Ltd | Wholesale & retail | 2024 |
| Radlett Fish & Chips Ltd | Wholesale & retail | 2024 |
| Radlett Golf Centre Limited | Arts & recreation | 2026 |