| Progressive Technology Limited | Professional & scientific | 2009 |
| Project Development Company Holdings (PDC) Ltd | Construction | 2019 |
| Project Farm Bidco Limited | Financial services | 2015 |
| Project Roman Midco Limited | Other services | 2024 |
| Project Roman Topco Limited | Other services | 2024 |
| Project Telecom Holdings Limited | Professional & scientific | 1999 |
| Projectled Ltd | Construction | 2022 |
| Projectstrong Ltd | Information & communication | 2018 |
| Promvit Ltd | Wholesale & retail | 2013 |
| Property and Estate Care Solutions Limited | Administrative & support | 2025 |
| Property in Lucca Ltd | Real estate | 2019 |
| PROSPECT4 Limited | Real estate | 2019 |
| Prosperitas Estate Planning Limited | Administrative & support | 2008 |
| Prosphr Solutions Limited | Professional & scientific | 2023 |
| Protean Advanced Limited | Manufacturing | 2018 |
| Protech Consultancy (UK) Limited | Real estate | 2024 |
| Protect and Invest Limited | Professional & scientific | 2005 |
| Proxemis Limited | Other services | 2023 |
| PRT Engineering Limited | Professional & scientific | 2025 |
| Prysm Softech Ltd | Information & communication | 2002 |
| PS Contracting Limited | Professional & scientific | 2008 |
| PS Ventures Limited | Information & communication | 2008 |
| PSL Future Limited | Construction | 2018 |
| PT SKI Limited | Administrative & support | 2010 |
| PUB Marketing Circle Ltd | Hospitality | 2012 |
| Pulleyn Cleaning Services Ltd | Administrative & support | 2002 |
| Pulse Medical UK Ltd | Manufacturing | 2022 |
| Punjabi Virsa Ltd | Hospitality | 2023 |
| Pure Stroke Putting Ltd | Wholesale & retail | 2021 |
| Pure Water Detailing Ltd | Other services | 2017 |
| Purity Food Company Limited | Wholesale & retail | 2024 |
| Purlescence Limited | Wholesale & retail | 2000 |
| Purlnova Limited | Wholesale & retail | 2012 |
| Purple Giraffe Events Ltd | Hospitality | 2022 |
| Purple Mermaid Limited | Information & communication | 2024 |
| Purple Placements Limited | Administrative & support | 2015 |
| Px-Partnership (UK) Limited | Real estate | 2013 |
| Px-Partnership Properties Limited | Real estate | 2013 |
| Px-Partnership UK (Grey) Ltd | Real estate | 2025 |
| Q2C Consultancy Ltd | Information & communication | 2024 |
| QG Property Limited | Real estate | 2026 |
| Qixian Ltd. | Administrative & support | 2012 |
| QS Associates Limited | Professional & scientific | 1999 |
| Quadrabase Limited | Extraterritorial | 2016 |
| Quadrabuild Holdings Limited | Extraterritorial | 2016 |
| Quadrabuild Ltd | Manufacturing | 2005 |
| Quadrafix Limited | Extraterritorial | 2016 |
| Quadrapile Ltd | Extraterritorial | 2013 |
| Quality Caring Limited | Health & social care | 1995 |
| Quantum Partners (Consulting) LLP | | 2011 |
| Quanyx Ltd | Information & communication | 2013 |
| Quarmans Limited | Professional & scientific | 2018 |
| Quayviews Limited | Professional & scientific | 2011 |
| Qube Administration Services Limited | Administrative & support | 2025 |
| Queensmere Estates Limited | Real estate | 1995 |
| Queensmere Properties Limited | Construction | 1955 |
| Questus Consulting Ltd | Professional & scientific | 2012 |
| Quick-Test Technologies Limited | Administrative & support | 2008 |
| Quicklogic Limited | Health & social care | 1986 |
| Quicklogic Properties Limited | Real estate | 2014 |
| Quicksilver Software Limited | Information & communication | 1998 |
| Quin Consulting Limited | Real estate | 2006 |
| Quince Consulting Limited | Professional & scientific | 2010 |
| Quinn Says Ltd | Wholesale & retail | 2023 |
| Quinquin Limited | Water & waste | 2009 |
| Quintons (Commercial) Limited | Administrative & support | 2002 |
| Quintons (Newbury) Limited | Real estate | 1986 |
| Qutrit AI Labs Ltd | Information & communication | 2025 |
| QVS Electrical Supplies Limited | Extraterritorial | 2016 |
| QVS Electrical Wholesale Limited | Extraterritorial | 2016 |
| R & D Caesar Building Contractors Ltd | Construction | 2022 |
| R C Crafts Ltd | Wholesale & retail | 2009 |
| R Hallett Properties Limited | Real estate | 2019 |
| R J Lindeman Ltd | Professional & scientific | 2015 |
| R K C Decorating Limited | Construction | 2004 |
| R K Telecommunications Ltd. | Information & communication | 2013 |
| R P D Services Limited | Information & communication | 2002 |
| R&D Rampton Ltd | Agriculture & fishing | 2020 |
| R-Outcomes Ltd | Professional & scientific | 2014 |
| R.C.Smallbone(Newbury)Limited | Other services | 1959 |
| R.J. Blundy & SON Limited | Transport & logistics | 2003 |
| R.J. Blundy Limited | Transport & logistics | 2003 |
| R.P. Precision Tools Limited | Manufacturing | 1993 |
| RA Precision Limited | Wholesale & retail | 2005 |
| Rabah Limited | Construction | 2016 |
| Racecourse Food & Wine Ltd | Wholesale & retail | 2023 |
| Rachel Cropper Studio Ltd | Professional & scientific | 2017 |
| Rachel Poole Consulting Limited | Information & communication | 2023 |
| Racsostudio Ltd | Wholesale & retail | 2024 |
| Raddec Holdings Ltd | Financial services | 2024 |
| Raddec International Ltd | Manufacturing | 2006 |
| Radiant Films Ltd | Information & communication | 2019 |
| Radnor Close Management Limited | Households | 1972 |
| Radwin Transport Ltd | Transport & logistics | 2015 |
| Railton TPC Ltd | Professional & scientific | 2013 |
| RAJ Taxis Newbury Ltd | Transport & logistics | 2024 |
| Rajaroyjoseph Ltd | Information & communication | 2015 |
| Rampant Cat (Newbury) Limited | Hospitality | 2012 |
| Ramsbury Electrical Limited | Construction | 2015 |
| RAN Expertise Ltd | Professional & scientific | 2015 |