| OUR Pet Village Ltd | Wholesale & retail | 2023 |
| OUR Town Property Limited | Real estate | 2005 |
| Ourthing Global Entertainment Limited | Information & communication | 2022 |
| Ourthing Global MT Limited | Transport & logistics | 2025 |
| Outdone Gardens Limited | Wholesale & retail | 2026 |
| Outfit Create Limited | Professional & scientific | 2009 |
| Outlook Venture Limited | Health & social care | 2009 |
| Outperformance Coaching Limited | Professional & scientific | 2016 |
| Outside Capital Limited | Professional & scientific | 2022 |
| Ouzil Ltd | Manufacturing | 2024 |
| OV Delivery Ltd | Transport & logistics | 2024 |
| Over the Line Consultants Ltd | Professional & scientific | 2019 |
| Overadjust Limited | Professional & scientific | 1992 |
| Overclock Retail Ltd | Wholesale & retail | 2026 |
| Overdog.Ai Ltd | Professional & scientific | 2023 |
| Overguard Security Limited | Administrative & support | 2024 |
| OVI Transport Ltd | Transport & logistics | 2018 |
| OVIDIU92 Ltd | Transport & logistics | 2025 |
| Owcha Ltd | Information & communication | 2025 |
| Owen Nutrition Limited | Wholesale & retail | 2025 |
| Owers Consulting Limited | Professional & scientific | 2014 |
| OWL EYE Group UK Ltd | Construction | 2022 |
| OX Properties and Lettings Ltd | Real estate | 2024 |
| Oxford House (Earls Colne) Management Company Ltd | Real estate | 2025 |
| Oxford Road (Colchester) Management Company Limited | Households | 1987 |
| Oxley Brickwork Limited | Construction | 2021 |
| OYE 3G Construction Ltd | Construction | 2025 |
| Oyster Art & Books Ltd | Hospitality | 2013 |
| Oyster Place Management Limited | Households | 2012 |
| Oysters and ALE Limited | Hospitality | 2008 |
| Ozivel Limited | Real estate | 2022 |
| Ozome Radiology Ltd | Health & social care | 2018 |
| P & D Property Group Ltd | Real estate | 2024 |
| P & K Transport Limited | Transport & logistics | 2017 |
| P & L & MCS Limited | Real estate | 2009 |
| P & N Vehicle Body Repairs Limited | Wholesale & retail | 2006 |
| P & R Chambers Limited | Construction | 2001 |
| P & S Automation Limited | Manufacturing | 1993 |
| P & T Frizzell Assets Ltd | Administrative & support | 2012 |
| P & Y Investments Ltd | Hospitality | 2024 |
| P B Risk Administration Limited | Financial services | 2004 |
| P C G Properties Limited | Real estate | 2013 |
| P Fenton Ltd | Hospitality | 2002 |
| P Gibbins Ltd | Hospitality | 2023 |
| P Green & SON Limited | Information & communication | 2017 |
| P H Taxi Services Ltd | Wholesale & retail | 2023 |
| P J D Horse Transport Limited | Transport & logistics | 2025 |
| P J Forbes Limited | Professional & scientific | 2009 |
| P J Gavin Ltd | Construction | 2015 |
| P J H Consultancy Limited | Real estate | 2006 |
| P J Homewood Ltd | Information & communication | 2008 |
| P J Services (UK) Limited | Professional & scientific | 2004 |
| P James Engineering Ltd | Construction | 2013 |
| P Limited | Construction | 2003 |
| P M R Painting and Decorating Limited | Construction | 2015 |
| P R Construction Essex Limited | Construction | 2014 |
| P R Sports Hub 1 Limited | Professional & scientific | 2026 |
| P Squeak Limited | Real estate | 2012 |
| P W R Accountants Limited | Professional & scientific | 2010 |
| P Webb Limited | Construction | 2021 |
| P&B Supermarket Ltd | Wholesale & retail | 2025 |
| P&D Properties (SE) Ltd | Real estate | 2022 |
| P&F Property Ltd | Construction | 2021 |
| P&P Corporation Ltd | Hospitality | 2025 |
| P&S.S.C Limited | Professional & scientific | 2017 |
| P. & T. Winter Limited | | 1965 |
| P. Gibson Ltd | Construction | 2002 |
| P. J. Cars & Plant Limited | Real estate | 1956 |
| P.C.S. (Projects) Limited | Construction | 2003 |
| P.D. Construction & Development Ltd | Construction | 2006 |
| P.G. Oxley Limited | Professional & scientific | 1991 |
| P.G. RIX (Farms) Limited | Agriculture & fishing | 1964 |
| P.H. Contract Services Limited | Administrative & support | 1994 |
| P.H.Emporium Ltd | Wholesale & retail | 2017 |
| P.J.H. Properties Limited | Real estate | 2002 |
| P.L.O.T. Community Interest Company | Education | 2017 |
| P.M. Electrical Essex Ltd | Construction | 2017 |
| P.W. Body Repairs Ltd | Wholesale & retail | 2017 |
| P24 Ltd | Health & social care | 2022 |
| P2P Education Ltd | Education | 2018 |
| P7 Development Ltd | Professional & scientific | 2022 |
| Paathshala - Supporting Special Journeys Ltd | Education | 2024 |
| PAB Properties (Ipswich) Ltd | Real estate | 2005 |
| PAB Technical Solutions Ltd | Professional & scientific | 2025 |
| Pace Accountancy Ltd | Professional & scientific | 2011 |
| Pace Consult Limited | Real estate | 2006 |
| Pace Security Solutions Ltd | Administrative & support | 2021 |
| Paceautomotive Body Repairs Limited | Wholesale & retail | 2016 |
| Pacemed Global Services Limited | Construction | 2018 |
| Pach Holdings Ltd | Professional & scientific | 2020 |
| Pacific (BC) Bidco Limited | Professional & scientific | 2016 |
| Pacific (BC) Hedgeco Limited | Professional & scientific | 2016 |
| Pacific (BC) Topco 2 Limited | Professional & scientific | 2016 |
| Pacific (BC) Topco 3 Limited | Professional & scientific | 2016 |
| Pacific (BC) Topco 4 Limited | Professional & scientific | 2016 |
| Pacific (BC) Topco 5 Limited | Professional & scientific | 2016 |
| Packers and Shims Ltd | Extraterritorial | 2018 |
| Packpal Limited | Administrative & support | 2009 |
| PAD Landscape Essex Ltd | Administrative & support | 2025 |
| Paddock Management Company (Woodley) Limited | Real estate | 2015 |