| NM Mayfair Limited | Construction | 2024 |
| Nmar Property Ltd | Real estate | 2020 |
| Nobleworth Ltd | Financial services | 2017 |
| Nokaronline Limited | Wholesale & retail | 2020 |
| Nomuro Nominees U.K. Ltd | Construction | 2021 |
| Northfield Care Limited | Health & social care | 2008 |
| Nova Casa Ltd | Construction | 2024 |
| Novus Contractors Ltd | Construction | 2018 |
| Nuco Solutions Ltd | Information & communication | 2014 |
| Nuvira Earth Systems Ltd | Manufacturing | 2025 |
| NUW Ltd | Information & communication | 2023 |
| NYA Health AYU International Ltd | Professional & scientific | 2024 |
| Nylaplas Engineering Limited | Manufacturing | 1982 |
| O Dara Services Limited | Health & social care | 2020 |
| O'Raghallaigh & Co Ltd | Other services | 2026 |
| Oak Tree Field Holdings Limited | Financial services | 2020 |
| Oak Wood Aviation Consultancy Ltd | Professional & scientific | 2016 |
| Oaknest Holdings Ltd | Professional & scientific | 2025 |
| OCB Manual Therapy Services Limited | Health & social care | 2000 |
| Occasions by Rash Ltd | Hospitality | 2024 |
| Octavia Jewellery Limited | Wholesale & retail | 2018 |
| Ohlin & Partners Ltd | Professional & scientific | 2016 |
| Olayinka Egbaiyelo Ltd | Other services | 2015 |
| Old School (Longcross) Ltd | Wholesale & retail | 2001 |
| Old Town Roofing and Building Company Ltd | Construction | 2020 |
| Oliver Drake Plumbing & Heating Limited | Construction | 2011 |
| Oliver Francis Limited | Wholesale & retail | 2026 |
| Olumar Properties Ltd | Real estate | 2019 |
| OMC Engineering Ltd | Construction | 2026 |
| Omega Architects Limited | Professional & scientific | 1994 |
| Omega Partnership Holdings Limited | Financial services | 2018 |
| Omya Performance Polymer Distribution Holdco UK Limited | Financial services | 2021 |
| Onceamonthcleaning Ltd | Administrative & support | 2017 |
| One Stronsa Road Limited | Real estate | 2005 |
| Onesophical Limited | Information & communication | 2019 |
| Online Sessions Ltd | Arts & recreation | 2012 |
| Opti Hy-Design Consultants Limited | Financial services | 2022 |
| Optimal Fencing Ltd | Extraterritorial | 2020 |
| Optimar Consulting Services Limited | Professional & scientific | 2025 |
| Opus Auctions (UK) Limited | Wholesale & retail | 2017 |
| Orange Tree Surrey Limited | Administrative & support | 2021 |
| Orchid Interpretation Ltd | Mining & quarrying | 2021 |
| Originwolf Limited | Wholesale & retail | 2018 |
| Orthopaedic Advances Limited | Health & social care | 2003 |
| Ortus Developments Limited | Real estate | 2021 |
| Oscar Business Solutions Limited | Financial services | 2012 |
| OSR IT Solutions Ltd | Information & communication | 2019 |
| Oswald Lord Ltd | Real estate | 2025 |
| Othen Services Ltd | Administrative & support | 2024 |
| Ottershaw Chertsey Ltd | Hospitality | 2019 |
| Ottershaw Community Partnership Community Interest Company | Arts & recreation | 2012 |
| OUT There Trees Ltd | Agriculture & fishing | 2010 |
| Outcomms Ltd | Professional & scientific | 2015 |
| Outer City Developments Limited | Manufacturing | 2025 |
| Outer City Flooring Limited | Construction | 2025 |
| Outlook Windows Limited | Construction | 1998 |
| Overcomeoverthinking Limited | Information & communication | 2021 |
| Ozone Clean Air Limited | Administrative & support | 2009 |
| P Dibden Services Ltd | Information & communication | 2012 |
| P J Stoker Limited | Health & social care | 2017 |
| P T Advocate Ltd | Professional & scientific | 2022 |
| P&R Convenience Ltd | Wholesale & retail | 2024 |
| P.A.S.S Football Management Limited | Arts & recreation | 2026 |
| P1 Carbon Solutions Ltd. | Professional & scientific | 2018 |
| Page & Rodgers Estate Agents Limited | Real estate | 2005 |
| Pannells Farm Limited | Agriculture & fishing | 2013 |
| Papcorp Holdings Ltd | Real estate | 2018 |
| Pappaya Cloud Limited | Information & communication | 2019 |
| Pappaya Edumarket Limited | Information & communication | 2020 |
| Pappaya Sign Limited | Information & communication | 2020 |
| Paquedale Consulting Ltd | Professional & scientific | 2022 |
| Paragone NFT Limited | Wholesale & retail | 2016 |
| Paramount Properties London Limited | Real estate | 2014 |
| Parasol Music Limited | Manufacturing | 2023 |
| Parasol Records Limited | Manufacturing | 2023 |
| Park West Estates Limited | Real estate | 2024 |
| Parker Transport Services Ltd | Transport & logistics | 2018 |
| Passion 4 Health International Limited | Manufacturing | 1997 |
| Passion Recruitment Agency Limited | Health & social care | 2017 |
| PASSION4CHEESES Ltd | Manufacturing | 2020 |
| PAT Cotter Coating Services Ltd | Construction | 2025 |
| Patiala OFF Licence Limited | Wholesale & retail | 2012 |
| Patients 1ST Services Ltd | Administrative & support | 2021 |
| Patterson Products Holdings Ltd | Financial services | 2019 |
| Patterson Products Limited | Manufacturing | 2002 |
| Paul Kennett Engineering Ltd | Administrative & support | 2008 |
| Paulo Silva Transporte (UK) Ltd. | Wholesale & retail | 2024 |
| Pawsome Place Doggy Daycare Ltd | Agriculture & fishing | 2023 |
| Payamungrai Ltd | Hospitality | 2018 |
| PBM Tech Ltd | Wholesale & retail | 2024 |
| PCG Consultants Limited | Administrative & support | 2011 |
| Peak District Coffee Company Limited | Hospitality | 2014 |
| Penton Community and Social Club Limited | Other services | 2004 |
| Penton Craning Limited | Professional & scientific | 2007 |
| Penton Park Trading Limited | Other services | 2007 |
| Perch Marketing Ltd | Professional & scientific | 2014 |
| Performance Automotive Parts Ltd | Information & communication | 2024 |
| Performance Parts Distribution Ltd. | Wholesale & retail | 2013 |
| Pet Centre Limited | Extraterritorial | 2021 |
| Petrow Estates Limited | Construction | 2008 |