| Optimal Heating Services Limited | Construction | 2015 |
| Optimal Nutrition Services Ltd | Health & social care | 2023 |
| Optimax AI Ltd | Professional & scientific | 2024 |
| Opus CT Bay Tree RTM Company Ltd | Households | 2025 |
| OPV Limited | Real estate | 1988 |
| Oracle Energy Services Ltd | Construction | 2020 |
| Oracle PR Limited | Professional & scientific | 2011 |
| Oral and Facial Surgery Ltd | Health & social care | 2010 |
| Orbhawk Limited | Extraterritorial | 1989 |
| Orbi CMI Ltd | Information & communication | 2026 |
| Orchard Farm Redhill Residents Mgmt. Co. Ltd | Real estate | 2024 |
| Orchard House Capital Ltd | Wholesale & retail | 2016 |
| Orchard House Professional Services Ltd | Professional & scientific | 2023 |
| Orchid Systems Limited | Wholesale & retail | 2005 |
| Ordinary People (OP) Ltd | Information & communication | 2025 |
| Orgste Ltd | Professional & scientific | 2025 |
| Oriental Grocery Ltd | Wholesale & retail | 2019 |
| Orpington Chinese Language School Epsom Ltd | Education | 2023 |
| Orra Creative Limited | Professional & scientific | 2019 |
| Oryx Catering Group Ltd | Hospitality | 2025 |
| Osare.Io Limited | Wholesale & retail | 2020 |
| Osas Enterprises Limited | Health & social care | 2013 |
| Osborne Housing Ltd | Real estate | 2019 |
| Osborne Place Management Company Limited | Households | 1979 |
| OSD Investments Ltd | Financial services | 2010 |
| Oshi Group Ltd | Financial services | 2024 |
| Osih Contracts Limited | Administrative & support | 2019 |
| Osteocare International Limited | Professional & scientific | 2002 |
| Osteria Dell' Angolo Limited | Hospitality | 2007 |
| Otafilms Ltd | Information & communication | 2011 |
| OUT of the Dark Consulting Limited | Information & communication | 2008 |
| OVA Projects UK Ltd | Professional & scientific | 2025 |
| Over the Jumps Racing Ltd | Arts & recreation | 2025 |
| Over the Rainbow Education Ltd | Education | 2019 |
| Owen Advisory Services Limited | Professional & scientific | 2025 |
| Owen Smith Coaching & Consulting Ltd | Professional & scientific | 2025 |
| OWL and Snake Immigration Ltd | Other services | 2021 |
| Oxford House (Wimbledon) Management Company Limited | Households | 1995 |
| Oxshott Golf Limited | Real estate | 2022 |
| Oxshott Properties Limited | Real estate | 2019 |
| Oyster Barbers Ltd | Other services | 2023 |
| OZ Design Ltd | Professional & scientific | 2005 |
| OZ Pilates Ltd | Arts & recreation | 2025 |
| Ozscot Miner Limited | Professional & scientific | 2025 |
| O’Korefe Property Investments Ltd | Real estate | 2025 |
| P & G Motors 2 Ltd | Wholesale & retail | 2025 |
| P & I Broadcast Limited | Information & communication | 2009 |
| P & P Contracting Limited | Financial services | 2007 |
| P & S Cladding Consultants Limited | Professional & scientific | 2026 |
| P and P Active Limited | Wholesale & retail | 2009 |
| P C Walker Motor Engineers Limited | Wholesale & retail | 2008 |
| P I Window Cleaning Ltd | Administrative & support | 2026 |
| P K ALL Access Platforms Ltd | Construction | 2014 |
| P K Mechanical Property Ltd | Real estate | 2025 |
| P&G Project Management Ltd | Construction | 2022 |
| P&P Consultancy Ltd | Professional & scientific | 2024 |
| P&Q Global Ltd | Wholesale & retail | 2023 |
| P&R Associates Ltd | Information & communication | 2015 |
| P.Johnson Civils Ltd | Construction | 2024 |
| P.K Blinders Construction Ltd | Construction | 2020 |
| P2OJX Limited | Professional & scientific | 2025 |
| P3N IT Consulting Limited | Information & communication | 2014 |
| PA UK Services Limited | Real estate | 2023 |
| PAC Tuning Ltd | Other services | 2025 |
| Pace Holdings Limited | Information & communication | 2020 |
| Packaging Options Ltd | Administrative & support | 2024 |
| Packfords Residential Ltd | Real estate | 2022 |
| PAD Living Limited | Real estate | 2025 |
| Padel London Ltd | Arts & recreation | 2020 |
| Page Bodyshops Limited | Wholesale & retail | 2016 |
| Page Holdings Limited | Construction | 1978 |
| Page Motors (Epsom) Limited | Real estate | 1933 |
| Page Storage Ltd | Administrative & support | 2025 |
| Paget Place Management Company Limited | Households | 1987 |
| Paige Elliott Trading Ltd | Wholesale & retail | 2025 |
| Paisley Park Consulting Ltd | Administrative & support | 2023 |
| PAL TA Catering Services Ltd | Hospitality | 2020 |
| Pale DOT Ltd | Professional & scientific | 2021 |
| Pale Heretic Limited | Information & communication | 2005 |
| Pallet Innovation Labs Ltd | Information & communication | 2023 |
| Panalogic Limited | Information & communication | 2012 |
| Pangea Welding Ltd | Construction | 2020 |
| Panger Limited | Financial services | 2024 |
| Panitek Power Limited | Professional & scientific | 2020 |
| Pankan Ltd | Other services | 2012 |
| Panther Creative Limited | Administrative & support | 2013 |
| Papagram Developments Ltd | Construction | 2018 |
| Paper Free Solutions Limited | Information & communication | 2000 |
| Paprika (GB) Limited | Hospitality | 2014 |
| Paradeem Developments Ltd | Real estate | 2014 |
| Paradox Sporting Goods Ltd | Wholesale & retail | 2026 |
| Parah Management Investment Limited | Financial services | 2022 |
| Parallel Contemporary Art Limited | Administrative & support | 2010 |
| Parallel Live Group Limited | Administrative & support | 2015 |
| Parallel Media Group Ltd | Administrative & support | 2018 |
| Parallel Medos Group Limited | Financial services | 1998 |
| Paramount Management Global Limited | Professional & scientific | 2012 |
| Parcello Ltd | Transport & logistics | 2022 |
| Parchmore Road Property Management Company Limited(The) | Real estate | 1965 |
| Pareto Consultancy and Training Ltd. | Professional & scientific | 2012 |