| Orchard Education Ltd | Education | 2018 |
| Orchard Farm Kent Limited | Construction | 2014 |
| Orchard House (Surrey) Management Ltd | Households | 2025 |
| Orchard Leisure Limited | Hospitality | 2000 |
| Orchestrate Project Management Limited | Administrative & support | 2009 |
| Organic Dog Company Ltd | Wholesale & retail | 2022 |
| Organise-D Ltd | Other services | 2020 |
| Organised by Lucy & Sara Ltd | Other services | 2026 |
| Oriental Dynamics Limited | Real estate | 2022 |
| Origin Events Limited | Professional & scientific | 2004 |
| Origin Health Limited | Professional & scientific | 2005 |
| Original Big Games Ltd | Information & communication | 2024 |
| Oriri Bookings Ltd | Hospitality | 2023 |
| Oriri House Ltd | Hospitality | 2021 |
| Ormerod & Edwards Limited | Professional & scientific | 2012 |
| Orsaya Ltd | Professional & scientific | 2025 |
| Ortensio Limited | Other services | 2001 |
| Orumsoft Ltd | Information & communication | 2017 |
| Oryx Business Process Solutions Ltd | Professional & scientific | 2007 |
| Osamudiame Ltd | Arts & recreation | 2024 |
| Osbi Limited | Information & communication | 2011 |
| Oscar Nilsson TAB Ltd | Wholesale & retail | 2025 |
| Osiris Capital Investments Limited | Financial services | 2026 |
| Osmil Limited | Professional & scientific | 2020 |
| Ossie Building Solutions Limited | Construction | 2024 |
| OTK Properties Ltd | Real estate | 2017 |
| OTK Property Solutions Ltd | Real estate | 2017 |
| Otolini Limited | Manufacturing | 2025 |
| Otrebor Limited | Information & communication | 2025 |
| Ourhome Residents Association Limited | Administrative & support | 1986 |
| OUT and Aligned CIC | Education | 2026 |
| Outlet Centres International (UK) Limited | Professional & scientific | 1997 |
| Outlook Therapeutics Ltd | Professional & scientific | 2012 |
| Outsidelife Limited | Professional & scientific | 2019 |
| Outtrip International Ltd | Information & communication | 2021 |
| Oval Estates Limited | Construction | 2019 |
| Ovenclean (Farnham) Limited | Administrative & support | 2008 |
| Overdrive Digital Limited | Professional & scientific | 2016 |
| Overdrive Ecommerce Ltd | Wholesale & retail | 2022 |
| Overdrive Games Ltd | Information & communication | 2026 |
| OVERTREE13 Limited | Administrative & support | 2024 |
| Owen Isherwood (Dorking) Ltd | Professional & scientific | 2026 |
| Owen Isherwood (Horsham) Ltd | Professional & scientific | 2026 |
| Owen Isherwood Holdings Limited | Financial services | 2023 |
| Owen Isherwood Limited | Professional & scientific | 2017 |
| Owen Isherwood Property Management Limited | Households | 2023 |
| Owen Shipp Commercial Limited | Professional & scientific | 2014 |
| Owens Business Solutions Limited | Professional & scientific | 2010 |
| Owen’S Gourmet Ltd | Hospitality | 2020 |
| Owners Trading Limited | Administrative & support | 2023 |
| Oxford Advanced Living Limited | Construction | 2015 |
| Oxford Investment Advisors Ltd | Professional & scientific | 2020 |
| Oxford Medpharma Ltd | Wholesale & retail | 2016 |
| Oyoa Ltd | Professional & scientific | 2022 |
| Oyster HR Ltd | Professional & scientific | 2020 |
| Oyster Lane Management Services Limited | Professional & scientific | 1975 |
| OZ Capital & Property Limited | Hospitality | 2015 |
| O’Hare&Co Limited | Financial services | 2024 |
| P & P Building Services Ltd | Construction | 2017 |
| P J Associates Limited | Professional & scientific | 1995 |
| P J Ford Electrical Services Limited | Construction | 2018 |
| P J Whitmarsh Limited | Construction | 2003 |
| P Pestle & Sons Ltd | Construction | 2016 |
| P Squared Photography Ltd | Professional & scientific | 2024 |
| P.B.O. Limited | Transport & logistics | 1995 |
| P.J. HI FI Limited | Wholesale & retail | 2001 |
| P2 Food Ltd | Hospitality | 2026 |
| P2 Worplesdon Limited | Construction | 2026 |
| P4 Coaching Ltd | Education | 2024 |
| P4MEDIA Limited | Arts & recreation | 2007 |
| P4RKER Media Ltd | Manufacturing | 2024 |
| PA Contractors Limited | Construction | 2014 |
| PAB Limited | Real estate | 1988 |
| Pacific Blue Solutions Limited | Education | 2002 |
| Pacioli Financial Consulting Limited | Professional & scientific | 2022 |
| Paddock Wood Residents Management Company Limited | Professional & scientific | 2020 |
| Padel FLO Ltd | Arts & recreation | 2025 |
| Padel United Limited | Arts & recreation | 2024 |
| Padelone Ltd | Wholesale & retail | 2022 |
| PAE Business Limited | Information & communication | 2000 |
| Pagasa Ltd | Professional & scientific | 2022 |
| Pagoda Media Ltd | Information & communication | 2013 |
| Paintbox Project Ltd | Arts & recreation | 2016 |
| Palaiopoli Estates Limited | Real estate | 2025 |
| Palmers Tree Specialists Limited | Administrative & support | 2021 |
| Palmwidget Internet Corporation Limited | Extraterritorial | 1999 |
| Palomar Properties Limited | Real estate | 1993 |
| Pamir Pizza Shop Limited | Hospitality | 2019 |
| Pancreatic Cancer Action | Health & social care | 2010 |
| Panecea Group Limited | Information & communication | 2021 |
| Panodyssey Limited | Professional & scientific | 2008 |
| Panosun Ltd | Wholesale & retail | 1993 |
| Pantech Auto Technicians Limited | Wholesale & retail | 1996 |
| Panvista Productions Limited | Information & communication | 2009 |
| Paper Moon Bookshop Ltd | Wholesale & retail | 2025 |
| Paradigm Design Products Limited | Professional & scientific | 2006 |
| Paradise Decorating & Home Improvements Ltd | Construction | 2023 |
| Paradisiio Limited | Professional & scientific | 2017 |
| Paradox Entertainments Group Ltd | Financial services | 2026 |
| Paradox Parlours Ltd | Arts & recreation | 2016 |