| Oparo Social 1B Ltd | Construction | 2020 |
| Oparo Social 1C Limited | Real estate | 2021 |
| Oparo Social 1D Ltd | Real estate | 2021 |
| Oparo Social 1E Ltd | Real estate | 2021 |
| Oparo Social Addiscombe Ltd | Real estate | 2022 |
| Open Screen Limited | Information & communication | 2016 |
| Operance Connect Limited | Administrative & support | 2026 |
| Ophir Energy Indonesia Limited | Mining & quarrying | 2007 |
| Ophir Energy Limited | Mining & quarrying | 2004 |
| Ophir Holdings & Services (UK) Limited | Mining & quarrying | 2016 |
| Ophir Mexico Limited | Mining & quarrying | 2016 |
| Optimist Performance Ltd | Professional & scientific | 2020 |
| Opus Capital London Limited | Financial services | 2016 |
| Oratorian Estates Ltd | Real estate | 2025 |
| Orchard Close Residents (Arncott) Limited | Households | 2009 |
| Orchard Close Residents Limited | Households | 1992 |
| Orchard Dene Limited | Construction | 2021 |
| Orchard Gardens (BIX) Management Company Limited | Construction | 2015 |
| Orchard Grove (Orpington) Management Limited | Real estate | 2007 |
| Orchard Grove (Yarnton) Management Limited | Households | 2010 |
| Oriental RUG Cleaning Ltd | Administrative & support | 2021 |
| Origin 31 Ltd | Wholesale & retail | 2015 |
| Original Intent Limited | Health & social care | 2017 |
| Ornn Ltd | Professional & scientific | 2025 |
| Osborne Gate Management Company (Bracknell) Limited | Real estate | 2018 |
| Osokey Ltd. | Information & communication | 2016 |
| OT Advisory Limited | Professional & scientific | 2023 |
| OTR Development Ltd | Professional & scientific | 2017 |
| Oumono Club Limited | Administrative & support | 2024 |
| OUR Female Collective Ltd | Administrative & support | 2026 |
| Outback Holdings Limited | Arts & recreation | 1994 |
| Outback Rigging Limited | Arts & recreation | 1994 |
| Outback Services Limited | Administrative & support | 1994 |
| Outback Ventures Ltd | Arts & recreation | 2025 |
| Outout Parties Ltd | Administrative & support | 2025 |
| Over Land and Sea (Leicester) Limited | Professional & scientific | 2015 |
| Oversquare Limited | Professional & scientific | 2016 |
| Overstel Limited | Households | 1982 |
| Oxford Cycle Support Ltd | Manufacturing | 2012 |
| Oxford Gliding Company Limited | Arts & recreation | 1938 |
| Oxford House Property Management Ltd | Real estate | 2024 |
| Oxford Technology Management Limited | Administrative & support | 1972 |
| Oxon Energy Limited | Construction | 2014 |
| Oxon MEP Ltd | Administrative & support | 2019 |
| P&G Construction 2018 Ltd | Construction | 2018 |
| P1 1 YR Growth Limited | Financial services | 2018 |
| P1 1 YR Income Limited | Financial services | 2018 |
| P1 3 YR Growth Limited | Financial services | 2018 |
| P1 3 YR Income Limited | Financial services | 2018 |
| P1 5 YR Growth Limited | Financial services | 2018 |
| P1 5 YR Income Limited | Financial services | 2018 |
| P1 Asset Finance Limited | Financial services | 2020 |
| P1 Capital Developments Limited | Construction | 2022 |
| P1 Capital Group Limited | Financial services | 2021 |
| P1 Capital Investments Limited | Financial services | 2020 |
| P1 Capital Limited | Real estate | 2017 |
| P1 Capital Partners Limited | Real estate | 2018 |
| P1 Capital Riseley Holdings Limited | Financial services | 2022 |
| P1 Capital Rock Limited | Real estate | 2019 |
| P1 Capital S & R Limited | Professional & scientific | 2022 |
| P1 Capital Services Limited | Real estate | 2018 |
| P1 CP Secured August 2020 ( Growth ) Limited | Financial services | 2019 |
| P1 CP Secured August 2020 ( Inc ) Limited | Financial services | 2019 |
| P1 Investments Limited | Financial services | 2019 |
| P1 Ipgl Limited | Financial services | 2024 |
| P1 Millennium Limited | Financial services | 2020 |
| P1 Stewart Limited | Financial services | 2025 |
| P1 Worsfold Limited | Financial services | 2020 |
| P1COR Secured March 2024 (Growth) Ltd | Financial services | 2019 |
| P1COR Secured March 2024 (Inc) Ltd | Financial services | 2019 |
| PA Westcott Holdings Limited | Financial services | 2018 |
| Pace Equity Limited | Financial services | 1996 |
| Paddock Green (Sonning Common) M.C. Limited | Households | 2020 |
| Padel and Play Henley Limited | Arts & recreation | 2025 |
| Pain Free Plumbing Ltd | Construction | 2015 |
| Palakapya Limited | Arts & recreation | 2002 |
| Palerose Ltd | Real estate | 2023 |
| Palmera Holdings Limited | Financial services | 2014 |
| Pandaroo Limited | Real estate | 2015 |
| Papillon Events UK Limited | Professional & scientific | 2003 |
| Paragon Financial Planning Ltd | Financial services | 2003 |
| Parallel Henley Holdings Ltd | Financial services | 2026 |
| Parallel Henley Ltd | Arts & recreation | 2026 |
| Parallel Henley Propco Ltd | Real estate | 2026 |
| Parents' Centre Activities (Newham) Limited | Wholesale & retail | 1978 |
| Park House (Loudwater) Management Company Limited | Households | 2015 |
| Parkswood Ltd | Wholesale & retail | 2019 |
| Party Planners Limited | Hospitality | 2017 |
| Pasteurisers UK Ltd | Manufacturing | 2020 |
| Patisserie Franco-Belge Limited | Manufacturing | 1980 |
| Patrick Gerald Limited | Professional & scientific | 2021 |
| Paul and ME Production Ltd | Arts & recreation | 2018 |
| Paul Lovegrove Ltd | Construction | 2013 |
| Paul Marshall (Sales) Limited | | 1980 |
| Paul Scade Writing Services Ltd | Information & communication | 2023 |
| Paymi Limited | Information & communication | 2023 |
| Paywaze Limited | Professional & scientific | 2025 |
| PCO Consulting Limited | Professional & scientific | 2025 |
| Peace Advisory Services Limited | Professional & scientific | 2024 |
| Peak Recovery Limited | Health & social care | 2025 |