| One Life Estate Ltd | Real estate | 2020 |
| One Life Estate Management Ltd | Real estate | 2019 |
| One Life Grow More Ltd | Real estate | 2022 |
| One Life Property Ltd | Real estate | 2019 |
| One Life Real Estate Ltd | Real estate | 2020 |
| One Life Reality Ltd | Real estate | 2017 |
| One Life Trading Limited | Wholesale & retail | 2026 |
| One Night Drinks Ltd | Manufacturing | 2026 |
| One OFF Solution Ltd | Households | 2023 |
| One Waste Clearance Ltd | Water & waste | 2014 |
| ONE10 Transfers Limited | Transport & logistics | 2022 |
| Onegin Mechanical Services Limited | Construction | 2014 |
| Oniri Couriers Ltd | Transport & logistics | 2022 |
| Online Skills Training Ltd | Education | 2019 |
| Onlinehome Limited | Wholesale & retail | 2025 |
| Only Shop Ltd | Wholesale & retail | 2025 |
| Ontech Strategic Solutions Limited | Information & communication | 2026 |
| OOF Construction Limited | Construction | 2016 |
| Open ARM Residential Care Services Ltd | Health & social care | 2025 |
| Open Date Equipment Limited | Manufacturing | 1974 |
| Open Road Enterprise Limited | Wholesale & retail | 2025 |
| Opkfam Limited | Wholesale & retail | 2009 |
| Optic Link UK Ltd | Information & communication | 2025 |
| Opticlean Ltd | Administrative & support | 2025 |
| OR Logistics Limited | Transport & logistics | 2026 |
| Orabuild Ltd | Construction | 2015 |
| Orbex.London Ltd | Wholesale & retail | 2025 |
| Orbit Software Ltd | Information & communication | 2019 |
| Organic Cleaning Ltd | Administrative & support | 2025 |
| Organic Seeds Trade Consult Ltd | Professional & scientific | 2024 |
| Organised Good Vibes and Ventures CIC | Arts & recreation | 2025 |
| Origin Mineral Group Ltd | Mining & quarrying | 2026 |
| Orion Pest Control Services Ltd | Administrative & support | 2019 |
| Orlyk Construction Ltd | Construction | 2024 |
| Ortentik Ltd | Construction | 2023 |
| Orvella Homes Ltd | Real estate | 2026 |
| OS Drylining Ltd | Construction | 2025 |
| OSA Accountancy Ltd | Professional & scientific | 2014 |
| OSA Bookkeeping Ltd | Professional & scientific | 2025 |
| Oscos Removal Ltd | Transport & logistics | 2025 |
| Oseita Ltd | Health & social care | 2013 |
| Osman Squad Preschool Limited | Education | 2023 |
| Otif Ltd | Construction | 2026 |
| OUR Eden Homes Limited | Real estate | 2025 |
| Outreachko Limited | Wholesale & retail | 2021 |
| Outreachxpert Ltd | Information & communication | 2018 |
| Overclockin Ltd | Professional & scientific | 2022 |
| OVI Floor Solutions Limited | Construction | 2016 |
| Ovington Consultancy Solutions Ltd | Professional & scientific | 2018 |
| OW Partners Ltd | Hospitality | 2025 |
| Owino Trading Company Ltd | Wholesale & retail | 2018 |
| Own Designs Ltd | Professional & scientific | 2023 |
| Own Global Estates Ltd | Real estate | 2024 |
| Owusu E & Sons Limited | Health & social care | 2011 |
| Oxford Cartographers Limited | Administrative & support | 1998 |
| OZ Cars London Ltd | Wholesale & retail | 2021 |
| OZ CR4 Properties Ltd | Real estate | 2026 |
| Ozbuild Limited | Construction | 2019 |
| OZC Construction & Management Services Ltd | Construction | 2021 |
| Ozom UK Ltd | Health & social care | 2022 |
| P J Furnitures Limited | Construction | 2015 |
| P Sullivan & Sons Limited | Financial services | 2011 |
| P&K FIX Ltd | Construction | 2015 |
| P&M Grabovschi Ltd | Manufacturing | 2025 |
| P&S Construction Ltd | Construction | 2022 |
| P&S Refurb Ltd | Manufacturing | 2024 |
| P2R Builders Ltd | Construction | 2018 |
| Pabenas Care Ltd | Real estate | 2015 |
| Pace Trader Ltd | Wholesale & retail | 2023 |
| Pachedu Club Ltd | Health & social care | 2023 |
| Pagimartins Investments Ltd | Real estate | 2024 |
| Paint Shack ( Surrey ) Ltd | Construction | 2016 |
| Paint Shack Online Ltd | Wholesale & retail | 2020 |
| Paksis International Limited | Information & communication | 2005 |
| PAL Construction London Limited | Construction | 2018 |
| Palm Tree Trading Ltd | Wholesale & retail | 2024 |
| Pandan Co Ltd | Professional & scientific | 2026 |
| Panjad Ltd | Health & social care | 2022 |
| Papa Official Ltd | Wholesale & retail | 2026 |
| Pappyd Ltd | Administrative & support | 2021 |
| Papsolo Limited | Health & social care | 2019 |
| Paragas Pictures Ltd | Information & communication | 2023 |
| Paragon Technology Advisory Limited | Information & communication | 2024 |
| Paragon Technology Consulting Services Ltd | Information & communication | 2025 |
| Parinika Holdings Limited | Professional & scientific | 2024 |
| Park Lodge Residents Company Limited | Real estate | 1988 |
| Parsons Property Solutions Limited | Real estate | 2026 |
| Parthenope Exercise Coaching and Sports Performance Ltd | Other services | 2023 |
| PARTS4HYBRID Ltd | Wholesale & retail | 2021 |
| Pasco Buildings Services Limited | Construction | 2021 |
| Passportsxplease Limited | Administrative & support | 2023 |
| Pasta Roma Ltd | Hospitality | 2020 |
| PAT & KEL Limited | Real estate | 2020 |
| Patch Engineering Designs Ltd | Professional & scientific | 2009 |
| Patel & Co UK Ltd | Wholesale & retail | 2025 |
| Path Radio Ltd | Other services | 2023 |
| Pathway School Enfield Ltd | Education | 2025 |
| Patney HCW Ltd | Wholesale & retail | 2016 |
| Pato Construction Ltd | Construction | 2018 |
| Patrick and Sons Ltd | Wholesale & retail | 2023 |