| OAS Solutions Limited | Construction | 2003 |
| Oasis Bidco 1 Limited | Financial services | 2023 |
| Oasis Midco 1 Limited | Financial services | 2023 |
| Oasis Properties UK Limited | Real estate | 2003 |
| Oasis Topco 1 Limited | Financial services | 2023 |
| OAT Projects Limited | Construction | 2025 |
| OAT Ventures Ltd | Real estate | 2024 |
| OB Solutions Limited | Professional & scientific | 2004 |
| Obaróxa Ltd | Wholesale & retail | 2026 |
| OBD Motors Ltd | Wholesale & retail | 2025 |
| OBD Property Investments Ltd | Real estate | 2024 |
| OBD X Box Ltd | Wholesale & retail | 2018 |
| Obeng Tech Ltd | Information & communication | 2025 |
| Obertelli Group Limited | Financial services | 2016 |
| Obertelli Transport Limited | Transport & logistics | 2009 |
| Obex Building Services Limited | Construction | 2011 |
| OBH Food and Packing Ltd | Wholesale & retail | 2025 |
| OBIKAY1 Ltd. | Manufacturing | 2018 |
| OBJ Properties Limited | Real estate | 2025 |
| Objective Clarity Ltd | Professional & scientific | 2008 |
| Objet D'Art Salon Limited | Other services | 2004 |
| Obligeitsolutions Limited | Information & communication | 2013 |
| Oblivion Gaming Ltd | Information & communication | 2021 |
| OBS Barcelona Ltd | Professional & scientific | 2016 |
| OBS Management Limited | Extraterritorial | 2005 |
| OBS Recovery Ltd | Professional & scientific | 2017 |
| Observance Journals Ltd | Wholesale & retail | 2024 |
| Obsidian and Basalt Ltd | Information & communication | 2018 |
| Obsidian House Ltd | Real estate | 2023 |
| Obsidian HR Ltd | Administrative & support | 2024 |
| Obsidise Ltd | Wholesale & retail | 2026 |
| Obyella Collections Ltd | Administrative & support | 2026 |
| Ocals Ltd | Professional & scientific | 2008 |
| Ocapi Limited | Information & communication | 2019 |
| Occasion Cakes Limited | Wholesale & retail | 2025 |
| Occleston Biopharma Limited | Professional & scientific | 2022 |
| Ocean Aesthetics Ltd | Other services | 2024 |
| Ocean Group Estates Ltd | Real estate | 2026 |
| Ocean Group Transport Ltd | Transport & logistics | 2021 |
| Ocean Medical Services Ltd | Health & social care | 2024 |
| Ocean Premier Limited | Hospitality | 2018 |
| Ocean Travels Ltd | Transport & logistics | 2017 |
| OCEAN360 Limited | Wholesale & retail | 2021 |
| Oceanevo Limited | Wholesale & retail | 2020 |
| Ocrj Ltd | Construction | 2025 |
| Octagon Catering Services Limited | Hospitality | 1987 |
| Octagon Theatre Productions Ltd | Arts & recreation | 2014 |
| Octagon Theatre Trust Limited | Arts & recreation | 1966 |
| Octagon Work Wear Ltd | Wholesale & retail | 2024 |
| Octasoft Ltd | Information & communication | 2008 |
| Octobud Limited | Information & communication | 2018 |
| Octobud Ventures Limited | Real estate | 2024 |
| Octopus Construction Management Ltd | Construction | 2022 |
| Oculus Properties Ltd | Real estate | 2025 |
| Od-Bace Ltd | Real estate | 2016 |
| ODD Muse Retail UK Limited | Wholesale & retail | 2025 |
| Oddity Alley Ltd | Wholesale & retail | 2025 |
| Oddly Digital Ltd | Information & communication | 2023 |
| Oden Finance and Marketing Solutions Ltd | Administrative & support | 2026 |
| Odette Care Services Ltd | Construction | 2017 |
| Odin Ayre Ltd | Transport & logistics | 2024 |
| Odium Ltd | Hospitality | 2026 |
| Odorem Limited | Wholesale & retail | 2024 |
| ODYSSEY9 Academy CIC | Arts & recreation | 2021 |
| OEH Paraplanning Ltd | Administrative & support | 2024 |
| Oeilcare Ltd | Health & social care | 2023 |
| OEL Holdings Ltd | Real estate | 2026 |
| Oena Ltd | Other services | 2022 |
| Oepc Ltd. | Other services | 2019 |
| OFF Plan Management Ltd | Real estate | 2021 |
| Off-Tech (UK) Limited | Water & waste | 2003 |
| Offate Ltd | Transport & logistics | 2026 |
| Offers Direct Ltd | Wholesale & retail | 2025 |
| OFFIC3 Limited | Real estate | 2024 |
| Office Design Ltd | Manufacturing | 2019 |
| Officiency Consult Limited | Administrative & support | 2021 |
| Offline Digital Limited | Information & communication | 2011 |
| OFG (UAE Holdings) Limited | Financial services | 2026 |
| Ofield's Skip Hire Ltd | Water & waste | 2020 |
| OFS (DS) Acquisitions Limited | Financial services | 2007 |
| OFS (DS) EBT Trustees Limited | Extraterritorial | 2000 |
| OFS (DS) Finance Limited | Financial services | 2007 |
| OFS (DS) Holdings Limited | Financial services | 2007 |
| OGB4PAU Ltd | Health & social care | 2026 |
| Oghussain Ltd | Health & social care | 2017 |
| Ogifa Ltd | Wholesale & retail | 2026 |
| Ogife Investments Ltd | Real estate | 2020 |
| OH Heck Limited | Wholesale & retail | 2021 |
| OH My Goodness Ltd | Hospitality | 2025 |
| OH Twaddi Ltd | Wholesale & retail | 2025 |
| Ohclo Consultancy Ltd | Other services | 2024 |
| Ohmea Investments Ltd | Real estate | 2016 |
| Ohonesix Digital Ltd | Information & communication | 2022 |
| Ohshoot Ltd | Other services | 2022 |
| Oikos Family Holdings Limited | Real estate | 2021 |
| Oiors Limited | Wholesale & retail | 2025 |
| Ojdetails Limited | Administrative & support | 2025 |
| Ojie Investment Limited | Transport & logistics | 2023 |
| OJS Investments Limited | Administrative & support | 2024 |
| Ojugo Limited | Transport & logistics | 2012 |