| OD Mortgages Ltd | Financial services | 2020 |
| OD Properties Ltd | Real estate | 2022 |
| Odaksan Ltd | Wholesale & retail | 2022 |
| ODD Fancy Kitchen Limited | Hospitality | 2024 |
| Odedara Property Investment Ltd | Real estate | 2026 |
| Odedra Group of Company Ltd | Wholesale & retail | 2022 |
| Odedra Logistics Ltd | Transport & logistics | 2025 |
| Odedra Transport Ltd | Transport & logistics | 2026 |
| Oden Constulting Ltd | Administrative & support | 2018 |
| Odeon Motors Limited | Administrative & support | 2009 |
| Odion @Large Ltd | Administrative & support | 2023 |
| ODM (Holdings) UK Limited | Financial services | 2018 |
| ODM Electronics Ltd | Wholesale & retail | 2025 |
| Odonesa Property Holdings Ltd | Real estate | 2025 |
| Odongo Properties Ltd | Real estate | 2025 |
| Odra Mini Ltd | Wholesale & retail | 2024 |
| Odstone Agellus Limited | Professional & scientific | 2004 |
| ODW Productions Ltd | Arts & recreation | 2022 |
| ODW Property Ltd | Real estate | 2023 |
| Odysseas Ltd | Financial services | 2018 |
| Odyssey (Leicester) Limited | Administrative & support | 2015 |
| Odyssey Counselling Limited | Professional & scientific | 2021 |
| OE22 Ltd | Other services | 2021 |
| Oehler-Bauunternehmungen Limited | Professional & scientific | 2000 |
| OEM - Automatic Limited | Wholesale & retail | 1988 |
| OEM Electronics Limited | Wholesale & retail | 2001 |
| OEM Property Limited | Real estate | 1993 |
| Oemplusdirect Ltd | Wholesale & retail | 2025 |
| Oertli Tooling UK Limited | Wholesale & retail | 2004 |
| Oeuf HOF Limited | Agriculture & fishing | 1975 |
| Ofad International Support Services Limited | Administrative & support | 2021 |
| Ofajet Limited | Professional & scientific | 2026 |
| OFF Grind Limited | Wholesale & retail | 2024 |
| OFF the Pegg Homes Ltd | Real estate | 2020 |
| Offer UK Limited | Health & social care | 2025 |
| OFFER4UNI Ltd | Wholesale & retail | 2012 |
| Offera Studio Ltd | Information & communication | 2026 |
| Office & Furniture Solutions Ltd | Transport & logistics | 2019 |
| Office Arena Limited | Real estate | 2013 |
| Office of Modern Governance Ltd | Professional & scientific | 2017 |
| Office Printing Solutions Limited | Wholesale & retail | 2007 |
| Office Studios UK Ltd | Real estate | 2025 |
| Office Supplies Broker Ltd | Other services | 2020 |
| Office Update Limited | Wholesale & retail | 2001 |
| Officetwelve Limited | Manufacturing | 2007 |
| Official Luntrix Ltd | Wholesale & retail | 2025 |
| Official Network Ltd | Other services | 2015 |
| Offiplace Ltd | Other services | 2025 |
| Offshore Apparel Ltd | Manufacturing | 2026 |
| Offshore Weather Services (UK) Limited | Extraterritorial | 2005 |
| Offshore Wind Team Limited | Professional & scientific | 2024 |
| Oflur Holdings Limited | Financial services | 2002 |
| Oflur Property Limited | Extraterritorial | 2002 |
| Ofma Ltd | Wholesale & retail | 2021 |
| Ofor Pharma Ltd | Wholesale & retail | 2022 |
| OFP Marketing Ltd | Professional & scientific | 2025 |
| OFT Group Limited | Hospitality | 2025 |
| OG Energy Services Limited | Wholesale & retail | 2019 |
| OG Kettles Ltd | Wholesale & retail | 2026 |
| OG Mangoes Ltd | Wholesale & retail | 2023 |
| Ogbugbushere Ltd | Health & social care | 2024 |
| Oggi Limited | Hospitality | 2016 |
| Oguk Limited | Wholesale & retail | 2005 |
| OH My Bites Ltd | Manufacturing | 2026 |
| OH My COD (Sandhills) Ltd | Hospitality | 2016 |
| OH My Golf Limited | Arts & recreation | 2015 |
| OH My Mango Ltd | Wholesale & retail | 2024 |
| OH My Vegan Ltd | Manufacturing | 2024 |
| OH SO Pretty Beauty Limited | Other services | 2019 |
| Ohana Business Consultancy Limited | Professional & scientific | 2015 |
| Ohana Promotions Ltd | Professional & scientific | 2025 |
| Oheb London Limited | Wholesale & retail | 2025 |
| OHK Holdings Limited | Administrative & support | 2019 |
| Ohno.Fashion Ltd | Manufacturing | 2023 |
| OIL Heating Solutions Limited | Construction | 2018 |
| OIM Group Ltd | Manufacturing | 2024 |
| Oishee Ltd | Health & social care | 2016 |
| OJ Tech Ltd | Manufacturing | 2021 |
| Ojas Nutrition Ltd | Health & social care | 2026 |
| OJC Fencing and Construction Ltd | Construction | 2026 |
| Ojddl Estate Agents Ltd | Real estate | 2018 |
| OJK Enterprises Ltd | Wholesale & retail | 2026 |
| Ojsconstruction Ltd | Construction | 2021 |
| OJW Engineering Solutions Ltd | Professional & scientific | 2025 |
| OK Caribbean Cuisine Ltd | Hospitality | 2024 |
| OK Hand Car Wash Ltd | Other services | 2024 |
| OK Property Leic Ltd | Real estate | 2021 |
| Okaro Ltd | Health & social care | 2024 |
| Okavango Deep Cleaning SER Ltd | Administrative & support | 2026 |
| Okeover Eminent Ltd | Administrative & support | 2015 |
| Okeover Properties Limited | Financial services | 2015 |
| Okhai Kinship Ltd | Public administration | 2026 |
| Okno Ltd | Real estate | 2018 |
| Okphotography Limited | Professional & scientific | 2014 |
| Oktawia Ltd | Transport & logistics | 2011 |
| Oktopay UK Limited | Information & communication | 2020 |
| Okuh Group Limited | Professional & scientific | 2016 |
| OLA Groups Ltd | Health & social care | 2023 |
| Olann Limited | Administrative & support | 2025 |
| Olatade Care Limited | Health & social care | 2016 |