| Oakley Builders Leeds Limited | Construction | 2025 |
| Oakley Finance Ltd | Financial services | 2024 |
| Oaklodge Limited | Real estate | 2012 |
| Oakon Estates Ltd | Real estate | 2026 |
| Oakridge 31 Property Limited | Real estate | 2025 |
| Oakridge Ranch Limited | Real estate | 2026 |
| Oakstone Enterprises Ltd | Wholesale & retail | 2026 |
| Oakstone Plumbing Company Ltd | Construction | 2022 |
| Oaktree Finance Ltd | Financial services | 2019 |
| Oaktree Haven Ltd | Health & social care | 2024 |
| Oaktree Property Solutions Limited | Real estate | 2025 |
| Oakview Homes Group Limited | Real estate | 2024 |
| Oakview Portfolio Limited | Real estate | 2025 |
| Oakwell (Leeds) Ltd | Real estate | 2013 |
| Oakwell Capital Management | Financial services | 2021 |
| Oakwell Projects (Leeds) Limited | Real estate | 1991 |
| Oakwell Projects 2000 Limited | Real estate | 2022 |
| Oakwell Projects Limited | Real estate | 2010 |
| Oakwell Roofing Ltd | Construction | 2022 |
| Oakwell Securities Limited | Real estate | 1988 |
| Oakwood Business Finance Limited | Financial services | 2020 |
| Oakwood Fisheries Limited | Hospitality | 2025 |
| Oakwood Foods Limited | Hospitality | 2024 |
| Oakwood Fort Limited | Construction | 2023 |
| Oakwood Land Surveys Ltd | Professional & scientific | 2024 |
| Oakwood Lane Barber Shop Ltd | Other services | 2022 |
| Oakwood Lane Management Company Limited | Real estate | 2006 |
| Oakwood Legacy Planning Ltd | Financial services | 2025 |
| Oakwood Manor Limited | Hospitality | 2018 |
| Oakwood Manor Property Limited | Real estate | 2018 |
| Oakwood Nominees Limited | Financial services | 1976 |
| Oakwood OH Consultancy Ltd. | Health & social care | 2016 |
| Oakwood Property Group Yorkshire Ltd | Real estate | 2024 |
| Oakwood Smiles Ltd | Health & social care | 2020 |
| Oakwood Solicitors Limited | Professional & scientific | 2009 |
| Oakwood Traders and Residents Association | Professional & scientific | 2012 |
| Oakwood Traders Ltd | Administrative & support | 2025 |
| Oakwood Travel Limited | Administrative & support | 1984 |
| OAL Travels Ltd | Administrative & support | 2019 |
| OAM Associates Ltd | Administrative & support | 2019 |
| Oana Logistic Ltd | Transport & logistics | 2020 |
| Oankaar Ltd | Information & communication | 2017 |
| OAO (Leeds) Ltd | Hospitality | 2023 |
| Oasis Bar and Restaurant Limited | Hospitality | 2026 |
| Oasis Car Solutions Limited | Wholesale & retail | 2014 |
| Oasisé Properties Ltd | Real estate | 2025 |
| OAT & Co. Properties Ltd | Real estate | 2017 |
| Oatcake Property Limited | Real estate | 2020 |
| Oatland News Limited | Transport & logistics | 2017 |
| Oatlands Mount Properties Limited | Real estate | 2001 |
| Oatlands Tyre & Motor Company Harrogate Limited | Professional & scientific | 2013 |
| Oatlands Tyre & Motor Company Limited | Wholesale & retail | 1982 |
| Oaza European Foods Ltd | Wholesale & retail | 2018 |
| OB Special Ltd | Health & social care | 2022 |
| Obakrown Limited | Health & social care | 2026 |
| Oban Propco Limited | Real estate | 2024 |
| Obantec Ltd | Professional & scientific | 2021 |
| OBE Property Management Limited | Real estate | 2016 |
| Obelisk 16 Limited | Other services | 2016 |
| Oberon Auctions Ltd | Administrative & support | 2024 |
| Oberon Property Ltd | Real estate | 2018 |
| Oberon Solar & Heating Ltd | Construction | 2022 |
| OBF Cleaning Services Ltd | Administrative & support | 2025 |
| OBI Haven Care Limited | Health & social care | 2026 |
| OBI Trading UK Ltd | Wholesale & retail | 2023 |
| Obiluc Limited | Administrative & support | 2021 |
| Obimanso Ltd | Information & communication | 2024 |
| Obinne Limited | Health & social care | 2024 |
| Obioro Healthcare Services Ltd | Health & social care | 2023 |
| Obleas to Go Ltd | Hospitality | 2025 |
| Oblin Energy Ltd | Energy | 2011 |
| Oblin Holdings Limited | Manufacturing | 2008 |
| Oblong Ltd | Other services | 1996 |
| Obody UK Limited | Other services | 2025 |
| Oboe Group Ltd | Hospitality | 2024 |
| Obosa-Etinosa Medical Ltd | Health & social care | 2022 |
| Obridge Realty Ltd | Real estate | 2024 |
| Obryx Ltd | Information & communication | 2026 |
| Obsidyan Motors Ltd | Wholesale & retail | 2026 |
| Obverse Film Services Ltd | Information & communication | 2020 |
| OC Construction Yorkshire Ltd | Construction | 2023 |
| OC Engineering Services Limited | Financial services | 2015 |
| Ocadia Marketing Solutions Ltd | Professional & scientific | 2024 |
| Ocan Transport (UK) Ltd | Transport & logistics | 2015 |
| Ocarina Financial Systems Limited | Information & communication | 1998 |
| Occams Controller Limited | Manufacturing | 2025 |
| Occupational Therapists Without Borders Ltd | Administrative & support | 2019 |
| Occupier Property Solutions Ltd | Real estate | 2020 |
| Ocean Across Solutions Ltd | Information & communication | 2023 |
| Ocean Breeze Travel Ltd | Transport & logistics | 2024 |
| Ocean Charge Ltd | Energy | 2024 |
| Ocean Fisheries Leeds Ltd | Hospitality | 2022 |
| Ocean Procurement Ltd | Manufacturing | 2024 |
| Ocean Travel Express Ltd | Transport & logistics | 2024 |
| Ocean Trawl Grimsby Limited | Wholesale & retail | 2014 |
| Oceanez Ltd | Professional & scientific | 2021 |
| Oceans Fisheries Ltd | Hospitality | 2020 |
| Oceans Group Ltd | Information & communication | 2026 |
| Oceansaver Ltd | Wholesale & retail | 2018 |
| Ocha Ltd | Hospitality | 2022 |