| OIT Management Ltd | Real estate | 2022 |
| OIT SPV Ltd | Real estate | 2023 |
| OJ Digital Automation Ltd | Professional & scientific | 2024 |
| OJB Sports Consultancy Ltd | Arts & recreation | 2021 |
| OJD Design & Build Limited | Construction | 2020 |
| OJD Services Limited | Professional & scientific | 2022 |
| OJE Waldron Ltd | Professional & scientific | 2018 |
| OJJ Group Ltd | Wholesale & retail | 2018 |
| OJR Architects Ltd | Professional & scientific | 2022 |
| OJS Underground Bunker Ltd | Hospitality | 2025 |
| OK Tyres Ltd | Wholesale & retail | 2020 |
| OK Vending Ltd | Wholesale & retail | 2023 |
| Okane J Limited | Construction | 2019 |
| OKB (NW) Limited | Real estate | 2024 |
| Okee Family Investment Company Limited | Financial services | 2026 |
| Okell Building Services Limited | Administrative & support | 2009 |
| Okestra Multibiz Ltd | Real estate | 2024 |
| Okeyo Mgmt Ltd | Real estate | 2019 |
| Okhiz Limited | Health & social care | 2017 |
| OKM International Ltd | Administrative & support | 2025 |
| OKO Health Limited | Health & social care | 2023 |
| OKQ Agency Ltd | Wholesale & retail | 2020 |
| Oktoberfest Liverpool Ltd | Hospitality | 2022 |
| Okuzi Apartments Ltd. | Real estate | 2021 |
| Okzam Limited | Wholesale & retail | 2010 |
| OLA (NW) Limited | Professional & scientific | 2019 |
| OLA Residents Ltd | Real estate | 2024 |
| Olagraevan Ltd | Other services | 2025 |
| Olajyde Limited | Health & social care | 2019 |
| Olamps Recruits UK Limited | Administrative & support | 2023 |
| Olastri Limited | Financial services | 2022 |
| Olayusnob Entrepreneurial Services Ltd. | Health & social care | 2018 |
| Old Boston Limited | Real estate | 2021 |
| Old Chapel House 1 Limited | Real estate | 2018 |
| Old Chapel House 2 Limited | Real estate | 2018 |
| Old Chapel House 3 Limited | Real estate | 2018 |
| Old Farm Core Studio Ltd | Arts & recreation | 2025 |
| Old Farm Service Station Limited | Wholesale & retail | 1982 |
| Old Hall Consultancy Ltd | Administrative & support | 2018 |
| Old Hall Street Investor Limited | Real estate | 2016 |
| Old Lerpoolian Society(The) | Arts & recreation | 1894 |
| Old Mill Lane Management Ltd | Households | 2019 |
| Old Mountain Ltd | Other services | 2014 |
| Old Roan Chippy Ltd | Hospitality | 2026 |
| Old Roan Fresh Food Ltd | Hospitality | 2024 |
| Old Roan Preschool Ltd | Education | 2019 |
| Old School Gardens Aughton Limited | Households | 2023 |
| Old Swan 1959 Limited | Extraterritorial | 2013 |
| Old Swan Express Ltd | Wholesale & retail | 2026 |
| Old Swan OFF License Ltd | Wholesale & retail | 2025 |
| Old Swan Tiles Ltd | Wholesale & retail | 2023 |
| Old Vines Limited | Hospitality | 2019 |
| Old Xaverians CIC | Arts & recreation | 2024 |
| Oldbibco VI Limited | Professional & scientific | 1930 |
| Oldbury Residential Limited | Real estate | 2014 |
| Oldbylands Limited | Hospitality | 1973 |
| Oldfield Hampers Limited | Wholesale & retail | 2020 |
| Oldgreen Limited | Wholesale & retail | 2013 |
| Oldham Bros Ltd. | Construction | 1982 |
| Oldham Brothers Recycling Ltd | Wholesale & retail | 2013 |
| Oldswan Go-Local Shop Ltd | Information & communication | 2019 |
| OLE Investments Ltd | Real estate | 2021 |
| Olebak Investments Limited | Real estate | 2026 |
| Olei Estates Ltd | Construction | 2026 |
| Oleo Consultancy Ltd | Real estate | 2022 |
| Oleo Solutions Ltd | Wholesale & retail | 2004 |
| Olevéa Aesthetics & Wellness Ltd | Other services | 2025 |
| Olican Ltd | Professional & scientific | 2025 |
| Olicana Ilkley Trading Limited | Professional & scientific | 2022 |
| Olimax Healthcare Ltd | Health & social care | 2023 |
| Olimon Marketing Limited | Wholesale & retail | 2026 |
| Olimpic Windows Limited | Construction | 2005 |
| Olive and Grape Catering Limited | Hospitality | 2019 |
| Olive Capital Limited | Professional & scientific | 2024 |
| Olive Coffee&Grill Ltd | Hospitality | 2018 |
| Olive Firth Enterprises Ltd | Information & communication | 2025 |
| Olive Franklin & Clarke Ltd | Real estate | 2023 |
| Olive Linen Limited | Other services | 2021 |
| Olive Mate Italian Kitchen Ltd | Hospitality | 2026 |
| Olive Mount Developments Ltd | Construction | 2016 |
| Olive Mount Media Limited | Arts & recreation | 2016 |
| Olive Residential Ltd | Households | 2023 |
| Olive Tree Liverpool Ltd | Hospitality | 2026 |
| Oliver's Commercial & Domestic Cleaning Ltd | Administrative & support | 2023 |
| Olivia and Louie Group Limited | Real estate | 2025 |
| Olivia Blackwell Ltd | Information & communication | 2025 |
| Olivia Buzaglo Ltd | Professional & scientific | 2024 |
| Olivia Dool Medical Ltd | Health & social care | 2026 |
| Olivia Gallagher & Sophie Washington Ltd | Other services | 2020 |
| Olivia Hairpieces Ltd | Other services | 2021 |
| Olivia Korbel Butterfly Foundation Community Interest Company | Other services | 2025 |
| Olivia Louis Ltd | Hospitality | 2025 |
| Olivia Rushton Animal Physiotherapy Ltd | Professional & scientific | 2024 |
| Olivia Sullivan Davis Ltd | Information & communication | 2024 |
| Olivica Ltd | Real estate | 2019 |
| Olivier Estates Limited | Real estate | 2018 |
| Olivsa Ltd | Real estate | 2024 |
| Olla Consultancy Ltd | Health & social care | 2015 |
| Olla Limited | Arts & recreation | 2022 |
| Ollie Optimal Health Ltd | Other services | 2025 |