| Olive Kitchens Ltd | Wholesale & retail | 2019 |
| Olive Legal Associates Ltd | Professional & scientific | 2023 |
| Olive More Ventures Limited | Construction | 2012 |
| Olive Property Limited | Construction | 2014 |
| Oliveglade Ltd | Hospitality | 2014 |
| Oliver Woollard Developments Ltd | Real estate | 2024 |
| Olivia Cafe Ltd | Hospitality | 2025 |
| Oliviolette Limited | Real estate | 2024 |
| Oltrax Limited | Administrative & support | 2008 |
| Olympia Consultancy Limited | Professional & scientific | 2022 |
| Olympia Park Ltd | Real estate | 2025 |
| Olympus Skyline Ltd | Real estate | 2025 |
| OM Signalling Ltd | Other services | 2022 |
| Omagek Limited | Wholesale & retail | 2016 |
| Omans Furniture Ltd | Manufacturing | 2020 |
| Omar Aftab Ltd | Health & social care | 2017 |
| Omar Hassan Ltd | Real estate | 2019 |
| Omar's Balti House Ltd | Hospitality | 2023 |
| Omark Ltd | Professional & scientific | 2017 |
| Omatel Limited | Manufacturing | 2024 |
| Omega Analytic Systems Limited | Administrative & support | 2016 |
| Omega Consultancy Ltd | Administrative & support | 2026 |
| Omega Consulting Engineers Ltd | Professional & scientific | 2020 |
| Omega Roofing Contractors Limited | Construction | 2026 |
| Omega Security Systems Limited | Construction | 2006 |
| Omega Steel Limited | Wholesale & retail | 1995 |
| Omega Traders Limited | Wholesale & retail | 2018 |
| Omegarender LLP | | 2016 |
| Omicron Quantity Surveying Services Limited | Professional & scientific | 2024 |
| Omid Staffing Solutions Ltd | Hospitality | 2025 |
| Omil Ltd | Transport & logistics | 2024 |
| Omni Design & Developments Limited | Professional & scientific | 2026 |
| Omni Design and Construction Ltd | Construction | 2026 |
| Omnia Supplies Ltd | Wholesale & retail | 2018 |
| Omnitek Group Ltd | Construction | 2025 |
| OMS Civils Ltd | Construction | 2026 |
| OMS Lubritek Limited | Professional & scientific | 2016 |
| ON Demand Printing Ltd | Manufacturing | 2023 |
| ON PAR Parfum Ltd | Wholesale & retail | 2021 |
| ON Point Barbers Limited | Other services | 2019 |
| ON Q Snooker Lounge Ltd | Other services | 2022 |
| ON Th'Edge Productions Limited | Arts & recreation | 2025 |
| ON the Move Couriers Ltd | Transport & logistics | 2025 |
| ON the Rhodes Limited | Hospitality | 2024 |
| ON Time Home Improvements Ltd | Construction | 2017 |
| ON Time Repairs Ltd | Wholesale & retail | 2018 |
| ON Trend Kitchens MTK Ltd | Construction | 2025 |
| On-Demand Delivery Service Ltd | Transport & logistics | 2023 |
| On-Site Everything Ltd | Wholesale & retail | 2024 |
| On-Time Human Resources UK Ltd | Administrative & support | 2025 |
| Onalim IT Limited | Information & communication | 2022 |
| Oncisive Limited | Professional & scientific | 2019 |
| Ondemand Landscaping and Powerwashing Ltd | Administrative & support | 2025 |
| Ondiam Ltd | Wholesale & retail | 2020 |
| Ondigi Solutions Ltd | Information & communication | 2026 |
| One Bill Solution (OBS) Ltd | Administrative & support | 2014 |
| One Call Does IT ALL Contractors Limited | Manufacturing | 2025 |
| One Eleven Props Ltd | Information & communication | 2023 |
| One in a Million (Enterprises) Limited | Arts & recreation | 2010 |
| One in a Million (Sports) | Arts & recreation | 2007 |
| One in a Million Free School | Education | 2012 |
| One Investment and Subsidiary Companies Limited | Administrative & support | 2020 |
| One Leeds Road Bradford Limited | Real estate | 2022 |
| One Leeds Road Management Ltd | Real estate | 2024 |
| One Lighthouse View Ltd | Wholesale & retail | 2019 |
| One Path Events Ltd | Professional & scientific | 2026 |
| One Precision Ltd | Other services | 2021 |
| One Shot Leisure Centre Ltd | Arts & recreation | 2017 |
| One Stop Banqueting Solutions Limited | Hospitality | 2021 |
| One Stop Building Services Ltd | Construction | 2019 |
| One Stop Business Solutions Yorks Limited | Wholesale & retail | 2024 |
| One Stop Car Clinic Ltd | Wholesale & retail | 2015 |
| One Stop Deals Limited | Wholesale & retail | 2019 |
| One Stop Fruit & VEG Limited | Wholesale & retail | 2017 |
| One Stop Management Limited | Real estate | 2025 |
| One Stop Marquee Limited | Hospitality | 2021 |
| One Stop Properties Yorkshire Ltd | Real estate | 2022 |
| One Stop Renovations Ltd | Construction | 2019 |
| One Stop Tooling Limited | Manufacturing | 2011 |
| One Stop Wonder Ltd | Health & social care | 2015 |
| One TEN Aura Ltd | Wholesale & retail | 2026 |
| One TEN Physio Rehab Ltd | Health & social care | 2026 |
| One Tree Interior Projects Ltd | Construction | 2026 |
| One Way to Paradise Ltd | Information & communication | 2021 |
| One World (GB) Limited | Wholesale & retail | 2009 |
| One World Couriers ALL Over Ltd | Transport & logistics | 2018 |
| One Wrap Packaging Ltd | Professional & scientific | 2024 |
| One-Click Pick Ltd | Wholesale & retail | 2023 |
| ONE10 Contractors Limited | Construction | 2023 |
| ONE10 Investments Ltd | Real estate | 2023 |
| Oneclic Limited | Wholesale & retail | 2020 |
| Onekey Investments Ltd | Real estate | 2020 |
| Onestop Solutions Ltd | Wholesale & retail | 2025 |
| Oniraa Limited | Wholesale & retail | 2025 |
| Online Cleanse Limited | Administrative & support | 2019 |
| Online Design & Digital Marketing Ltd | Administrative & support | 2013 |
| Online Discount Mart Ltd | Wholesale & retail | 2022 |
| Online Haven Direct Limited | Wholesale & retail | 2025 |
| Online Readers Ltd | Wholesale & retail | 2020 |
| Online Shopping Engine Ltd | Professional & scientific | 2010 |