| ON Rotation Ltd | Wholesale & retail | 2022 |
| ON Route Travel Limited | Administrative & support | 2017 |
| ON Sweet Limited | Real estate | 2016 |
| ON Task Plumbing & Heating Ltd | Construction | 2019 |
| ON the Line Consulting Ltd. | Professional & scientific | 2017 |
| ON the Mark (U.K.) Limited | Professional & scientific | 2003 |
| ON the Move (Location Solution) Limited | Transport & logistics | 2024 |
| ON the Spot Locksmiths Ltd | Construction | 2018 |
| ON the Verge UK CIC | Public administration | 2024 |
| ON Time Agency Ltd | Administrative & support | 2026 |
| ON Time Office Solutions Limited | Wholesale & retail | 2003 |
| ON Time Private Hire Ltd | Transport & logistics | 2022 |
| On-Task Business Supplies Ltd | Wholesale & retail | 2022 |
| ONA Digital Limited | Information & communication | 2022 |
| Onadeez Services Ltd | Professional & scientific | 2023 |
| Onaroll Street Food Ltd | Hospitality | 2019 |
| Once Upon a Vine Ltd | Wholesale & retail | 2018 |
| One 2 One Law Limited | Professional & scientific | 2012 |
| One 2 One Legal LLP | | 2012 |
| One Call Consultants Ltd | Administrative & support | 2016 |
| One Call Waste Ltd | Water & waste | 2009 |
| One Cure Medicals Limited | Health & social care | 2024 |
| One Fletcher Gate RTM Company Limited | Households | 2006 |
| One Focus (Leeds) Limited | Hospitality | 2023 |
| One Foot After the Other Limited | Information & communication | 2011 |
| One Formation Leeds CIC | Education | 2025 |
| One Funnel LAB Ltd | Wholesale & retail | 2026 |
| One Global Solutions Limited | Professional & scientific | 2008 |
| One Heart Limited | Hospitality | 2010 |
| One Hundred and Eighty Seven Ltd | Real estate | 2017 |
| One Joinery Ltd | Manufacturing | 2020 |
| One Kitchen for ALL Ltd | Hospitality | 2019 |
| One Leisure Group Ltd | Other services | 2023 |
| One Leisure Saltaire Ltd | Hospitality | 2023 |
| One Level Group Ltd | Wholesale & retail | 2026 |
| One Loft Specialist Racing Limited | Agriculture & fishing | 2024 |
| One Love Leeds Ltd | Other services | 2025 |
| One Medical Europe Limited | Health & social care | 2018 |
| One Medical Limited | Health & social care | 2018 |
| One Medical Otley Limited | Health & social care | 2018 |
| One Medical Properties LLP | | 2005 |
| One Medical Technologies Limited | Health & social care | 2018 |
| One Medicare Europe Limited | Construction | 2009 |
| One Medicare Ltd | Health & social care | 2002 |
| One Medicare Services LLP | | 2005 |
| One Medicare T/A One Primary Care LLP | | 2006 |
| One Mortgages & Protection Limited | Financial services | 2016 |
| One Oak Ventures Ltd | Real estate | 2023 |
| One Prime London Limited | Professional & scientific | 2012 |
| One Red Kite Limited | Professional & scientific | 2012 |
| One Salon Ltd | Other services | 2024 |
| One Shot Construction Limited | Construction | 2019 |
| One Sixty Holdings Limited | Financial services | 2017 |
| One Skin Aesthetics Ltd | Other services | 2024 |
| One Sleep Trading Limited | Wholesale & retail | 2025 |
| One Space Facilities Management Limited | Real estate | 2021 |
| One Springwell Gardens Limited | Construction | 2019 |
| One Step Ahead Limited | Education | 2016 |
| One Step Back Limited | Information & communication | 2023 |
| One Step Beyond Lofts Ltd | Construction | 2025 |
| One Stop Automobiles Ltd | Wholesale & retail | 2026 |
| One Stop Garage (Yorkshire) Ltd | Wholesale & retail | 2023 |
| One Stop Legal Hub Ltd | Financial services | 2025 |
| One Stop Rentals Ltd | Administrative & support | 2023 |
| One Stop Shop E-Commerce Limited | Wholesale & retail | 2024 |
| One Stop Tyres 24/7 Ltd | Wholesale & retail | 2026 |
| One Stop Tyres Yorkshire Ltd | Wholesale & retail | 2026 |
| One Store Direct Limited | Manufacturing | 2024 |
| One T Holdings Limited | Financial services | 2022 |
| One Time Delivery Ltd | Transport & logistics | 2026 |
| One Touch Systems Ltd | Information & communication | 2023 |
| One Twenty Eight Limited | Information & communication | 2018 |
| One Two Three Dental Limited | Health & social care | 2008 |
| One UP Digital Ltd | Professional & scientific | 2020 |
| One Vision Bradford Limited | Wholesale & retail | 2018 |
| One Vision Group Limited | Wholesale & retail | 2015 |
| One Vision Heck Limited | Wholesale & retail | 2019 |
| One Vision Heckmondwike Limited | Wholesale & retail | 2016 |
| One Vision Holdings Limited | Financial services | 2015 |
| One Vision Kirkstall Limited | Wholesale & retail | 2018 |
| One Vision Laboratory Limited | Wholesale & retail | 2016 |
| One Vision Mayo Limited | Wholesale & retail | 2016 |
| One Vision Victoria Limited | Wholesale & retail | 2018 |
| One Way Civil Engineering Ltd | Construction | 2022 |
| One-Over-Four Ltd | Professional & scientific | 2024 |
| One-Tent Properties Limited | Financial services | 2025 |
| ONE10GLOBALEDU Limited | Education | 2024 |
| Onechange | Health & social care | 2025 |
| Onedrive Limited | Information & communication | 2019 |
| Onegeo Limited | Professional & scientific | 2025 |
| Oneko Ltd | Construction | 2025 |
| Onelegion Ltd | Wholesale & retail | 2023 |
| Onemedical Collaborate Limited | Education | 2010 |
| ONEPUGH3 Ltd | Professional & scientific | 2018 |
| Oneself Ltd | Professional & scientific | 2023 |
| Onesixty Fundraising Limited | Administrative & support | 2014 |
| Onespot Video Ltd | Information & communication | 2019 |
| Onesubsea Angola Limited | Manufacturing | 1936 |
| Onesubsea International IP Ltd | Manufacturing | 2018 |
| ONG Property Ltd | Real estate | 2011 |