| Omni Marketing Solutions Limited | Other services | 2025 |
| Omnia Cresco CIC | Education | 2026 |
| Omnicollect Ltd | Manufacturing | 2025 |
| Omnihut Limited | Extraterritorial | 2016 |
| Omnipa Services Ltd | Administrative & support | 2019 |
| Omniport Holdings Limited | Professional & scientific | 2004 |
| Omnisphere Consulting Ltd | Professional & scientific | 2025 |
| Omnisurv AI Ltd | Professional & scientific | 2021 |
| Omnivax Group Ltd | Information & communication | 2026 |
| Omnivers Ltd | Other services | 2023 |
| Omnivex Ltd | Information & communication | 2024 |
| Omnivr Ltd | Information & communication | 2025 |
| Omniweb Ltd | Information & communication | 2014 |
| Omoautemartis Limited | Wholesale & retail | 2023 |
| Omole Auto Car Dealer Limited | Wholesale & retail | 2019 |
| Omontra Ltd | Wholesale & retail | 2024 |
| Ompower Community Yoga CIC | Other services | 2023 |
| Omrao Trading Limited | Financial services | 2021 |
| Omrsstore Ltd | Wholesale & retail | 2023 |
| Omrt Ecommerce Ltd | Wholesale & retail | 2025 |
| Omsr Services Ltd | Hospitality | 2017 |
| OMT Limited | Transport & logistics | 2026 |
| Omtio Ltd | Real estate | 2022 |
| Omtl Investments Limited | Professional & scientific | 2019 |
| ON Behalf Solutions Limited | Administrative & support | 2020 |
| ON Behalf Well-Being Solutions Limited | Health & social care | 2025 |
| ON Demand 247 Ltd | Transport & logistics | 2019 |
| ON Paper Ltd | Manufacturing | 2019 |
| ON Point Branding Ltd | Wholesale & retail | 2019 |
| ON Point Property Maintenance Ltd | Administrative & support | 2019 |
| ON Point Site Services Ltd | Construction | 2022 |
| ON SET Software Ltd | Information & communication | 2016 |
| ON Site Alterations Limited | Wholesale & retail | 2016 |
| ON Target Delivery Ltd | Transport & logistics | 2022 |
| ON Target Magazines Limited | Information & communication | 2012 |
| ON the Ground Limited | Administrative & support | 2014 |
| ON the Mark Surveying Ltd | Professional & scientific | 2015 |
| ON the Wall Installs Ltd | Construction | 2020 |
| ON Time Claim Limited | Administrative & support | 2019 |
| ON Track Group Ltd | Transport & logistics | 2019 |
| On-Par Productions Ltd | Information & communication | 2010 |
| Onaxon Limited | Real estate | 2025 |
| Once Upon a Celebration Limited | Hospitality | 2017 |
| Once Upon a Time Illustrations Limited | Wholesale & retail | 2017 |
| Oncopaedia Ltd | Education | 2017 |
| Ondamatpilates Limited | Other services | 2026 |
| Ondemandworld Limited | Information & communication | 2009 |
| One 6 One Clothing Co Ltd | Wholesale & retail | 2018 |
| One Accountant & Tax Limited | Transport & logistics | 2024 |
| One Accountant SM Ltd | Transport & logistics | 2019 |
| One Answer Ltd | Professional & scientific | 2022 |
| One Answer UK Tax Ltd | Professional & scientific | 2024 |
| One Call ALL Limited | Other services | 2017 |
| One Call Home Improvements Ltd | Construction | 2018 |
| One Call Removals and More Ltd | Administrative & support | 2025 |
| One Cleethorpes Limited | Construction | 2021 |
| One Construction Limited | Construction | 2008 |
| One Consulting Solutions Limited | Administrative & support | 2014 |
| One Creations Europe Ltd | Information & communication | 2018 |
| One Digital DNA Limited | Hospitality | 2008 |
| One Energy Solutions Limited | Administrative & support | 2018 |
| One EVE Inc Ltd | Financial services | 2024 |
| One Family Care Group Limited | Health & social care | 2022 |
| One FIN Limited | Hospitality | 2003 |
| One FOX | Real estate | 2017 |
| One Heart Family Ltd | Extraterritorial | 2020 |
| One Link TV and Media Limited | Information & communication | 2022 |
| One London Recruitment Limited | Administrative & support | 2017 |
| One Luxury Pool Ltd | Construction | 2017 |
| One Nine Design Limited | Professional & scientific | 2012 |
| One Nine Holding Ltd | Professional & scientific | 2016 |
| One Nine Manufacturing Limited | Manufacturing | 2014 |
| One Nine Realty Ltd | Real estate | 2024 |
| One Percent London Ltd | Wholesale & retail | 2025 |
| One Seven Club Limited | Wholesale & retail | 2024 |
| One Simulation UK Limited | Information & communication | 2026 |
| One Slip Ltd | Professional & scientific | 2018 |
| One Source IP Limited | Wholesale & retail | 2005 |
| One Sterling Group Management Limited | Professional & scientific | 2020 |
| One Stop Brewing Limited | Information & communication | 2019 |
| One Stop Hub Ltd | Wholesale & retail | 2026 |
| One Stop Legal Solution Limited | Professional & scientific | 2019 |
| One Stop North London Limited | Wholesale & retail | 2016 |
| One Stop Searches Limited | Information & communication | 2017 |
| One Stop Soloutions Limited | Other services | 2017 |
| One Study Limited | Education | 2015 |
| One to One Dog Training School Limited | Other services | 2024 |
| One Tournament Community Interest Company | Arts & recreation | 2017 |
| One Truck Pony Ltd | Arts & recreation | 2025 |
| One Two Five Property Limited | Construction | 2019 |
| One Voice Healthcare Ltd | Health & social care | 2025 |
| One Wave Films Ltd | Information & communication | 2022 |
| One Way for Real Estate and Trading Ltd | Wholesale & retail | 2025 |
| One Woodland Place Management Company Limited | Households | 2002 |
| One&Yan Ltd | Wholesale & retail | 2025 |
| One-Two Software Limited | Information & communication | 2018 |
| ONE2C Limited | Administrative & support | 2009 |
| ONE2FOUR Accounting Ltd | Professional & scientific | 2018 |
| ONE4SHOP Ltd | Hospitality | 2020 |
| Oneaccountancy Ltd | Professional & scientific | 2009 |