| OLW Construction Limited | Construction | 2012 |
| Olympia Upholstery Limited | Other services | 2016 |
| Olympian Wellness Ltd | Health & social care | 2025 |
| Olympic Plumbing Heating and Electrical Services Limited | Wholesale & retail | 2007 |
| Olympiq Ltd | Information & communication | 2025 |
| Olympus Technologies (Glos) Limited | Other services | 2002 |
| OM Burger Ltd | Hospitality | 2019 |
| OM Lohan Limited | Wholesale & retail | 2026 |
| OM Mortgages Ltd | Financial services | 2025 |
| OM Networks Ltd | Professional & scientific | 2018 |
| OM Scientific Ltd | Wholesale & retail | 2025 |
| OM Training Hub Ltd | Education | 2024 |
| Oma's Hair & Beauty Ltd | Other services | 2024 |
| Omada Strategy Limited | Administrative & support | 2023 |
| Omar Kamal Entertainment Ltd | Information & communication | 2020 |
| Omar Rentals Limited | Wholesale & retail | 2025 |
| Omar S M General Trading Ltd | Wholesale & retail | 2025 |
| Omar's Auto Repair Ltd | Wholesale & retail | 2024 |
| Omar's Kitchen Ltd | Hospitality | 2018 |
| Omax Solutions Ltd | Professional & scientific | 2011 |
| Ombre Capital Ltd | Construction | 2026 |
| Ombros Solutions Limited | Professional & scientific | 2012 |
| OMC Electrical Site Services Ltd | Construction | 2026 |
| OMD Plastering & Carpentry Limited | Manufacturing | 2022 |
| OME Design Limited | Wholesale & retail | 2022 |
| Omega Collective Ltd | Wholesale & retail | 2025 |
| Omega Consulting It/Av Services Ltd | Information & communication | 2016 |
| Omega Genesis Ltd | Financial services | 2025 |
| Omega Live Ltd | Arts & recreation | 2020 |
| Omega Nebula Ltd | Arts & recreation | 2025 |
| Omega Rose Properties Ltd | Real estate | 2022 |
| Omega Solutions U.K. Ltd | Health & social care | 2015 |
| Omegarose Limited | Real estate | 1984 |
| Ometry Ltd | Professional & scientific | 2018 |
| OMG Venue Limited | Wholesale & retail | 2010 |
| Omgk Digistore Ltd | Wholesale & retail | 2026 |
| OML Property Group Limited | Real estate | 2020 |
| Ommec Direct Ltd | Manufacturing | 2010 |
| Ommi Productions Ltd | Information & communication | 2018 |
| Omnex Consulting Ltd | Professional & scientific | 2025 |
| Omni Digital Limited | Information & communication | 2012 |
| Omni Matrix Group Ltd | Financial services | 2016 |
| Omni Motor Group Ltd | Wholesale & retail | 2023 |
| Omni Productions Ltd | Extraterritorial | 2009 |
| Omni Support Group Ltd | Health & social care | 2021 |
| Omni Training Ltd | Wholesale & retail | 2025 |
| Omni Transport Services Ltd | Transport & logistics | 2022 |
| Omni-Id Limited | Administrative & support | 2007 |
| Omni-Press Limited | Manufacturing | 2021 |
| Omnia Build and Maintenance Limited | Construction | 2025 |
| Omnia People Limited | Administrative & support | 2016 |
| Omnia Property Solutions Limited | Real estate | 2023 |
| Omnifarious Limited | Information & communication | 1998 |
| Omnifera Ltd | Construction | 2013 |
| Omnigenix Limited | Professional & scientific | 2004 |
| Omnipia Consulting Limited | Professional & scientific | 2022 |
| Omniraj Limited | Administrative & support | 2018 |
| Omniversal Gaming Ltd | Manufacturing | 2023 |
| Omolara Productions Limited | Arts & recreation | 2025 |
| Ompimi Ltd | Wholesale & retail | 2024 |
| OMR Construction Ltd | Construction | 2025 |
| OMS International Limited | Professional & scientific | 2019 |
| Omshivay Limited | Wholesale & retail | 2022 |
| Omsi (Equipment) Limited | Administrative & support | 2025 |
| Omsi (Projects) Limited | Professional & scientific | 2025 |
| OMT Bristol Ltd | Hospitality | 2019 |
| Omwater Systems Limited | Water & waste | 2020 |
| ON a Roll Indo Mexican Limited | Hospitality | 2020 |
| ON Care Limited | Health & social care | 2016 |
| ON Drinks Limited | Wholesale & retail | 2014 |
| ON Electric Ltd | Construction | 2024 |
| ON Point Bristol Ltd | Arts & recreation | 2018 |
| ON Point Copywriting Limited | Professional & scientific | 2012 |
| ON Point Developers Ltd | Other services | 2025 |
| ON Point Dist Ltd | Wholesale & retail | 2017 |
| ON Press Technologies Limited | Wholesale & retail | 1999 |
| ON Reflection Ceramics Limited | Wholesale & retail | 2013 |
| ON Site Security Ltd | Administrative & support | 2018 |
| ON Site Sparkle Ltd | Administrative & support | 2020 |
| ON Site Welding (South West) Ltd | Construction | 2014 |
| ON TAP Personnel Limited | Administrative & support | 2026 |
| ON the Brink Arts C.I.C. | Administrative & support | 2021 |
| ON the CUT Limited | Information & communication | 2022 |
| ON the House Mortgages Ltd | Financial services | 2023 |
| ON the Lane Limited | Health & social care | 2019 |
| ON the Level Carpentry Ltd | Construction | 2019 |
| ON the Park Limited | Households | 2002 |
| ON the Pass Limited | Hospitality | 2023 |
| ON the Rocks Property Ltd | Real estate | 2026 |
| ON the Scene Limited | Administrative & support | 2014 |
| ON the Spot Signs Limited | Manufacturing | 2000 |
| ON the UP PR Limited | Professional & scientific | 2024 |
| ON the Wind Ltd | Real estate | 2023 |
| ON Time Cars Bristol Ltd | Transport & logistics | 2025 |
| ON Toast Productions Ltd | Arts & recreation | 2026 |
| ON Y VA (2021) Ltd | Professional & scientific | 2021 |
| ON YA Bike Ltd | Extraterritorial | 2007 |
| ON Your Street Ltd | Real estate | 2025 |
| On-Sight Services Ltd | Professional & scientific | 2024 |
| Onandon Employee Ownership Trustee Limited | Professional & scientific | 2021 |