| Nimms Enterprise Ltd | Wholesale & retail | 2026 |
| Ninetyfold Foundation | Other services | 2015 |
| Nirex SDH Ltd | Wholesale & retail | 2025 |
| NJ Property Solutions Ltd | Extraterritorial | 2022 |
| NJB Physiotherapy Limited | Health & social care | 2010 |
| NJK (UK) Limited | Professional & scientific | 2007 |
| NKF Properties Limited | Real estate | 2026 |
| Nklinks Limited | Wholesale & retail | 2021 |
| NKN Builders Ltd | Construction | 2020 |
| NLC Autobody Repair Ltd | Wholesale & retail | 2026 |
| Nmartell Properties Ltd | Real estate | 2020 |
| NN Locum Limited | Other services | 2025 |
| NO Seek Ltd | Construction | 2015 |
| Noblepath Ventures Ltd | Real estate | 2024 |
| Nokkio Ltd | Information & communication | 2024 |
| Nordic Transport Ltd | Transport & logistics | 2023 |
| Normagrup UK Limited | Wholesale & retail | 2015 |
| North Street Trading Limited | Wholesale & retail | 2025 |
| Northout Ltd | Wholesale & retail | 2024 |
| Nour International Holdings Limited | Financial services | 2022 |
| Nova Home Healthcare Limited | Health & social care | 2024 |
| Nova Tools Ltd | Manufacturing | 2025 |
| Nova Transport Solutions Ltd | Transport & logistics | 2025 |
| Novaa 2 Global Limited | Wholesale & retail | 2021 |
| NPN Property Maintenance Ltd | Construction | 2025 |
| NR Mobile Autocare Ltd | Wholesale & retail | 2026 |
| NS Construction Solutions Ltd | Construction | 2024 |
| NS Legal Medics Ltd | Health & social care | 2024 |
| NS Medics Ltd | Health & social care | 2023 |
| NS Real Estates Ltd | Real estate | 2024 |
| NSD Financial Services Ltd | Professional & scientific | 2018 |
| NTJ S Construction Ltd | Construction | 2024 |
| NTR Engineering Ltd | Professional & scientific | 2023 |
| Nuel Apartments Ltd | Real estate | 2023 |
| Nura Rafew Logistics UK Limited | Wholesale & retail | 2020 |
| Nurture Care Homes Ltd | Hospitality | 2025 |
| Nuvo Trading Solutions Ltd | Wholesale & retail | 2015 |
| NV Forged Ltd | Wholesale & retail | 2019 |
| NV Holdings Ltd | Professional & scientific | 2019 |
| NV Motorsport Limited | Wholesale & retail | 2010 |
| NVM Engineered Ltd | Wholesale & retail | 2019 |
| NYS School of Barbering Ltd | Administrative & support | 2024 |
| O & P Property Investment Ltd | Financial services | 2022 |
| O'Farrell E Limited | Wholesale & retail | 2015 |
| O.D.A. Electrical Limited | Construction | 2019 |
| Oakléy Construction & Maintenance Ltd | Construction | 2023 |
| Oceans Care Services Ltd. | Wholesale & retail | 2005 |
| OE Solutions Ltd | Education | 2015 |
| OH SOO Social Ltd | Professional & scientific | 2022 |
| Okanui (Nominees) Limited | Extraterritorial | 2006 |
| Oldbury Autogas Ltd | Wholesale & retail | 2020 |
| Oldbury Cafe & Restaurant Ltd | Hospitality | 2025 |
| Oldbury Cafe Limited | Hospitality | 2015 |
| Oldbury Cars Ltd | Wholesale & retail | 2025 |
| Oldbury Crust & Co Ltd | Hospitality | 2025 |
| Oldbury Energy Solutions (UK) Ltd. | Manufacturing | 2021 |
| Oldbury Fabrications Ltd | Manufacturing | 2018 |
| Oldbury Management Services Limited | Administrative & support | 2007 |
| Oldbury Mercedes Sprinter Specialist and Auto Body Repair Ltd | Wholesale & retail | 2026 |
| Oldbury MOT Testing Station Limited | Wholesale & retail | 2022 |
| Oldbury Properties Limited | Administrative & support | 1995 |
| Oldbury Services Limited | Extraterritorial | 2007 |
| Oldbury Social Club Ltd | Hospitality | 2025 |
| Oldbury Upvc Ltd | Wholesale & retail | 2024 |
| Oldbury Wines Limited | Wholesale & retail | 2012 |
| Oligor Ltd | Transport & logistics | 2011 |
| OM Business Solutions Limited | Transport & logistics | 2013 |
| Omel Construction Ltd | Construction | 2024 |
| Omnibox Solutions Ltd | Information & communication | 2023 |
| ON Call Eyecare Ltd | Wholesale & retail | 2023 |
| ON Page Media Limited | Professional & scientific | 2011 |
| ON2011 Transport Services Ltd | Extraterritorial | 2016 |
| One Auto API Limited | Information & communication | 2021 |
| One Stop Cart Limited | Extraterritorial | 2024 |
| One Stop Lettings & Sales Ltd | Real estate | 2018 |
| One the Brayford Ltd | Construction | 2015 |
| One the Brayford Two Limited | Real estate | 2019 |
| Oneworld Services Limited | Other services | 2026 |
| Onighon Heating Services Ltd | Construction | 2024 |
| Online Merchant Limited | Wholesale & retail | 2024 |
| Ontario Ventures Limited | Construction | 2007 |
| Ontoai Ltd | Information & communication | 2024 |
| Onyejiakag Ltd | Health & social care | 2024 |
| Onyx Learning & Development Ltd | Education | 2021 |
| Optima Agencies Limited | Professional & scientific | 2014 |
| Optima Print Limited | Manufacturing | 2002 |
| Options for Life | Health & social care | 1997 |
| Opulent Decor Ltd | Arts & recreation | 2025 |
| Opydee Ltd | Health & social care | 2023 |
| Orbital Business Systems Ltd | Health & social care | 2023 |
| Orbitrade Ltd | Wholesale & retail | 2024 |
| Orchard Veterinary Centre Limited | Professional & scientific | 2013 |
| Oriental Property Management Limited | Real estate | 2020 |
| Orkani Skin Care Products Limited | Manufacturing | 2017 |
| Osborne Simon Limited | Wholesale & retail | 2011 |
| Osip Remuval Ltd | Wholesale & retail | 2021 |
| Otaal Transport Services Ltd | Transport & logistics | 2025 |
| Outside the Box-Creative Thinking Space C.I.C. | Arts & recreation | 2024 |
| Ovenly Klean Limited | Administrative & support | 2018 |
| Owo’S Motor Limited | Wholesale & retail | 2019 |