| Nose Surgeon Ltd | Health & social care | 2020 |
| Nottingham HIP Limited | Health & social care | 2022 |
| Nourish Church Street Limited | Hospitality | 2023 |
| Nouveau Riche Ltd | Administrative & support | 2025 |
| Novak Investments Ltd | Real estate | 2024 |
| Novak Projects Limited | Extraterritorial | 2026 |
| Novak Property Limited | Construction | 2026 |
| Novare Recruitment Ltd | Administrative & support | 2014 |
| Novaren Holdings Limited | Financial services | 2025 |
| Nove Dita Limited | Extraterritorial | 2024 |
| Novus London Limited | Information & communication | 2017 |
| NPN Group Limited | Energy | 2026 |
| NPN Plant Limited | Energy | 2026 |
| NR Anaesthesia Ltd | Health & social care | 2026 |
| Nrol Property Ltd | Real estate | 2024 |
| Nrpartners NO.2 Limited Partnership | | 2007 |
| NSB Solutions Ltd | Health & social care | 2020 |
| Nsno Property Limited | Real estate | 2020 |
| Nsurology Limited | Health & social care | 2025 |
| Nt&As Trustee Limited | Financial services | 2023 |
| NTF Corporate Solutions Limited | Professional & scientific | 2019 |
| NTF Financial Solutions Limited | Professional & scientific | 2008 |
| NTF Group Limited | Extraterritorial | 2024 |
| NTS Property Management & Maintenance Ltd | Construction | 2022 |
| Nubeno Ltd | Health & social care | 2019 |
| Nudge North Ltd | Professional & scientific | 2025 |
| Number Seven House Ltd | Health & social care | 2019 |
| Nuova Impresa Limited | Transport & logistics | 2015 |
| Nursing-Zone Ltd | Administrative & support | 2011 |
| Nuvo Talent Limited | Administrative & support | 2018 |
| Nuvökuche Ltd | Manufacturing | 2024 |
| NV Diagnostics Limited | Health & social care | 2022 |
| NVG Value Pricing Limited | Professional & scientific | 2018 |
| Nwms Group Limited | Professional & scientific | 2022 |
| Nwps Holding Limited | Financial services | 2025 |
| NXT Innovations UK Limited | Information & communication | 2026 |
| NYX Supply Ltd | Wholesale & retail | 2026 |
| O & a Adeyoju Limited | Health & social care | 2019 |
| O & H Project Management Solutions Limited | Professional & scientific | 2013 |
| O & M Solutions LP | | 2010 |
| O B Payments Ltd | Information & communication | 2019 |
| O'Connell Properties Limited | Real estate | 2018 |
| OA Consultant Limited | Health & social care | 2018 |
| OAC Consultants Limited | Information & communication | 2011 |
| OAC Investments Limited | Financial services | 2020 |
| Oak Leaf Dairy Products Limited | Manufacturing | 2015 |
| Oak Nurseries Limited | Wholesale & retail | 2016 |
| Oak Red Consulting Limited | Professional & scientific | 2017 |
| Oakham Dental Studio Limited | Health & social care | 2019 |
| Oaklands Properties and Estates Ltd | Real estate | 2016 |
| Oaks Investing Ltd | Real estate | 2021 |
| Oakura Consulting Ltd | Information & communication | 2021 |
| Oakwood View (Middlewich) Management Company Limited | Households | 2014 |
| OBE Technology Limited | Information & communication | 2005 |
| Oberai Holdings Limited | Real estate | 2022 |
| Oblagon Limited | Professional & scientific | 2022 |
| Ocean Clinic Limited | Health & social care | 2018 |
| Ocean Systems (UK) Limited | Construction | 2002 |
| Oceans Seven PVT Ltd | Wholesale & retail | 2025 |
| OCF LSS Limited | Education | 2022 |
| Octagon Surgery Limited | Health & social care | 2010 |
| Octavian Entertainment Ltd | Administrative & support | 2025 |
| Octopus Change Management Limited | Professional & scientific | 2024 |
| Octox Ltd | Information & communication | 2025 |
| Odland Ltd | Education | 2024 |
| ODM Partners Ltd | Administrative & support | 2022 |
| OE SAP Consultancy Ltd | Information & communication | 2015 |
| OFF Grid Homes Ltd | Real estate | 2013 |
| Off-Site Engineering Limited | Construction | 2017 |
| Ogilvy Hill Ltd | Wholesale & retail | 2020 |
| OJO Clothing Ltd | Wholesale & retail | 2014 |
| Okhuhle Limited | Health & social care | 2024 |
| Old Boot Home Ltd | Wholesale & retail | 2024 |
| Oldham Coliseum Productions Ltd | Arts & recreation | 2014 |
| Oldham Coliseum Theatre Limited(The) | Arts & recreation | 1979 |
| Olesh Holdings Limited | Financial services | 2013 |
| OLF Commodities Limited | Wholesale & retail | 2017 |
| Olico Ltd | Administrative & support | 2017 |
| Olico Property Ltd | Real estate | 2023 |
| Olidex Limited | Professional & scientific | 2018 |
| Olikla Investments Ltd | Real estate | 2021 |
| Olim Social Care Consultancy Ltd | Public administration | 2024 |
| Olisa Medical Ltd | Health & social care | 2021 |
| Oliver IT Consultants Limited | Information & communication | 2008 |
| Oliver's Bar Limited | Hospitality | 2019 |
| Oliver's Club Limited | Other services | 2018 |
| Ollerton Grange (Allerton) Management Company Limited | Households | 2016 |
| Ollie and Darsh Limited | Administrative & support | 2013 |
| OM CVM Ltd | Administrative & support | 2022 |
| OM Recruitment Ltd | Administrative & support | 2015 |
| Omar Al-Nashi Ltd | Real estate | 2015 |
| OME Archive Limited | Wholesale & retail | 2024 |
| Omega Power Solution Ltd | Professional & scientific | 2024 |
| Omega Property Management Limited | Real estate | 2011 |
| Omnia Design Limited | Construction | 2022 |
| Omnium Investments Limited | Financial services | 2026 |
| On-Site Solutions (UK) Limited | Construction | 2002 |
| Oncology Consulting Limited | Health & social care | 2019 |
| One Little Christmas Tree Ltd | Administrative & support | 2021 |
| Oneills Commercial Real Estate Ltd | Real estate | 2025 |