| Nightingale Harris Limited | Professional & scientific | 2017 |
| Nightingale Parks Limited | Administrative & support | 2012 |
| Nines Casino Ltd | Hospitality | 2024 |
| Nines Cctv Ltd | Administrative & support | 2025 |
| Nines Social Club Ltd | Hospitality | 2025 |
| Nixfixhandiman Ltd | Construction | 2018 |
| NLF Performance Foods Ltd | Wholesale & retail | 2025 |
| NLR Traders Ltd | Wholesale & retail | 2025 |
| NM Brickwork Limited | Other services | 2019 |
| Nmrp Motors Ltd | Manufacturing | 2015 |
| Nnaya Company Ltd | Public administration | 2019 |
| NNL001 Ltd | Manufacturing | 2014 |
| NO More Risks Limited | Professional & scientific | 2026 |
| NO1 BP Sandwich Kiosk Ltd | Hospitality | 2022 |
| Noble Capital Partners Limited | Financial services | 2008 |
| Noir Cosmetics Ltd | Other services | 2017 |
| Noor Al-Ilm Ltd | Wholesale & retail | 2019 |
| Noor Unipick Consultants Ltd | Education | 2026 |
| Nordic Timber Buildings Limited | Manufacturing | 2017 |
| Nordicane Limited | Manufacturing | 1986 |
| Nortek (UK) Limited | Financial services | 1995 |
| Nortek Global Hvac (UK) Limited | Construction | 1978 |
| North Property Rentals Limited | Real estate | 2023 |
| Norton Fire Protection Limited | Public administration | 2014 |
| Notorforver Contracting Ltd | Transport & logistics | 2017 |
| Nova Catering Repairs Ltd | Manufacturing | 2020 |
| Noveau Investments Limited | Other services | 2014 |
| Novnat Tech Ltd | Manufacturing | 2022 |
| NP17 Promotions Limited | Arts & recreation | 2019 |
| NSF Property Management Ltd | Real estate | 2022 |
| NT Software Systems Limited | Information & communication | 2000 |
| NTD Roofs Ltd | Manufacturing | 2025 |
| Nutrilifefoods Ltd | Wholesale & retail | 2024 |
| Nvisionu UK Limited | Health & social care | 2022 |
| Nwad Trading Ltd | Wholesale & retail | 2026 |
| NY Property Services Limited | Construction | 2026 |
| NY Vehicles Ltd | Wholesale & retail | 2024 |
| O&G Accountancy and Bookkeeping Ltd | Professional & scientific | 2024 |
| O'Sullivan Investments Limited | Administrative & support | 2011 |
| O'Sullivan Properties Limited | Administrative & support | 2011 |
| Oak Group Ltd | Real estate | 2022 |
| Oak Healthcare Holding Ltd | Health & social care | 2018 |
| Oakendale Developments Limited | Construction | 1994 |
| OBAISAJJA0 Ltd | Wholesale & retail | 2025 |
| Oblations Contracting Ltd | Transport & logistics | 2016 |
| Ocasmen Ltd | Wholesale & retail | 2018 |
| OCT8 Health Limited | Wholesale & retail | 2025 |
| Octagon Estates Limited | Real estate | 2025 |
| Ogagaoghene Holdings Ltd | Real estate | 2025 |
| Ohenewaa Junior & Co Limited | Real estate | 2023 |
| Oilcan Limited | Extraterritorial | 2014 |
| OJD Investments Limited | Real estate | 2025 |
| OJO Services Ltd | Construction | 2020 |
| OKG Motor Services Ltd | Wholesale & retail | 2024 |
| Old Exchange Darlington Limited | Real estate | 2012 |
| Old Skool Builder Ltd | Construction | 2023 |
| Oldfields Reclamation Ltd | Water & waste | 2008 |
| Oldswinford Property Services Limited | Construction | 2026 |
| Olivia Homes Limited | Real estate | 2022 |
| OLJ Logistics Ltd | Transport & logistics | 2024 |
| OLK Consulting Limited | Professional & scientific | 2023 |
| Olonressal Ltd | Transport & logistics | 2017 |
| Oluwayemi Properties Limited | Real estate | 2024 |
| OLY Ltd | Hospitality | 2022 |
| ON Time Grabbers Limited | Construction | 2018 |
| Once Upon a Present Ltd | Wholesale & retail | 2022 |
| One Four Bravo Limited | Health & social care | 2018 |
| Onedart Manley Limited | Arts & recreation | 2019 |
| Onestop Three Solutions Ltd | Real estate | 2025 |
| Oneworld Money Transfer Ltd | Financial services | 2026 |
| Onidasert Contracting Ltd | Transport & logistics | 2017 |
| Online Game Portal Ltd | Information & communication | 2025 |
| Onmas Care Services Ltd | Administrative & support | 2026 |
| Ontest Limited | Professional & scientific | 2025 |
| Ontime Travel Midlands Ltd | Transport & logistics | 2023 |
| Ooze Construction Ltd | Construction | 2025 |
| Openzim Ltd | Transport & logistics | 2017 |
| Ophan Ltd | Professional & scientific | 2025 |
| Optimise Services Ltd | Construction | 2021 |
| Opus (Midlands) Limited | Construction | 2022 |
| Orange Shop Midlands Ltd | Wholesale & retail | 2025 |
| Orchard 06 Investments Limited | Real estate | 2026 |
| Organised Soul Ltd | Manufacturing | 2021 |
| Origins Trading Ltd | Hospitality | 2023 |
| Orion Cladding Ltd | Manufacturing | 2020 |
| Osys Business Limited | Professional & scientific | 2018 |
| Osys Rowan Limited | Financial services | 2021 |
| Otherton Airfield Limited | Arts & recreation | 2011 |
| Oudana Ltd | Administrative & support | 2024 |
| OUR Dave Transport Limited | Transport & logistics | 2017 |
| OUT of the Box Embroidery Limited | Wholesale & retail | 2026 |
| OUT to Explore ZEN Yoga Ltd | Arts & recreation | 2023 |
| Outgiv Limited | Health & social care | 2018 |
| Outreach Media Solutions Ltd | Professional & scientific | 2023 |
| Outwood Chem Ltd | Wholesale & retail | 2011 |
| Outwood Holdings Ltd | Financial services | 2021 |
| Overdale Holdings Limited | Professional & scientific | 1996 |
| Overlander Group Ltd | Real estate | 2021 |
| Overlander Property Ltd | Real estate | 2024 |
| Overlander Tyres Limited | Wholesale & retail | 2016 |