| Ninzoou Limited | Information & communication | 2021 |
| NJ Engineering Limited | Manufacturing | 2024 |
| NJD Welding Ltd | Professional & scientific | 2020 |
| NJH Consulting Ltd | Professional & scientific | 2022 |
| NL2K Limited | Professional & scientific | 2001 |
| NM Meat Consultancy Limited | Wholesale & retail | 2008 |
| NO 1 Junk Street Limited | Water & waste | 2016 |
| NO Strings - Serving the Players Ltd | Wholesale & retail | 2024 |
| No-Tox Ltd | Wholesale & retail | 2025 |
| Noble Hound Grooming Limited | Wholesale & retail | 2024 |
| Noble Renovations & Property Maintenance Ltd | Construction | 2025 |
| Noble-Irwin Associates Ltd | Professional & scientific | 2015 |
| Noctu Recordings Ltd | Wholesale & retail | 2019 |
| Noli Panal Limited | Health & social care | 2025 |
| Noma Capital Limited | Real estate | 2025 |
| Noma Property Limited | Professional & scientific | 2021 |
| Nomad Beer Limited | Hospitality | 2018 |
| Nomistar Ltd | Information & communication | 2009 |
| Nord Creative Ltd | Professional & scientific | 2018 |
| Norfolk & Good Construction & Props Limited | Administrative & support | 2013 |
| Norfolk Lodge Management Company Limited | Households | 2023 |
| North and South Mechanical Ltd | Construction | 2019 |
| North by North East Limited | Real estate | 2019 |
| North Kent Roadstone Limited | Construction | 2004 |
| North Laine Financial Management Ltd | Financial services | 2004 |
| North Parade Residents Association Limited | Administrative & support | 1964 |
| North Pathways Consultancy Limited | Health & social care | 2025 |
| North Sussex Property Investments Limited | Administrative & support | 2010 |
| North Sussex Soccer Academy Ltd | Arts & recreation | 2003 |
| Northdown Close Management Company Limited | Households | 2003 |
| Northfarthing Limited | Professional & scientific | 2022 |
| Northlands 1965 Limited | Extraterritorial | 2014 |
| Northlands Sewage Limited | Households | 2021 |
| Nortonian Ltd | Information & communication | 2022 |
| Nosstek Ltd | Wholesale & retail | 2014 |
| Nothing Hidden Ministries Uk&I | Other services | 2016 |
| Noufar & Partner Global Trading Ltd | Wholesale & retail | 2026 |
| Nourish Move and Maintain Ltd | Other services | 2021 |
| Nova Racing Transmissions Limited | Manufacturing | 1989 |
| Novastar Electrical Limited | Construction | 2016 |
| Novastar Group Limited | Construction | 2023 |
| Novopac (UK) Ltd | Wholesale & retail | 1996 |
| Nowhurst People Advisory Ltd | Extraterritorial | 2025 |
| NP Software & Design Ltd | Information & communication | 2015 |
| NPA Group Ltd | Financial services | 2025 |
| NPD Refurbishments Ltd | Construction | 2022 |
| NPD Tiling and Bathrooms Ltd | Construction | 2024 |
| Npwbmw Ltd | Professional & scientific | 2015 |
| NSY Ltd | Wholesale & retail | 2020 |
| NT Projects Ltd | Administrative & support | 2022 |
| Ntile Ltd | Professional & scientific | 2018 |
| Nube Limited | Real estate | 2021 |
| Nude Goose Ltd | Wholesale & retail | 2020 |
| Nudeday Ltd | Wholesale & retail | 2024 |
| Number One Consultancy Limited | Health & social care | 2023 |
| Nursing Consultancy Ltd | Professional & scientific | 2020 |
| Nutcroft Landscapes Ltd | Construction | 2021 |
| Nutthealthandleisure Limited | Health & social care | 2026 |
| Nuworks Ltd | Information & communication | 2020 |
| NW Enterprise Consultancy Ltd | Professional & scientific | 2020 |
| NW Learning Limited | Education | 2013 |
| O & G Property Limited | Real estate | 2016 |
| O Williams Financial Services Ltd | Financial services | 2021 |
| O'Rourke Coach Trimmers Limited | Wholesale & retail | 2003 |
| O'Rourke Supplies Limited | Manufacturing | 2016 |
| O'Sullivan Farms Limited | Agriculture & fishing | 1997 |
| O1 Jets Ltd | Administrative & support | 2020 |
| OA Test Consulting Limited | Professional & scientific | 2014 |
| Oak and Lavender Ltd | Manufacturing | 2022 |
| Oak Ridge Books Ltd | Wholesale & retail | 2025 |
| Oakendene Estates Limited | Real estate | 1965 |
| Oakhill Hospitality Limited | Hospitality | 2025 |
| Oakhill Systems Limited | Real estate | 1980 |
| Oaklands External Management Company Limited | Real estate | 2007 |
| Oakleyflats RTM Limited | Households | 2018 |
| Oakmasters Group Limited | Financial services | 2016 |
| Oakshire Consulting Limited | Professional & scientific | 2022 |
| Oaktree Farm Care Limited | Health & social care | 2012 |
| Oakvale Homes Limited | Real estate | 2019 |
| Oakwood Construction and Developments Ltd | Construction | 2016 |
| Oakwood Design Group Ltd | Construction | 2026 |
| Oakwood School (Holdings) Limited | Real estate | 1965 |
| OBR Projects Limited | Professional & scientific | 2014 |
| Ocapio Ltd | Health & social care | 2018 |
| Occupational Therapy North West Ltd | Health & social care | 2011 |
| Ocean Independence UK Limited | Administrative & support | 2005 |
| Ocean Nayee Consultancy Limited | Other services | 2024 |
| Oceanic Wingsails Ltd | Manufacturing | 2016 |
| Oceans of Goodness Limited | Wholesale & retail | 1998 |
| OCG Mortgages Ltd | Financial services | 2022 |
| Octanorm Limited | Extraterritorial | 1980 |
| Octanova Consulting Limited | Professional & scientific | 2023 |
| Octopus Trading Limited | Information & communication | 2010 |
| Octopus Wellness Ltd | Wholesale & retail | 2024 |
| Octotech Ltd | Other services | 2015 |
| Oculus (Holdings) Limited | Professional & scientific | 2013 |
| Oculus Wealth Management (Manchester) Limited | Financial services | 2023 |
| Oculus Wealth Management Limited | Financial services | 2013 |
| ODB Construction Limited | Construction | 2016 |
| ODR Property Limited | Construction | 2025 |