| Mustard Property Services Limited | Construction | 2022 |
| Musthud Ltd | Manufacturing | 2021 |
| MW Carpentry & Design Ltd | Other services | 2018 |
| My Goal IS ... Limited | Financial services | 2005 |
| Myserv Ltd | Construction | 2015 |
| Myui Ltd | Professional & scientific | 2025 |
| Myveins Limited | Health & social care | 2012 |
| N & N Autoworld Limited | Wholesale & retail | 2006 |
| N. Nano Limited | Arts & recreation | 2023 |
| N695GH Ltd | Extraterritorial | 2024 |
| NAF Group Ltd | Wholesale & retail | 2025 |
| Namib Engineering Services Limited | Professional & scientific | 2020 |
| Nano Resources Limited | Professional & scientific | 2012 |
| Nanteos Limited | Financial services | 2014 |
| Napc Limited | Professional & scientific | 2020 |
| Natasha Pascall Insights Ltd | Information & communication | 2023 |
| National Detailing Academy Limited | Other services | 2016 |
| National Youth Guitar Ensemble Ltd | Arts & recreation | 2018 |
| National Youth Guitar Orchestra Ltd | Arts & recreation | 2018 |
| Nature Capital Limited | Professional & scientific | 2020 |
| Nature Design Ltd | Manufacturing | 2020 |
| Naughty Peanut Ltd | Information & communication | 2014 |
| Nauzan Limited | Wholesale & retail | 2024 |
| ND Send Consultants CIC | Education | 2025 |
| ND Send Specialists Ltd | Education | 2025 |
| NDK Group Limited | Administrative & support | 2020 |
| Neil Casey Associates Ltd | Professional & scientific | 2016 |
| Neil Humphries Consultancy Services Limited | Professional & scientific | 2024 |
| Neil Roberts Associates Limited | Information & communication | 2003 |
| Neocura Ltd | Professional & scientific | 2025 |
| Nerd Alert Ltd | Wholesale & retail | 2024 |
| Neroli and Lavender Ltd | Wholesale & retail | 2025 |
| Nethercote Consultancy Ltd | Professional & scientific | 2018 |
| Netrix IT Solutions Limited | Information & communication | 2018 |
| Nettle Trading Limited | Wholesale & retail | 2022 |
| Nevaya Limited | Information & communication | 2003 |
| New Century Technologies Limited | Professional & scientific | 2007 |
| New East Education Consultancy Co Limited | Education | 2019 |
| New GEN Development Ltd | Professional & scientific | 2007 |
| New Horizons Removals and Storage Ltd | Other services | 2008 |
| New Leaf Leadership Ltd | Education | 2023 |
| New Providence Leisure Limited | Hospitality | 2012 |
| New School of the Anthropocene C.I.C. | Professional & scientific | 2022 |
| Newfield Business Services Limited | Professional & scientific | 2007 |
| Newson Films Ltd | Information & communication | 2022 |
| Next Level Academy Ltd | Arts & recreation | 2024 |
| Next Level Aviation Ltd | Administrative & support | 2024 |
| NFG Ltd | Professional & scientific | 2026 |
| Ngnewity Ltd | Professional & scientific | 2016 |
| Nibblers Direct Ltd. | Wholesale & retail | 2009 |
| Nibblers Snacks Ltd | Wholesale & retail | 2020 |
| Nick Passmore Investments Limited | Professional & scientific | 2015 |
| Nick Price Farming Ltd. | Agriculture & fishing | 2003 |
| Nicola Gardner Ltd | Administrative & support | 2010 |
| Nicola T.C. Ltd | Hospitality | 2014 |
| Niros Ayram Ltd | Transport & logistics | 2025 |
| Niña Cheltenham Ltd | Hospitality | 2026 |
| Njiri UK Ltd | Professional & scientific | 2022 |
| NKS Contracts (Central) Limited | Construction | 1998 |
| NKS Contracts (Holdings) Ltd | Financial services | 2022 |
| NMR Masonry Ltd | Construction | 2024 |
| NOA Finch Limited | Professional & scientific | 2024 |
| Noble Property & Finance Ltd | Financial services | 2026 |
| Nomav Auto Ltd | Wholesale & retail | 2026 |
| Nomidio Limited | Information & communication | 2017 |
| NON Solo Pasta Ltd | Manufacturing | 2018 |
| Norburn Design Ltd | Professional & scientific | 2014 |
| Norcote Administration Ltd | Administrative & support | 2023 |
| North Star Financial Advice Ltd | Financial services | 2014 |
| North Star Financial Planning Ltd | Financial services | 2014 |
| North Swindon Ltd | Real estate | 2009 |
| Northern Exposure UK Ltd | Professional & scientific | 2008 |
| NOT Just Code Ltd | Information & communication | 2014 |
| Nought Technology Limited | Manufacturing | 2020 |
| Nova Care Group (Holdings) Ltd | Health & social care | 2025 |
| Nova Education Solutions Ltd. | Education | 2011 |
| Nptw Limited | Administrative & support | 2019 |
| Nscarborough Consulting Ltd | Professional & scientific | 2023 |
| NSP Takeaway Ltd | Hospitality | 2023 |
| Nugent Project Support Ltd | Information & communication | 2019 |
| Nursery Know HOW Limited | Extraterritorial | 2018 |
| Nutrition by Ellie Ltd | Health & social care | 2023 |
| NWT Property Ltd | Real estate | 2022 |
| Nyra Media Ltd | Information & communication | 2025 |
| O B H Fallen Stock Ltd | Agriculture & fishing | 2013 |
| O Cudmore Limited | Arts & recreation | 2013 |
| O&C Cotswold Trailers Ltd | Administrative & support | 2025 |
| Oaken Court Management Company Limited | Households | 2019 |
| Oakgreen Site Engineering Ltd. | Professional & scientific | 2016 |
| Oaksey Park Golf & Leisure Limited | Arts & recreation | 2020 |
| Oaksey Park Limited | | 1990 |
| Oakway Homes Limited | Construction | 1972 |
| Oast One Limited | Information & communication | 2004 |
| OBS Medical Limited | Professional & scientific | 2000 |
| Octavia's Bookshop Ltd | Wholesale & retail | 2013 |
| Odoki Limited | Health & social care | 2025 |
| OF Colour & Code Ltd | Information & communication | 2016 |
| Oftc Group Limited | Wholesale & retail | 2024 |
| Ogilvy Professional Limited | Other services | 1993 |
| Oink Events Limited | Agriculture & fishing | 2022 |