| Myimove Limited | Administrative & support | 2019 |
| Mymacro Ltd | Wholesale & retail | 2025 |
| N.A.S Aqua Ltd | Real estate | 2024 |
| N.E.W.S Transport & Recovery Ltd | Transport & logistics | 2025 |
| N2HD Limited | Hospitality | 2017 |
| Naillounge Ltd | Other services | 2025 |
| Naje Limited | Manufacturing | 2017 |
| Nambola Limited | Professional & scientific | 2016 |
| Natashabrito-Limited Limited | Health & social care | 2020 |
| Navblue Limited | Transport & logistics | 2002 |
| NCA Trading Ltd | Wholesale & retail | 2019 |
| ND Technical Group Ltd | Construction | 2023 |
| NDH Group International Ltd | Wholesale & retail | 2024 |
| NDL Services Ltd | Health & social care | 2018 |
| Near ME Locksmiths Ltd | Extraterritorial | 2018 |
| Nekkaa Limited | Professional & scientific | 2018 |
| Nela Contractors Ltd | Construction | 2013 |
| Nettleship Group Limited | Information & communication | 2015 |
| Neugate Garden Services Limited | Administrative & support | 2023 |
| New ERA Products Limited | Wholesale & retail | 2014 |
| New Esher Sushi Ltd | Hospitality | 2018 |
| New HAW Community School | Education | 2013 |
| New HAW Dental Limited | Health & social care | 2011 |
| New HAW Library Community Partnership | Arts & recreation | 2012 |
| New HAW Road Limited | Households | 2025 |
| New-Assist Ltd | Wholesale & retail | 2015 |
| Newlion Holdings Limited | Financial services | 2016 |
| Nexage Ltd | Wholesale & retail | 2025 |
| Nexalhealth Care Ltd | Health & social care | 2025 |
| NIC Harmer Group Ltd | Health & social care | 2019 |
| Nice Home Services Limited | Manufacturing | 2018 |
| Nicholson Estates (Century House) Limited | Professional & scientific | 1987 |
| Nightfire Investments Ltd | Real estate | 2025 |
| Nik&Jhon Construction Ltd | Administrative & support | 2018 |
| Nikhil Teeth Consultancy Limited | Professional & scientific | 2019 |
| Ninacare Services Limited | Health & social care | 2019 |
| NJH Pet Care Services Ltd | Professional & scientific | 2022 |
| NMW4S Limited | Wholesale & retail | 2019 |
| NO Hassle Accounts Ltd | Professional & scientific | 2012 |
| NO Matter the Distance Ltd | Manufacturing | 2025 |
| Noble Construction Solutions Ltd | Construction | 2018 |
| Nocsult Ltd | Information & communication | 2014 |
| North Sea Estate Ltd | Real estate | 2025 |
| North Star Leaders Ltd | Professional & scientific | 2020 |
| North Surrey Properties Ltd | Real estate | 2021 |
| Northern Wombat Ltd | Information & communication | 2021 |
| Novi Club Ltd | Administrative & support | 2025 |
| NPS Consultig Limited | Information & communication | 2026 |
| NPS Data Consultancy Limited | Information & communication | 2026 |
| NSC Digital Limited | Information & communication | 2023 |
| Numbers Finance Support & Communication Ltd | Administrative & support | 2009 |
| Numen Studios Ltd. | Information & communication | 2017 |
| Numerics Plus Limited | Administrative & support | 2005 |
| Nutramedix Europe Limited | Wholesale & retail | 2025 |
| Nxtgen BPS Limited | Wholesale & retail | 2023 |
| Oades Property Management Limited | Real estate | 1955 |
| OAF Group Ltd | Information & communication | 2022 |
| Oak Farm Holiday Lets Ltd | Hospitality | 2014 |
| Oak Furniture HUT (UK) Ltd | Wholesale & retail | 2018 |
| Oakdene Residents Management Company Limited | Households | 2004 |
| Oakline Flooring Limited | Wholesale & retail | 2020 |
| Oakridge Construction & Landscaping Ltd | Construction | 2026 |
| Oakstrand Interiors & Joinery Limited | Construction | 2025 |
| Oceanwave Consulting Ltd | Information & communication | 2017 |
| Ocelot Corporate Finance Limited | Professional & scientific | 2017 |
| OCS Property Ltd | Hospitality | 2024 |
| Octopus Consultancy Services Limited | Information & communication | 2024 |
| Octopus Gardens Limited | Construction | 2021 |
| Odds Electrical Services Ltd | Manufacturing | 2026 |
| Odys Strategies Ltd | Information & communication | 2025 |
| Offshore Subsea & Marine Engineering Consultancy (Osmec) Ltd | Professional & scientific | 2026 |
| Ohana's Cafe Bistro Limited | Administrative & support | 2017 |
| Old English Close (Harston) Management Company Limited | Households | 2023 |
| Olectrix Ltd | Construction | 2025 |
| Olive Tree Asset Investments Limited | Real estate | 2023 |
| Oman Green Hydrogen and Chemicals (UK) Private Limited | Financial services | 2022 |
| Oman Green Solutions (UK) Private Limited | Professional & scientific | 2021 |
| ON Point Recovery Limited | Wholesale & retail | 2017 |
| One Surgical Limited | Wholesale & retail | 2019 |
| Oneness Brands Limited | Health & social care | 2020 |
| Ongar Medical Limited | Wholesale & retail | 1996 |
| Open Door Sourcing Limited | Information & communication | 2024 |
| Openstageit Ltd | Information & communication | 2012 |
| Opscale Advisory Ltd | Information & communication | 2025 |
| Optnear Addlestone Ltd | Wholesale & retail | 2023 |
| Optnear Limited | Wholesale & retail | 2012 |
| Optnear New HAW Ltd | Wholesale & retail | 2023 |
| Oras Eastern Samar Ltd | Professional & scientific | 2014 |
| Orbia M&E Services Ltd. | Construction | 2019 |
| Orchard Residential Limited | Households | 2010 |
| Ordies Ltd | Real estate | 2020 |
| Orica Finance UK Limited | Financial services | 2025 |
| Orica Securities UK Limited | Professional & scientific | 1998 |
| Origin Heating Ltd | Construction | 2019 |
| Osma Construction Management Ltd | Construction | 2013 |
| OSO International Limited | Manufacturing | 2011 |
| Otic Software Ltd | Information & communication | 2018 |
| Otterbourne Press Ltd | Information & communication | 2019 |
| Ottershaw Tree Services Ltd | Agriculture & fishing | 2018 |
| Oxhey F.S.E. Limited | Administrative & support | 2013 |