| New ERA Fundraising Limited | Administrative & support | 2019 |
| New Frontier Property 1 Limited | Real estate | 2024 |
| New Frontier Property 2 Limited | Real estate | 2024 |
| New Frontier Property Holdings Limited | Financial services | 2024 |
| New Frontier Technologies Limited | Information & communication | 2022 |
| New G.B. UK Ltd | Wholesale & retail | 2022 |
| New Middle East Observatory Ltd | Professional & scientific | 2025 |
| New Star Tuition Ltd | Education | 2025 |
| New York Loft Company Limited | Real estate | 1996 |
| Newhall Woods Ltd | Financial services | 2021 |
| Newman Online Limited | Extraterritorial | 1999 |
| Newpowa UK Ltd | Manufacturing | 2022 |
| Nexgenius UK Ltd | Information & communication | 2024 |
| Next Furniture Ltd | Wholesale & retail | 2013 |
| Next Ridge Solutions Ltd | Information & communication | 2025 |
| Next Summit Ltd | Professional & scientific | 2025 |
| NFC Solutions Ltd | Wholesale & retail | 2013 |
| NGN Solutions Ltd | Construction | 2025 |
| Niavon Limited | Real estate | 2021 |
| Nida Ecology Ltd | Professional & scientific | 2026 |
| Nikita Clean Ltd | Administrative & support | 2021 |
| Nikki Bedi Ltd | Arts & recreation | 2011 |
| Nildet Ltd | Wholesale & retail | 2024 |
| Nineshoxxx Entertainment Ltd | Arts & recreation | 2019 |
| Ninti Pharma Ltd | Wholesale & retail | 2025 |
| Nippon Auto Engineering Ltd | Wholesale & retail | 2011 |
| NKD Life Limited | Wholesale & retail | 2016 |
| NL Admin Ltd | Administrative & support | 2009 |
| NLK Consulting Services Ltd | Professional & scientific | 2020 |
| NO Days OFF UK Store Ltd | Wholesale & retail | 2023 |
| Noble Plant Ltd | Administrative & support | 2023 |
| Noblehomebuys Ltd | Wholesale & retail | 2023 |
| Noctis Labs AI Limited | Wholesale & retail | 2025 |
| Noel Holdings Ltd | Financial services | 2024 |
| Nook London Ltd | Hospitality | 2025 |
| Nora Aytch Limited | Wholesale & retail | 2018 |
| Nordway Limited | Administrative & support | 2021 |
| North Horizon Property Ltd | Real estate | 2025 |
| Northern Drivers Ltd | Transport & logistics | 2022 |
| Norwood Green MOT & Service Centre Ltd | Wholesale & retail | 2013 |
| NOT Only Dumplings Ltd | Manufacturing | 2023 |
| NOT3BAD Ltd | Other services | 2025 |
| Notions & Emotions Ltd | Wholesale & retail | 2021 |
| Noureni Fine Collection Ltd | Wholesale & retail | 2022 |
| Nous Infosystems (UK) PVT. Ltd | Information & communication | 2019 |
| Novatib Ltd | Information & communication | 2022 |
| Novelty Pros Ltd | Real estate | 2022 |
| Novex ADS (UK) Ltd | Information & communication | 2023 |
| Novol UK Ltd | Administrative & support | 2016 |
| NR Experts Limited | Health & social care | 2015 |
| Nrht Limited | Professional & scientific | 2018 |
| NSB Structures Ltd | Professional & scientific | 2021 |
| NST - Gnanams Ltd | Wholesale & retail | 2016 |
| NU Start Community Enterprise Ltd | Health & social care | 2008 |
| NU Ventures Technology Ltd | Information & communication | 2016 |
| Nudge Group Ltd | Wholesale & retail | 2016 |
| Nueva Business Consulting Limited | Information & communication | 2015 |
| Numen Fort Ltd | Information & communication | 2021 |
| Nurseday Ltd | Administrative & support | 2025 |
| Nurtech UK Ltd | Professional & scientific | 2017 |
| Nutan Solutions Limited | Real estate | 2021 |
| NUTRAHEALTH365.COM Ltd | Wholesale & retail | 2024 |
| Nutrigenix Labs Limited | Health & social care | 2024 |
| Nutriveda Solutions Ltd | Health & social care | 2024 |
| Nuummo Consulting Ltd | Professional & scientific | 2021 |
| Nvent International (UK) Ltd | Professional & scientific | 2015 |
| Nvent UK Holdings Limited | Financial services | 2017 |
| NW Design Consultancy Ltd | Professional & scientific | 2024 |
| Nyaasa Ltd | Information & communication | 2019 |
| Nycabling Ltd | Information & communication | 2025 |
| O'Driscoll Electrics Ltd. | Energy | 2025 |
| O'Gara-Co Ltd | Professional & scientific | 2016 |
| O'Rourke Studios Ltd | Information & communication | 2026 |
| O.N. Property Services Ltd | Real estate | 2020 |
| O.P.M.E. Limited | Wholesale & retail | 2021 |
| OA Vegetable Limited | Wholesale & retail | 2026 |
| Oak Academy Media Limited | Information & communication | 2018 |
| Oak Applications Limited | Information & communication | 2018 |
| Oak Games Limited | Information & communication | 2019 |
| Oak Smart Solutions Ltd | Information & communication | 2017 |
| Objectword Limited | Professional & scientific | 1991 |
| Ocean Wings Construction Limited | Construction | 2024 |
| Oceanagile Ltd. | Information & communication | 2016 |
| Ocoro Limited | Construction | 2014 |
| Octane & Lock Ltd | Manufacturing | 2025 |
| Octogan Services Limited | Wholesale & retail | 2008 |
| Octopus Care Limited | Health & social care | 2025 |
| Octopus Care PROP1 Limited | Real estate | 2026 |
| Octopus Property Investment and Management Limited | Real estate | 2017 |
| Octus Labs Ltd. | Information & communication | 2018 |
| Ogrody Gardens International Limited | Administrative & support | 2025 |
| OIL Design Limited | Information & communication | 2019 |
| OJ Dealers Limited | Wholesale & retail | 2025 |
| OL Salonna Ltd | Education | 2024 |
| Old Master Press Ltd | Wholesale & retail | 2024 |
| Olelo Ltd | Construction | 2016 |
| Olimpus International Limited | Other services | 2020 |
| Olivers Boatyard Limited | Manufacturing | 2005 |
| Olsights Ltd | Professional & scientific | 2020 |
| Olympus Integrated Services Limited | Wholesale & retail | 2026 |