| Nigel Grimes Wellbeing Ltd. | Health & social care | 2020 |
| Nightingale Advisory Limited | Professional & scientific | 2023 |
| Nile Training Centre Ltd | Construction | 2020 |
| Nimble Brands Limited | Professional & scientific | 2010 |
| Nine Lion Gate Gardens Management Limited | Households | 1982 |
| Nine Sutton Freehold Limited | Real estate | 2025 |
| Nine Sutton Managing Agent Limited | Real estate | 2025 |
| Ninety Five Bistro Limited | Hospitality | 2021 |
| Ninety One Estates Ltd | Construction | 2024 |
| Nirvu Limited | Arts & recreation | 2012 |
| Nisha Aggarwal Limited | Professional & scientific | 2017 |
| Nive & Vaish Limited | Real estate | 2022 |
| Njinga Cycling Limited | Arts & recreation | 2014 |
| Njkc Ltd. | Information & communication | 2014 |
| Nkar 1 Limited | Hospitality | 2025 |
| Nkar Limited | Hospitality | 2024 |
| NKB Estates Limited | Real estate | 2021 |
| NL Healthcare Limited | Wholesale & retail | 2013 |
| NLK Innovative Solutions Ltd | Arts & recreation | 2024 |
| NNM Soundproofing Limited | Construction | 2022 |
| NO Worries Company Services Limited | Professional & scientific | 2005 |
| NO Worries Red Umbrella Ltd | Professional & scientific | 2014 |
| Noahs London Ltd | Real estate | 2020 |
| Nobel Alfred Limited | Health & social care | 2006 |
| Noble & Humble Textile Ltd | Wholesale & retail | 2023 |
| Noble Fire & Building Services Ltd | Construction | 2024 |
| NOE Limited | Arts & recreation | 2013 |
| Noel Animates Ltd | Information & communication | 2026 |
| Nogatti Ltd | Transport & logistics | 2019 |
| Noir Lifestyle Ltd | Wholesale & retail | 2026 |
| Nolan-Sherry & Associates Limited | Professional & scientific | 2013 |
| Nook Student Housing Limited | Extraterritorial | 2018 |
| Norbiton Heating Limited | Construction | 2013 |
| Nordicdna Ltd | Information & communication | 2020 |
| Norfolk Square(Northern Section)Limited | Real estate | 1957 |
| Norina Mackey Ltd | Information & communication | 2026 |
| Norse Code Ltd | Information & communication | 2020 |
| Norsedan Limited | Construction | 1993 |
| Norson Renovations Limited | Construction | 1998 |
| North Star Infosec Ltd | Information & communication | 2025 |
| Northbury Lane (Twyford) Management Company Limited | Administrative & support | 2010 |
| Northview Willows Ltd | Real estate | 2018 |
| Nosa Osifo Ltd | Construction | 2026 |
| NOT My Circus Ltd | Information & communication | 2021 |
| Noteful Technologies Ltd | Information & communication | 2021 |
| Notua Saint Albans Limited | Real estate | 2021 |
| Nous Ventures Limited | Financial services | 2025 |
| Nouveau IT Consulting Limited | Information & communication | 2016 |
| Nova Fire & Security Ltd | Administrative & support | 2020 |
| Nova Mining UK Limited | Financial services | 2026 |
| Novalis General Partners Ltd | Financial services | 2018 |
| Novas Architects Ltd | Professional & scientific | 2025 |
| Novera Advisors Ltd | Professional & scientific | 2025 |
| Novisto Ltd | Information & communication | 2026 |
| Novotech Clinical Research UK Limited | Professional & scientific | 2021 |
| Noya Clinic Ltd | Health & social care | 2026 |
| Npospay Limited | Wholesale & retail | 2021 |
| NR Retail Ventures Ltd | Wholesale & retail | 2024 |
| Nrjm Limited | Health & social care | 2015 |
| NS Logistics Limited | Information & communication | 2011 |
| NS5 Football Ltd | Education | 2024 |
| Nsimba Services Limited | Construction | 2025 |
| Nslt Consulting Limited | Professional & scientific | 2015 |
| Nssport Limited | Education | 2015 |
| Nssport MJ Ltd | Education | 2022 |
| Nssport SD Ltd | Education | 2022 |
| Nssport SH Ltd | Education | 2022 |
| Nsswim Ltd | Education | 2023 |
| NTE Academy Ltd | Education | 2022 |
| Ntwk Limited | Information & communication | 2015 |
| NUB EL Ltd | Professional & scientific | 2019 |
| Number 7 Alexandra Road (Epsom) Limited | Households | 2009 |
| Number Nine PR Ltd | Professional & scientific | 2024 |
| Numerati Limited | Manufacturing | 1988 |
| Nuonoveshop Co., Ltd | Extraterritorial | 2017 |
| Nusignal Ltd | Construction | 2017 |
| Nuthatch Homes Limited | Real estate | 2017 |
| Nutri Station Ltd | Hospitality | 2017 |
| Nutricademy Limited | Health & social care | 2016 |
| Nuzandey Ltd | Wholesale & retail | 2024 |
| Nyson Ltd | Professional & scientific | 2017 |
| Nyxt AI Ltd | Information & communication | 2025 |
| O G Holdings Limited | Real estate | 2000 |
| O&F Consulting Limited | Administrative & support | 2018 |
| O-Zone Ventures Limited | Administrative & support | 2013 |
| Oakfield Property and Investments LLP | | 2018 |
| Oakford Park (Halnaker) Management Company Limited | Households | 2012 |
| Oakhouse Software Ltd | Information & communication | 2019 |
| Oakington Construction Ltd | Construction | 2025 |
| Oakland Property Management Ltd | Real estate | 2023 |
| Oaklands Care Services Limited | Health & social care | 2003 |
| Oakley Productions Ltd | Information & communication | 2008 |
| Oatridge Ltd | Information & communication | 2020 |
| OB London Holding Ltd | Administrative & support | 2025 |
| OB London Private Management Limited | Real estate | 2026 |
| OB UK Holdings Ltd | Hospitality | 2021 |
| OBE London Limited | Professional & scientific | 2023 |
| OBI Employee Trust Limited | Professional & scientific | 2019 |
| OBI Holdings Limited | Professional & scientific | 2016 |
| OBR Investments Limited | Real estate | 2025 |