| NHH Lounge Ltd | Hospitality | 2025 |
| Nhks Consultants Limited | Professional & scientific | 2017 |
| Nhlkd Care Limited | Health & social care | 2016 |
| Nhyira Healthcare Ltd | Health & social care | 2022 |
| NI Security Ltd | Information & communication | 2016 |
| Niagem Limited | Information & communication | 2021 |
| Nibgreen | Financial services | 2017 |
| Nice Records Limited | Information & communication | 2021 |
| Niche Careers Consultancy Ltd | Professional & scientific | 2020 |
| Niche Delivered Ltd | Hospitality | 2025 |
| Niche Delivery & Events Ltd | Hospitality | 2026 |
| Niche Equity UK Ltd | Real estate | 2018 |
| Nicholas Jackman Ltd | Education | 2016 |
| Nicholas Trans Limited | Transport & logistics | 2013 |
| Nicholsconsult Ltd | Professional & scientific | 2025 |
| Nick Pelosi Ltd | Transport & logistics | 2016 |
| Nick Swain Limited | Information & communication | 2015 |
| Nick Tyler Training Ltd | Education | 2017 |
| Nick&N Logistics Limited | Transport & logistics | 2019 |
| Nick&Tim Ltd | Transport & logistics | 2018 |
| Nicktrina Ltd | Professional & scientific | 2015 |
| Nico's Bespoke Care Ltd | Health & social care | 2022 |
| Nico's Meals Ltd | Health & social care | 2019 |
| Nicolando Ltd | Wholesale & retail | 2023 |
| Nicole Healthcare Services Limited | Health & social care | 2021 |
| Nicole-Change Ltd | Health & social care | 2022 |
| Nidema Ltd | Construction | 2025 |
| Nidiya Massage Ltd | Information & communication | 2024 |
| Niella Limited | Health & social care | 2019 |
| Nifty Finance Limited | Manufacturing | 1985 |
| Nifty Group Limited | Manufacturing | 2000 |
| Nifty International Limited | Manufacturing | 2000 |
| Niftylift Limited | Manufacturing | 1976 |
| Nigalee Ltd | Real estate | 2025 |
| Nigel Burgess Associates Limited | Professional & scientific | 2006 |
| Nigel Dalley Car Sales Limited | Wholesale & retail | 2016 |
| Nigel Payne Consultancy Ltd | Professional & scientific | 2021 |
| Nigerian Community Milton Keynes Community C.I.C. | Other services | 2025 |
| Nightfox Security (2012) Ltd | Administrative & support | 2012 |
| Nightingale Estates (GB) LLP | | 2007 |
| Nihi Technologies Ltd | Information & communication | 2024 |
| Niik Actuaries Ltd | Financial services | 2018 |
| Niinii Construction Limited | Construction | 2025 |
| Nikaash Management Limited | Professional & scientific | 2007 |
| Nikan Consulting Services Ltd. | Information & communication | 2016 |
| Nikan Digital Systems Ltd | Information & communication | 2023 |
| Nikem Logistic Ltd | Transport & logistics | 2021 |
| Niki Biwati Ltd | Wholesale & retail | 2026 |
| Nikiarf Consulting Limited | Administrative & support | 2012 |
| Nikil Nivas Properties Limited | Real estate | 2023 |
| Nikit Orphanage Limited | Health & social care | 2012 |
| Niklau Commercial Limited | Real estate | 2026 |
| Niklau Holdings Limited | Financial services | 2026 |
| Niklau Residential Limited | Real estate | 2026 |
| Nikon Optical U.K. Limited | Manufacturing | 1997 |
| Nilam Holmes Limited | Other services | 2017 |
| Nile Works Ltd | Real estate | 2025 |
| Nilipeh Ltd | Administrative & support | 2025 |
| Nilisla Ltd | Information & communication | 2023 |
| Nimbleworks Limited | Wholesale & retail | 2024 |
| Nimbus Designs Limited | Wholesale & retail | 1980 |
| Nimbuspay Technologies Ltd | Information & communication | 2024 |
| Nimi Alliance Ltd | Wholesale & retail | 2025 |
| Nimy Creation Limited | Wholesale & retail | 2025 |
| Ninas Store Limited | Wholesale & retail | 2012 |
| Nine Five Tech Ltd | Information & communication | 2026 |
| Nine Homes Ltd | Real estate | 2023 |
| Nine Nieces Group Limited | Real estate | 2024 |
| Nine Three Twenty Limited | Information & communication | 2024 |
| Ninepoint Strategy Ltd | Information & communication | 2026 |
| Nineteen Three Limited | Professional & scientific | 2023 |
| Ninety Nine Group Limited | Professional & scientific | 2023 |
| Ninety Seven Group Limited | Real estate | 2025 |
| Ning-Kum's Ltd | Administrative & support | 2024 |
| Ninng KUM Ltd | Wholesale & retail | 2025 |
| Ninurta Ltd | Professional & scientific | 2006 |
| NIO Spark Ltd | Construction | 2022 |
| Nippon Jidosha International Ltd | Wholesale & retail | 2023 |
| Nipponzan Myohoji | Other services | 2000 |
| Niraxa Ltd | Real estate | 2025 |
| Niro Property Ltd | Real estate | 2025 |
| Nirvana Rose Ltd | Hospitality | 2025 |
| Nirvana Sugars Limited | Arts & recreation | 1995 |
| Niryph Ltd | Information & communication | 2025 |
| NIS Hardware Limited | Wholesale & retail | 2010 |
| NIS Investmend Ltd | Real estate | 2024 |
| NIS Logistics Ltd | Transport & logistics | 2019 |
| Niscayah Holdings Limited | Financial services | 1986 |
| Nishabeauty Ltd | Other services | 2025 |
| Nithsy Private Limited | Other services | 2024 |
| Nithya Foods Ltd | Wholesale & retail | 2021 |
| Nitor Advanced Solutions Limited | Health & social care | 2014 |
| Nitraprime Europe Ltd | Wholesale & retail | 2025 |
| Nitrogym Limited | Education | 2024 |
| Nivelani Ltd | Professional & scientific | 2020 |
| NIVIS2025 Ltd | Real estate | 2025 |
| Nixon Cleaning Services (Milton Keynes) Ltd | Administrative & support | 2019 |
| Niya Renova Ltd | Construction | 2025 |
| NIZ Properties Ltd | Real estate | 2020 |
| NJ Global Enterprise Ltd | Professional & scientific | 2024 |