| Newnight Consulting Limited | Administrative & support | 2017 |
| News Station Ltd | Wholesale & retail | 2026 |
| Newway Mechanical Ltd | Construction | 2020 |
| Nexa Civils & Construction Ltd | Construction | 2026 |
| Nexa Emsworth Limited | Real estate | 2025 |
| Nexlink Ltd | Wholesale & retail | 2024 |
| Nexprop Limited | Real estate | 2024 |
| Next GEN IO Ltd | Manufacturing | 2024 |
| Next GEN Transport Ltd | Transport & logistics | 2024 |
| Next Stone UK Limited | Construction | 2016 |
| Nextgen Interior Solutions Ltd | Construction | 2017 |
| Nextgen Safety Solutions Ltd | Construction | 2025 |
| Nexus AI Apps Ltd | Information & communication | 2026 |
| Nexus Platform Limited | Financial services | 2022 |
| NG Interiors Limited | Construction | 2018 |
| Nggl Holdings Ltd | Financial services | 2025 |
| NGP Consulting Ltd | Professional & scientific | 2025 |
| NH Architects Limited | Professional & scientific | 2022 |
| Niccapotamus Ltd | Real estate | 2024 |
| Niche by Niche Ltd | Financial services | 2023 |
| Nichola Smith Hair Limited | Other services | 2013 |
| Nicholas Beloe Limited | Arts & recreation | 2007 |
| Nicholas Court (Lee-On-Solent) Management Company Limited | Households | 2002 |
| Nichole Laed Ltd | Public administration | 2022 |
| Nick Lang Design Ltd | Professional & scientific | 2019 |
| Nickson Brothers Limited | Wholesale & retail | 2013 |
| Nicky's Beauty Place Limited | Wholesale & retail | 2025 |
| Nico's Main Bakery Limited | Hospitality | 2010 |
| Nicolshire Limited | Professional & scientific | 1979 |
| Nigel Francis Limited | Financial services | 2005 |
| Nightingale Apartments Limited | Construction | 2022 |
| Nightingale Residences Limited | Real estate | 2022 |
| Nightingale Road Management Company Limited | Hospitality | 1983 |
| Nightingales Goldencare Limited | Health & social care | 2002 |
| Nightsearcher Holdings Limited | Financial services | 2017 |
| Nilofar Holdings LLP | | 2023 |
| Nimaf Ltd | Wholesale & retail | 2024 |
| Nimbus IT Works Limited | Administrative & support | 2013 |
| Nime Vaithilingam Gynaecology Ltd | Health & social care | 2014 |
| Nine Acres Park Homes Ltd | Real estate | 2023 |
| Nine Flat Management (Portsmouth) Co. Limited | Households | 1966 |
| Nine One V Group Limited | Wholesale & retail | 2021 |
| Ninety - Nine Transport Limited | Transport & logistics | 2020 |
| NINETY2TWELVE Ltd | Professional & scientific | 2024 |
| Ninja Cleaning Limited | Administrative & support | 2017 |
| Nirvana Freehold Portsmouth Ltd | Households | 2020 |
| Nirvana Mansions (Portsmouth) Limited | Households | 1975 |
| Nirvana Salons Limited | Administrative & support | 2009 |
| Nish KAA Perfect Brows & Beauty Ltd | Other services | 2017 |
| Nistec UK Ltd | Manufacturing | 2008 |
| Niticore Ltd | Information & communication | 2026 |
| NIU Wellness Limited | Other services | 2025 |
| Nixpo Limited | Construction | 2015 |
| NJ Healthcare Ltd | Health & social care | 2016 |
| NK Enables Ltd | Construction | 2025 |
| NKF Cleaning Services Ltd | Administrative & support | 2024 |
| NKM Limited | Wholesale & retail | 2025 |
| NM Assets Limited | Real estate | 2024 |
| NM Commercial Limited | Real estate | 2020 |
| NM Direct Limited | Administrative & support | 2018 |
| NM Investments (Southsea) Limited | Real estate | 2018 |
| NM Projects (Southsea) Limited | Construction | 2020 |
| NM Residential (Southsea) Limited | Real estate | 2023 |
| NMA Mini Market Limited | Wholesale & retail | 2025 |
| NMD Property Limited | Extraterritorial | 2024 |
| Nmrn Hartlepool | Arts & recreation | 2016 |
| Nmrn Operations | Arts & recreation | 2016 |
| Nmrn Services | Arts & recreation | 2014 |
| NMT Logistics Limited | Extraterritorial | 2013 |
| NMV Property Ltd | Real estate | 2026 |
| NO Fuss Engineering Limited | Manufacturing | 2022 |
| NO Plastic Ltd | Arts & recreation | 2020 |
| NO Touch Solutions Ltd | Construction | 2020 |
| NO White Walls Rentals Limited | Real estate | 2014 |
| NO. 26 Dermatology Limited | Health & social care | 2022 |
| NO.66 Cards & Gifts Ltd | Wholesale & retail | 2024 |
| NO1 Energy Solutions Ltd | Construction | 2023 |
| Noahrex Limited | Real estate | 2018 |
| Nobility Logistics International Ltd | Real estate | 2023 |
| Noble Attire Ltd | Wholesale & retail | 2026 |
| Noble Lets Ltd | Households | 2021 |
| Noda Tech Ltd | Information & communication | 2026 |
| Nodum Ltd. | Health & social care | 2019 |
| Noel Wright Architects Ltd | Professional & scientific | 2011 |
| Noexcusess Ltd | Manufacturing | 2021 |
| Nomad Event Catering Limited | Hospitality | 2022 |
| Nonyemary Medical Ltd Ltd | Health & social care | 2021 |
| Noobies Limited | Health & social care | 2016 |
| Noor Spice Limited | Hospitality | 2025 |
| Noorify Ltd | Wholesale & retail | 2025 |
| Nordicsprings Health Limited | Health & social care | 2025 |
| Nordiko Technical Services Limited | Manufacturing | 2003 |
| Norish Group Ltd | Financial services | 2024 |
| Norish Property Ltd | Real estate | 2019 |
| Normandie Taverns Limited | Hospitality | 2017 |
| Normanton Management Limited | Real estate | 2006 |
| Norrington & Company Limited | Other services | 2013 |
| Norse Build Limited | Construction | 2010 |
| North END Bowling Club Limited(The) | Arts & recreation | 1908 |
| North END Portsmouth Ltd | Other services | 2025 |