| Nomsa's Services Limited | Health & social care | 2018 |
| Nordic Packaging and Container Holdings Limited | Administrative & support | 2016 |
| Nordica Studios Ltd | Real estate | 2022 |
| Normanson Roofing Limited | Construction | 2014 |
| Normcor Ltd | Professional & scientific | 2018 |
| Norra London Ltd | Wholesale & retail | 2025 |
| North Northamptonshire Community Education CIC | Education | 2024 |
| North Northants Music Festival Ltd | Arts & recreation | 2022 |
| North Northants Social Enterprise Network CIC | Administrative & support | 2025 |
| North Sands Financial Management Limited | Professional & scientific | 2020 |
| Northall Investments Limited | Real estate | 1945 |
| Northampton Estates Limited | Real estate | 2022 |
| Northampton Film Festival Limited | Information & communication | 2022 |
| Northampton Motorcycle Sports Club Limited | Arts & recreation | 2004 |
| Northampton Scuba School Ltd | Wholesale & retail | 2025 |
| Northamptonshire Dog Training School Limited | Administrative & support | 2026 |
| Northamptonshire Domestic Appliance Services Ltd | Manufacturing | 2013 |
| Northamptonshire Electrical Consulting Limited | Construction | 2013 |
| Northamptonshire Electrical Contractors Limited | Construction | 2012 |
| Northamptonshire Mountaineers Limited | Hospitality | 1963 |
| Northamptonshire Properties Ltd | Real estate | 2015 |
| Northamptonshire Young Rider Academy Ltd | Agriculture & fishing | 2020 |
| Northants Drainage Limited | Administrative & support | 2007 |
| Northants & MK Sling Library CIC | Health & social care | 2022 |
| Northants Advertising Ltd | Professional & scientific | 2018 |
| Northants Blinds Ltd | Manufacturing | 2023 |
| Northants Building Co Ltd | Construction | 2021 |
| Northants Cabling & Data Solutions Ltd | Information & communication | 2024 |
| Northants Care Ltd | Administrative & support | 2025 |
| Northants County Kitchens Limited | Administrative & support | 2010 |
| Northants Electrical Solutions Ltd | Construction | 2020 |
| Northants Futsal Ltd | Education | 2025 |
| Northants Groundcare Ltd | Administrative & support | 2022 |
| Northants Kids Shoes Ltd | Wholesale & retail | 2023 |
| Northants Media Walls Limited | Construction | 2025 |
| Northants Optical Services Ltd | Wholesale & retail | 2017 |
| Northants PAT Testing Ltd | Administrative & support | 2017 |
| Northants Plastering Services Limited | Construction | 2016 |
| Northants Plumbing & Heating Ltd | Construction | 2014 |
| Northants Property Services Limited | Real estate | 2025 |
| Northants Property Solutions Ltd | Construction | 2020 |
| Northants Removals Limited | Transport & logistics | 2012 |
| Northants Services Ltd | Transport & logistics | 2025 |
| Northants Technical Services Limited | Professional & scientific | 2014 |
| Northants Testing Ltd | Professional & scientific | 2010 |
| Northcourse Limited | Professional & scientific | 2005 |
| Northfield Point One Management Company Limited | Real estate | 2004 |
| Northfield Point Two Management Company Limited | Real estate | 2005 |
| Northpoint Strategy Ltd | Professional & scientific | 2023 |
| Northstone Electrical Services Limited | Construction | 2022 |
| Northumberland Road 1960 Limited | Extraterritorial | 2014 |
| Northview Healthcare Limited | Health & social care | 2023 |
| Nosibe Trading Limited | Wholesale & retail | 2025 |
| NOT Just Content Ltd | Professional & scientific | 2025 |
| Nourriture (UK) Limited | Wholesale & retail | 2009 |
| Nouveau Wealth Management Ltd | Financial services | 2010 |
| Nova Properties Development Ltd | Real estate | 2025 |
| Nova Veza Ltd | Administrative & support | 2026 |
| Novel Events Ltd | Arts & recreation | 2013 |
| Novo Subsea Limited | Professional & scientific | 2026 |
| Nozinhle Dube Ltd | Health & social care | 2021 |
| NPR (Corby) Holdings Limited | Financial services | 2012 |
| NR Civils Ltd | Construction | 2022 |
| NRH Scaffolding Ltd | Construction | 2023 |
| NRX Properties Group Limited | Real estate | 2025 |
| NS Alliance Ltd | Wholesale & retail | 2026 |
| Ns-Uk Group (Northern) Limited | Administrative & support | 2020 |
| Ns-Uk Security Limited | Administrative & support | 2020 |
| Nsngw Ltd | Health & social care | 2022 |
| Nuline Training Ltd | Wholesale & retail | 2023 |
| Numerical Books Ltd | Professional & scientific | 2012 |
| Nuno Ltd | Professional & scientific | 2025 |
| Nurse on Hand Ltd | Health & social care | 2025 |
| Nutherm Limited | Manufacturing | 1985 |
| Nutura Ltd | Wholesale & retail | 2022 |
| Nuve Jewels Ltd | Manufacturing | 2025 |
| NVS7 Ltd | Transport & logistics | 2023 |
| Nyakoga Ltd | Health & social care | 2020 |
| Nyasha Wellness Ltd | Health & social care | 2025 |
| O & N Dalziel Limited | Construction | 2013 |
| O N Transport Limited | Transport & logistics | 2022 |
| O'Sullivan Financial Planning Ltd | Financial services | 2017 |
| Oak and Stones Estates Ltd | Real estate | 2026 |
| Oak Court (NN9) RTM Company Limited | Households | 2024 |
| Oak News Limited | Information & communication | 2025 |
| Oak Rock Capital Limited | Administrative & support | 2021 |
| Oakland Construction (2003) Limited | Construction | 2003 |
| Oakley Bush Solar Limited | Energy | 2024 |
| Oakley Road Garage (Corby) Limited | Wholesale & retail | 1960 |
| Oakley Rose Property Limited | Real estate | 2024 |
| Oakley Transport Management Ltd | Transport & logistics | 2020 |
| Oaksmiths Limited | Construction | 2019 |
| Oaktree Contracts Ltd | Administrative & support | 2022 |
| OB Dent Ltd | Health & social care | 2024 |
| Obany Ltd | Information & communication | 2011 |
| Obeyer Ltd | Arts & recreation | 2024 |
| Object Projects Ltd | Wholesale & retail | 2019 |
| Objets DU Desir Limited | Wholesale & retail | 2013 |
| OC Construct Ltd | Construction | 2026 |
| Ocean Bay Fish & Chips Ltd | Hospitality | 2022 |