| Natura Blend Ltd | Wholesale & retail | 2024 |
| Naughtees Clothing Limited | Wholesale & retail | 2014 |
| Navar Limited | Transport & logistics | 2014 |
| Nazlah Consulting Ltd | Professional & scientific | 2024 |
| Nazlah Property Limited | Real estate | 2020 |
| ND Geotechnical and Rail Services Ltd | Professional & scientific | 2025 |
| Neacsu Alex Transport Ltd | Transport & logistics | 2023 |
| Nene Valley Bathrooms & Kitchens Limited | Construction | 2024 |
| Nene Valley Community Services Ltd | Transport & logistics | 2025 |
| Nene Valley Flooring Ltd | Construction | 2019 |
| Nene Valley Leather Limited | Manufacturing | 2018 |
| Nene View Holdings Ltd | Professional & scientific | 2026 |
| Neptune Showers Limited | Extraterritorial | 1988 |
| NET Nightlights Ltd | Wholesale & retail | 2024 |
| New Cafe Bangla Ltd | Hospitality | 2024 |
| New China Town 28 Ltd | Hospitality | 2021 |
| New Dawn Opportunities CIC | Professional & scientific | 2025 |
| New Way Logistics Ltd | Transport & logistics | 2023 |
| Newmarket Security Limited | Construction | 2021 |
| Newport Winter Wonderland Ltd | Arts & recreation | 2024 |
| Newstyle Properties Limited | Real estate | 1990 |
| Newton Bromswold Property Asset Management Limited | Real estate | 2006 |
| Newton Manor Properties Limited | Real estate | 2019 |
| Newton Road Energy Ltd | Energy | 2022 |
| Ngakuta Bay Limited | Professional & scientific | 2023 |
| Nibbs Coaching Limited | Other services | 2024 |
| NIC ERI Trans Limited | Transport & logistics | 2021 |
| Nick Eady Property Developers Limited | Households | 2024 |
| Nico-Rt Ltd | Transport & logistics | 2014 |
| Nidb Ltd | Wholesale & retail | 2024 |
| Nikkita Palmer Designs Ltd | Manufacturing | 2022 |
| Nine One Care Group Ltd | Transport & logistics | 2024 |
| Ninmic Properties Ltd | Real estate | 2023 |
| Nirmal Singh Empire Limited | Wholesale & retail | 2026 |
| NLC Medical & Rescue Services Ltd | Health & social care | 2021 |
| NLH Group Holdings Ltd | Construction | 2023 |
| NO. 6 Developments Limited | Professional & scientific | 2018 |
| Nobel Fast Foods Ltd | Hospitality | 2025 |
| Noble EYE Centre Limited | Health & social care | 2003 |
| Nomsa and Associates Limited | Professional & scientific | 2018 |
| Noriquelondon Limited | Wholesale & retail | 2026 |
| North Tyres Services Ltd | Wholesale & retail | 2017 |
| Northampton Lions Ltd | Arts & recreation | 2026 |
| Northampton Motor Vehicles Ltd | Wholesale & retail | 2018 |
| Northants Event Solutions Ltd | Administrative & support | 2025 |
| Northstars Inline Hockey Club Ltd | Education | 2022 |
| Northtyres Recovery Ltd | Wholesale & retail | 2019 |
| Nortonics Foxtam Limited | Extraterritorial | 1983 |
| Nostalgia Rides Limited | Arts & recreation | 2003 |
| Notla Limited | Education | 2024 |
| NS Weld (UK) Limited | Wholesale & retail | 2023 |
| Nu-Space Renovations Ltd | Administrative & support | 2024 |
| Nuaa Limited | Hospitality | 2026 |
| Nunca Termina Records Limited | Information & communication | 2021 |
| Nutrition and Dietetic Services Limited | Professional & scientific | 1990 |
| Nutshell Creative Marketing Ltd | Administrative & support | 2005 |
| Nuttall Estate Ltd | Hospitality | 2021 |
| Nuttall Property Investments Limited | Real estate | 2016 |
| O'Sullivan Assets Limited | Real estate | 2024 |
| Oakfield Investment Holdings Limited | Real estate | 2024 |
| OG Yummy Food Ltd | Hospitality | 2025 |
| Og's Club (Wellingborough) Limited | Hospitality | 2025 |
| Ohana Travel Ltd | Administrative & support | 2022 |
| Oinic Ltd | Information & communication | 2024 |
| OKN Associates Limited | Professional & scientific | 2019 |
| Olio Energy Services Limited | Professional & scientific | 2018 |
| Olive Herb Catering Ltd | Hospitality | 2020 |
| Olive Roofing & Property Maintenance Limited | Construction | 2020 |
| Olive Tree Associates Ltd | Public administration | 2025 |
| Oliveherb Holdings Limited | Hospitality | 2025 |
| Ollyserve Limited | Construction | 2015 |
| Oluwarantimi Limited | Health & social care | 2013 |
| Omorfia Interior Design Ltd | Administrative & support | 2014 |
| ONE3 Air Conditioning Limited | Energy | 2023 |
| Onestop Autocentre Limited | Wholesale & retail | 2006 |
| Onyx Security Limited | Administrative & support | 2009 |
| Optimove Logistics Ltd | Transport & logistics | 2026 |
| Optio IT Limited | Information & communication | 2026 |
| Orange Instruments Limited | Professional & scientific | 2021 |
| Orbet Roofing Supplies Limited | | 1985 |
| Oriental Gourmet Village Limited | Hospitality | 2014 |
| Oshafi Limited | Construction | 2019 |
| Oval Deene Recruitment Limited | Professional & scientific | 2024 |
| OW Car Sales Limited | Wholesale & retail | 2024 |
| Owen Sexton Limited | Construction | 2017 |
| Oxford Health Exim Limited | Wholesale & retail | 2019 |
| P a Chambers & Associates Limited | Professional & scientific | 2005 |
| P1 Products Ltd | Manufacturing | 2020 |
| P7X Ltd | Professional & scientific | 2022 |
| Pablointhacut Ltd | Other services | 2023 |
| Palace Properties (Rushden) Limited | Real estate | 1956 |
| Pallet Solutions Limited | Manufacturing | 2000 |
| Pamusha Luxproperties Ltd | Real estate | 2022 |
| Panoptic Global Solutions Limited | Wholesale & retail | 2016 |
| Paragon Property Maintenance Ltd | Construction | 2013 |
| Pariah Stories Limited | Wholesale & retail | 2025 |
| Parish Brothers Ltd | Construction | 2025 |
| Park Leathers Limited | Wholesale & retail | 1987 |
| Parmeris LP | | 2022 |
| Partrick Properties LLP | | 2020 |