| Micro Vend Supplies LLP | | 2024 |
| Mighty Homes Ltd | Real estate | 2023 |
| Miles Kinloch Ltd | Financial services | 2018 |
| Milestone Mentoring Ltd | Education | 2024 |
| Mill House Construction Services Ltd | Construction | 2026 |
| Mill Road Green Management Company Limited | Professional & scientific | 1999 |
| Milla Management Services Ltd | Professional & scientific | 2007 |
| Miller Brook Ltd | Administrative & support | 2018 |
| Mills Carbon Design Ltd | Professional & scientific | 2024 |
| Mindofafox Ltd | Professional & scientific | 2019 |
| Minton Care (Catherine DE Barnes) Limited | Real estate | 2018 |
| Miracle Tech Ltd | Professional & scientific | 2019 |
| MJ Energy Ltd | Construction | 2015 |
| MJB Interpreting Limited | Professional & scientific | 2012 |
| MJY Property Holdings Limited | Real estate | 2025 |
| MKH Engineering Ltd | Manufacturing | 2024 |
| MM Recruitment Ltd | Administrative & support | 2025 |
| MM Trading Limited | Other services | 2026 |
| MNP Tax Limited | Professional & scientific | 2019 |
| MOD JOE Records LLP | | 2024 |
| Modern Audio Design Limited | Extraterritorial | 2013 |
| Moltons Gear Manufacturing Limited | Manufacturing | 2014 |
| Momken Limited | Professional & scientific | 2024 |
| Montebello Engineering Limited | Information & communication | 2015 |
| Moojah Digital Limited | Information & communication | 2022 |
| More Resources (Northampton) Limited | Transport & logistics | 2010 |
| Morgan-Rose Services Limited | Hospitality | 2015 |
| Mortgage Light Ltd | Financial services | 2012 |
| Motion Leasing Limited | Professional & scientific | 2013 |
| Moto 84 Ltd | Wholesale & retail | 2025 |
| Motus Performance Limited | Professional & scientific | 2015 |
| Movisure Limited | Professional & scientific | 2025 |
| Moylan School of Dance Limited | Arts & recreation | 2009 |
| MP 1 Services Ltd | Transport & logistics | 2022 |
| MR Electric Limited | Professional & scientific | 2013 |
| MSJ Manor Properties Limited | Real estate | 1999 |
| MTC IT Ltd | Information & communication | 2010 |
| Muggle Limited | Real estate | 2022 |
| Mulder Property Conversions Ltd | Real estate | 2024 |
| Multi Wine Limited | Wholesale & retail | 2017 |
| Multibuild Brackley Limited | Construction | 2023 |
| Munnelly Construction Limited | Construction | 2013 |
| Music Saves Ltd | Wholesale & retail | 2025 |
| MW Wilson Limited | Information & communication | 2019 |
| Mwoka Limited | Professional & scientific | 2015 |
| My EV Charge Ltd | Construction | 2022 |
| My Finance Limited | Professional & scientific | 2018 |
| Myblocs.Io Ltd | Information & communication | 2024 |
| Mystor Limited | Administrative & support | 2015 |
| N C B Marking Equipment Limited | Manufacturing | 1983 |
| N W Plumbing & Bathrooms Limited | Construction | 2025 |
| N45H Limited | Real estate | 2023 |
| Narodo Limited | Wholesale & retail | 2019 |
| Native Lighting Ltd | Wholesale & retail | 2019 |
| Natty Rebel Ltd | Administrative & support | 2025 |
| Natures Abundant Health Ltd | Hospitality | 2020 |
| NBF Ltd | Wholesale & retail | 2020 |
| Ncjb Services Ltd | Information & communication | 2022 |
| Nehemiah Ministries | Professional & scientific | 2007 |
| Neighbourly Brands Limited | Financial services | 2015 |
| Neil Painting Master Thatcher Limited | Construction | 2005 |
| Neil Stuchbury Motor Services Limited | Manufacturing | 2002 |
| Neiljacobsproperties Limited | Real estate | 2026 |
| NEL Consultancy Ltd | Other services | 2024 |
| Networking Culture Limited | Professional & scientific | 1988 |
| Neurobility Limited | Health & social care | 2022 |
| New Focus Financial Limited | Financial services | 2017 |
| Nick Wonders Ltd | Wholesale & retail | 2022 |
| Nick’S Domestic Services Ltd | Construction | 2025 |
| NJ Financial Ltd | Financial services | 2020 |
| Njab Consulting Ltd | Other services | 2018 |
| NJT Business Solutions Limited | Professional & scientific | 2010 |
| NNA Surveying Ltd | Professional & scientific | 2020 |
| Noble Container Leasing (UK) Limited | Administrative & support | 2004 |
| Noble Living Space Limited | Real estate | 2017 |
| Nori Shed Ltd | Hospitality | 2021 |
| North Oxon Anaesthesia Services LLP | | 2006 |
| Northampton Plant Hire Ltd | Administrative & support | 2016 |
| Northamptonshire County Association of Local Councils Limited | Other services | 2010 |
| Northants Tanks Limited | Transport & logistics | 2025 |
| Northants Transport Ltd | Transport & logistics | 2024 |
| Northstar Products & Services Limited | Professional & scientific | 2012 |
| Numerarti Ltd | Professional & scientific | 2025 |
| NW Bsl/English Interpreting Limited | Professional & scientific | 2013 |
| NWM Studio Limited | Information & communication | 2025 |
| O W & R J Vernon (Contractors) Limited | Wholesale & retail | 2021 |
| O'Brien 72 Limited | Arts & recreation | 2016 |
| Oak & Stone Construction Ltd | Construction | 2019 |
| Oak & Stone Homes Ltd | Real estate | 2022 |
| Obeah Limited | Information & communication | 2024 |
| OBJECTIV3 Ltd | Professional & scientific | 2024 |
| Ocala Europe Ltd | Administrative & support | 2023 |
| Ockley Brook Limited | Administrative & support | 2012 |
| ODYSSEY360 Ltd | Administrative & support | 2025 |
| OFF the Ground Heels Limited | Professional & scientific | 2015 |
| OHM Distributions Ltd | Wholesale & retail | 2026 |
| Old George Limited | Hospitality | 2013 |
| Old Mill Court Management Company Limited | Administrative & support | 2020 |
| Old Stratford Renovations Ltd | Construction | 2025 |
| Oliac Limited | Wholesale & retail | 2019 |