| M F Jones & Co Limited | Professional & scientific | 2003 |
| M Fewtrell Ltd | Arts & recreation | 2026 |
| M Heath Plumbing Ltd | Construction | 2026 |
| M Home Renovations Ltd | Construction | 2019 |
| M HOW Limited | Construction | 2014 |
| M I R Z Ltd | Transport & logistics | 2022 |
| M J B Accountants Limited | Professional & scientific | 2002 |
| M J Goddard Design Consultancy Ltd | Professional & scientific | 2021 |
| M J Law Electrical Limited | Construction | 2016 |
| M J Law Properties Ltd | Real estate | 2024 |
| M J Lever Groundworks and Game Ltd | Administrative & support | 2021 |
| M J Venture Holdings Limited | Wholesale & retail | 2025 |
| M Lennartsson Turner Limited | Professional & scientific | 2015 |
| M M K Civil Engineers Ltd | Construction | 2012 |
| M Martins Services Ltd | Transport & logistics | 2021 |
| M N a Motors Ltd | Wholesale & retail | 2022 |
| M O'Flanagan & Sons Ltd | Professional & scientific | 2009 |
| M Omar Express Couriers Ltd | Transport & logistics | 2023 |
| M P J Enterprises Ltd | Hospitality | 2000 |
| M Pali Construction Ltd | Construction | 2021 |
| M Smith Consulting Services Ltd | Professional & scientific | 2025 |
| M Snell Limited | Information & communication | 2017 |
| M Susans Building Ltd | Construction | 2002 |
| M Sweeney Contractors Limited | Construction | 2017 |
| M Sykes Developments Limited | Construction | 2010 |
| M T M Fleet Maintenance Limited | Wholesale & retail | 2021 |
| M Thomas Haulage Ltd | Transport & logistics | 2025 |
| M W Auto Centre Limited | Wholesale & retail | 2023 |
| M Wala Bar & Grill Ltd | Hospitality | 2026 |
| M Weatherley & Sons Ltd | Construction | 2012 |
| M&A 786 Limited | Hospitality | 2020 |
| M&A Accountants and Safe Secure Tax Specialists Ltd | Professional & scientific | 2026 |
| M&A Car Shop Ltd | Wholesale & retail | 2026 |
| M&A Motors Northants Ltd | Wholesale & retail | 2019 |
| M&A Optima Cleaning Ltd | Administrative & support | 2026 |
| M&A Proctor Holdings Limited | Construction | 2025 |
| M&A Property Services (Northants) Limited | Real estate | 2021 |
| M&C Clean Ltd | Administrative & support | 2025 |
| M&C Haulage Ltd | Transport & logistics | 2019 |
| M&C Property Management UK Limited | Administrative & support | 2010 |
| M&C Spedition Ltd | Transport & logistics | 2025 |
| M&D Drivers Ltd | Transport & logistics | 2016 |
| M&E Residents Ltd | Real estate | 2025 |
| M&E Services Ltd | Construction | 2025 |
| M&E&N Limited | Transport & logistics | 2019 |
| M&F Logistics Ltd | Transport & logistics | 2025 |
| M&G Brickwork and Cleaning Ltd | Construction | 2022 |
| M&Gsolonaru Ltd | Transport & logistics | 2024 |
| M&K Renovation and Cleaning Properties Ltd | Construction | 2024 |
| M&L Estates LLP | | 2021 |
| M&L Locksmiths Limited | Construction | 2019 |
| M&M Courier Logistics Ltd | Transport & logistics | 2017 |
| M&M Innovation Limited | Manufacturing | 2016 |
| M&M Interior Designs Ltd | Construction | 2020 |
| M&M Story Ltd | Transport & logistics | 2025 |
| M&N Elite Glow Ltd | Other services | 2026 |
| M&N Partnership Ltd | Hospitality | 2026 |
| M&O Auto Services Ltd | Other services | 2019 |
| M&P Property Services Limited | Real estate | 2026 |
| M&R Trans Ltd | Transport & logistics | 2020 |
| M&Roman Beauty Academy Ltd | Administrative & support | 2024 |
| M&S Autoworks Ltd | Wholesale & retail | 2024 |
| M&S Grinyer Pools Ltd | Construction | 2023 |
| M&V Courier Ltd | Transport & logistics | 2025 |
| M-Plan Construction Limited | Professional & scientific | 2013 |
| M-Zhan Ltd | Transport & logistics | 2019 |
| M. a. Dobson Limited | Wholesale & retail | 2014 |
| M. F. Quinn Limited | Construction | 2020 |
| M. Faber Ltd | Wholesale & retail | 2018 |
| M. K. Flats (NO.1) Limited | Households | 1981 |
| M. R. S. Automotive Ltd | Wholesale & retail | 2018 |
| M.A.G Properties Ltd | Real estate | 2025 |
| M.A.K. Food Processing Solutions Ltd | Hospitality | 2015 |
| M.A.M. Transport Services Limited | Transport & logistics | 1997 |
| M.A.S. Engineering Ltd | Manufacturing | 2003 |
| M.D. Chiropractic Solutions Limited | Health & social care | 2025 |
| M.E. Brown & SON Ltd. | Professional & scientific | 2008 |
| M.I.C. Driving Ltd | Transport & logistics | 2014 |
| M.J.Pavitt Limited | Administrative & support | 2016 |
| M.J.R. Tipper & Site Services Limited | Wholesale & retail | 1996 |
| M.K Cars (Northampton) Ltd | Transport & logistics | 2020 |
| M.K.A Transport Ltd | Transport & logistics | 2019 |
| M.M.A.S. Northampton Construction Limited | Transport & logistics | 2015 |
| M.Price Limited | Construction | 1958 |
| M.Puscas Limited | Manufacturing | 2024 |
| M.R.S. Spraytech Ltd | Construction | 2022 |
| M.S. Laboratories Limited | Other services | 1990 |
| M.Siyar Ltd | Hospitality | 2019 |
| M.Speed Engineering Ltd | Professional & scientific | 2018 |
| M17HSM Ltd | Administrative & support | 2026 |
| M2 Estates Ltd | Real estate | 2022 |
| M2 Innovation Ltd | Wholesale & retail | 2024 |
| M25 Autos Ltd | Wholesale & retail | 2021 |
| M3 Strategic Marketing Ltd | Information & communication | 2010 |
| M3SURVEYS Ltd | Professional & scientific | 2025 |
| M3V Group Ltd | Professional & scientific | 2018 |
| M4M Ltd | Construction | 2017 |
| M75 Limited | Administrative & support | 2024 |
| M@D Properties Ltd | Real estate | 2020 |
| MA & H Properties Limited | Real estate | 2025 |