| M M Restaurants MK Limited | Hospitality | 2026 |
| M Mckenna Signalling Limited | Transport & logistics | 2017 |
| M MOR Trans Ltd | Transport & logistics | 2019 |
| M Nail Collective Ltd | Other services | 2025 |
| M Piciu Trans Ltd | Transport & logistics | 2020 |
| M Purcel Ltd | Transport & logistics | 2013 |
| M R Wicks Ltd | Water & waste | 2012 |
| M Reed Ltd | Information & communication | 2007 |
| M T Automotives Limited | Wholesale & retail | 2007 |
| M Trading Group Holdings Limited | Other services | 2020 |
| M V ETE Ltd | Information & communication | 2010 |
| M W Bodyshop Limited | Wholesale & retail | 2009 |
| M W Graham Electrical Limited | Construction | 2018 |
| M&C Innovations Limited | Construction | 2019 |
| M&D Brickworks (UK) Limited | Construction | 2014 |
| M&E Mills Manufacturing Ltd | Manufacturing | 2022 |
| M&F Bakery Limited | Wholesale & retail | 2022 |
| M&G Courier Ltd | Transport & logistics | 2025 |
| M&G Mortgages Ltd | Financial services | 2014 |
| M&G Trading Ltd | Agriculture & fishing | 2020 |
| M&H Clothing Manufacturing Ltd | Manufacturing | 2021 |
| M&H Fire Protection Ltd | Public administration | 2026 |
| M&I Cafe Ltd | Hospitality | 2025 |
| M&Jl Ltd | Construction | 2022 |
| M&L Custom Bodywork Ltd | Wholesale & retail | 2023 |
| M&M Composites Ltd | Manufacturing | 2025 |
| M&M Evergreen Caterers Limited | Hospitality | 2022 |
| M&M Landscaping Limited | Administrative & support | 2013 |
| M&M Limited Company Ltd | Real estate | 2026 |
| M&M Living Limited | Professional & scientific | 2025 |
| M&M Online Retail Company Ltd | Wholesale & retail | 2026 |
| M&N Creative Ltd | Hospitality | 2025 |
| M&P Consultants Limited | Professional & scientific | 2025 |
| M&P Electrical Installations Ltd | Construction | 2011 |
| M&P Invest Ltd | Real estate | 2019 |
| M&R Drylining Limited | Construction | 2025 |
| M&R Nail Studio Ltd | Other services | 2026 |
| M-Powered Parts Limited | Wholesale & retail | 2025 |
| M. Luther Cars Ltd | Wholesale & retail | 2024 |
| M. Teevan Hire Co. Limited | Construction | 1992 |
| M.A. Lorand Ltd | Transport & logistics | 2016 |
| M.A.A.D Services Ltd | Transport & logistics | 2021 |
| M.A.G Renovations Limited | Real estate | 2025 |
| M.A.R Design and Construction Ltd | Construction | 2020 |
| M.Arch Design Firm Ltd | Professional & scientific | 2026 |
| M.Btl Construction Ltd | Construction | 2024 |
| M.E Consultancy Ltd | Information & communication | 2024 |
| M.E. Billington Ltd | Construction | 2002 |
| M.H.V. Products Limited | Professional & scientific | 1975 |
| M.I.Staples Project & Site Management Limited | Construction | 2014 |
| M.J. Giddings (G.Pak) Limited | Wholesale & retail | 1985 |
| M.J.B Engineering Ltd | Manufacturing | 1986 |
| M.K. Maison Limited | Other services | 2012 |
| M.K. Marking Systems Limited | Manufacturing | 1984 |
| M.K. Multiple Sclerosis Therapy Group Limited | Health & social care | 1993 |
| M.K. Occupational Health Limited | Health & social care | 1996 |
| M.K. Technology Limited | Administrative & support | 1982 |
| M.K.R. Dent Limited | Health & social care | 2018 |
| M.L. Building Renovation Ltd | Construction | 2021 |
| M.L.S Hand Car Wash Ltd | Wholesale & retail | 2019 |
| M.M Construction Ltd | Construction | 2026 |
| M.M Lwazi Limited | Professional & scientific | 2017 |
| M.N.C. Limited | Wholesale & retail | 1993 |
| M.N.Y. Creative Ltd | Professional & scientific | 2026 |
| M.S.E. Projects Limited | Construction | 2020 |
| M.S.G. IT and Software Consultancy Ltd | Wholesale & retail | 2019 |
| M.T General Construction Ltd | Construction | 2021 |
| M.T.M. Chauffeurs Limited | Transport & logistics | 2001 |
| M.T.V Ventures Limited | Transport & logistics | 2013 |
| M.Y International Consulting Ltd | Professional & scientific | 2025 |
| M2G TRC Ltd | Professional & scientific | 2024 |
| M3 Property Maintenance Limited | Construction | 2015 |
| M3 Wellbeing Limited | Real estate | 2020 |
| M41 Renovations Ltd | Construction | 2026 |
| M4LK Cars Limited | Wholesale & retail | 2025 |
| M5 External Cleaning & Resin Driveways Limited | Other services | 2020 |
| M54 Garage Ltd | Wholesale & retail | 2019 |
| M5L Consulting Limited | Information & communication | 2026 |
| M77 Corporation Support Limited | Administrative & support | 2016 |
| M77 J39 Limited | Professional & scientific | 2025 |
| MA City Consultants Limited | Professional & scientific | 2023 |
| MA Cost Consulting Limited | Professional & scientific | 2009 |
| MA Investment Management Holdings Limited | Financial services | 2024 |
| MA Medicare Ltd | Health & social care | 2025 |
| MA Shiv SAI Solutions Ltd | Information & communication | 2011 |
| MA Transport London Limited | Administrative & support | 2024 |
| MA.91 Ltd | Administrative & support | 2022 |
| MAA U Catering and Services Limited | Hospitality | 2021 |
| Maab Connect Ltd | Wholesale & retail | 2018 |
| Maaepic Services Limited | Administrative & support | 2024 |
| Maajinakar Limited | Manufacturing | 2014 |
| Maaree Ltd | Wholesale & retail | 2016 |
| Maarif Enterprises Ltd | Administrative & support | 2020 |
| Maarvik Ltd | Information & communication | 2023 |
| Mabbi Limited | Wholesale & retail | 2021 |
| Mabel Adamtey Company Ltd | Health & social care | 2021 |
| Mable Homes Limited | Real estate | 2023 |
| Mable Therapy Ltd | Health & social care | 2015 |
| Mabs Properties Limited | Real estate | 2020 |
| Mabs Technology Limited | Information & communication | 2010 |