| M-Tech GAS and Plumbing Ltd | Construction | 2025 |
| M. Murfin & Sons Limited | Wholesale & retail | 2011 |
| M.& M.Burley Limited | Real estate | 1964 |
| M.A Carz Ltd | Transport & logistics | 2025 |
| M.A Legal Solutions Limited | Professional & scientific | 2025 |
| M.A. Ford Europe Limited | Manufacturing | 1967 |
| M.A. Frost Electrical Services Limited | Administrative & support | 1997 |
| M.A.B. Motors Limited | Wholesale & retail | 2008 |
| M.A.Bond Transport Ltd. | Wholesale & retail | 2011 |
| M.A.O Logistic Ltd | Construction | 2016 |
| M.A.S. Developments (Northern) Limited | Construction | 2017 |
| M.E.A Property Investments Ltd | Households | 2024 |
| M.E.M Homes Limited | Real estate | 2022 |
| M.G. Ward Builders Limited | Construction | 1978 |
| M.Hamza Traders Ltd | Wholesale & retail | 2024 |
| M.J. Shapcott & Co Limited | Professional & scientific | 2003 |
| M.J.& D.Cotterill(Engineers)Limited | Professional & scientific | 1961 |
| M.J.M Services (UK) Ltd | Manufacturing | 2010 |
| M.K,H Removals Ltd | Transport & logistics | 2024 |
| M.Nasir Ltd | Wholesale & retail | 2021 |
| M.O.L.E. International Enterprises Ltd | Financial services | 2018 |
| M.P. BIO Science Limited | Manufacturing | 2007 |
| M.S.L. Sport Services Ltd | Arts & recreation | 2017 |
| M.W. (Polymer Products) Limited | Manufacturing | 1992 |
| M1 Cars Limited | Transport & logistics | 2025 |
| M1&S1 Property Limited | Real estate | 2023 |
| M1TEE Ltd | Real estate | 2005 |
| M2 London Ltd | Professional & scientific | 2018 |
| M2 Medical Limited | Health & social care | 2024 |
| M2C1 Limited | Information & communication | 2015 |
| M2R2 Ltd | Transport & logistics | 2023 |
| M3C Sports Supplies Limited | Wholesale & retail | 2004 |
| M3ERP Ltd | Information & communication | 2018 |
| M4PP Limited | Real estate | 2023 |
| M4TEC Ltd | Wholesale & retail | 2023 |
| M71 Ltd | Wholesale & retail | 2026 |
| M8 Security Limited | Administrative & support | 2025 |
| MA Implant Solutions Ltd | Health & social care | 2026 |
| MA Interim Solutions Limited | Professional & scientific | 2016 |
| MA Products & Services Ltd | Health & social care | 2023 |
| MA Services for Healthcare Limited | Health & social care | 2013 |
| MA Suleman Holdings Limited | Real estate | 2022 |
| MA026 Limited | Financial services | 2025 |
| MA568 Limited | Hospitality | 2018 |
| MAA Tech Support Ltd | Information & communication | 2017 |
| Maadi Properties Limited | Real estate | 2018 |
| Maak Medical Limited | Health & social care | 2022 |
| Maaksa Ltd | Wholesale & retail | 2026 |
| Maan Motors Ltd | Wholesale & retail | 2026 |
| MAB (Derby) Limited | Extraterritorial | 2006 |
| MAB Financial Planning Limited | Extraterritorial | 2010 |
| MAB Private Finance Ltd | Extraterritorial | 2008 |
| MAB Process Welding Ltd | Professional & scientific | 2023 |
| MAB1 Limited | Extraterritorial | 2016 |
| Mabhena Trades Limited | Manufacturing | 2024 |
| Mabie Consultancy Ltd | Wholesale & retail | 2023 |
| Mabwm Limited | Extraterritorial | 2009 |
| MAC Briscoe Limited | Transport & logistics | 2024 |
| MAC Mediation Ltd | Construction | 2016 |
| MAC-3K Int'L Limited | Wholesale & retail | 2024 |
| Mac-Moore Afro Limited | Wholesale & retail | 2025 |
| Macapparel Limited | Wholesale & retail | 2020 |
| Macaravans Limited | Transport & logistics | 2003 |
| Macenas Consultancy Ltd | Professional & scientific | 2019 |
| Macg Racing Limited | Professional & scientific | 2010 |
| Mach Systems Limited | Administrative & support | 2016 |
| Machethana Limited | Health & social care | 2018 |
| Machinery Well Ltd | Wholesale & retail | 2019 |
| Mackay Business Services Ltd | Administrative & support | 2021 |
| Mackervoy Properties Limited | Real estate | 2023 |
| Mackworth Business Services Limited | Hospitality | 1993 |
| Mackworth Estate Community Association Limited | Arts & recreation | 2009 |
| Mackworth News Express Ltd | Wholesale & retail | 2023 |
| Mackworth Pizza Limited | Hospitality | 2022 |
| Maclaine Asset Services Ltd | Real estate | 2020 |
| Macleodshield Ltd | Manufacturing | 2002 |
| Macmartin Limited | Professional & scientific | 2017 |
| Macoam Machinery Ltd | Financial services | 2015 |
| Macrofin International Ltd | Other services | 2022 |
| Macrofin Limited | Information & communication | 2018 |
| Macromole Ltd | Manufacturing | 2017 |
| Macs-Uk Limited | Real estate | 2023 |
| Macthor Limited | Real estate | 2025 |
| MAD Ange Entertainment Parties Limited | Arts & recreation | 2016 |
| MAD Gizmo Enterprises Limited | Information & communication | 2023 |
| MAD Hatters Findern Limited | Hospitality | 2023 |
| MAD Hot Fit Limited | Health & social care | 2021 |
| Madb Limited | Information & communication | 2014 |
| Madcat Software Ltd | Information & communication | 1999 |
| Maddock Holdings Limited | Financial services | 2023 |
| Made Living Ltd | Extraterritorial | 2020 |
| Made Sports Management Limited | Professional & scientific | 2021 |
| Madeline’S Beauty Room Ltd | Other services | 2021 |
| Maderich Limited | Information & communication | 1992 |
| Madhouse Property Investments Ltd | Real estate | 2024 |
| Madina Book Centre Ltd | Wholesale & retail | 2026 |
| Madube Enterprises Ltd | Health & social care | 2021 |
| MAE Investment Properties Limited | Real estate | 2025 |
| MAE Trading Limited | Wholesale & retail | 2011 |
| Maelor Dental Care Limited | Health & social care | 2012 |