| Market Square (Wolverhampton) Properties Ltd | Real estate | 2023 |
| Marley Mo's Limited | Administrative & support | 2012 |
| Marlow & Mills Holdings Ltd | Financial services | 2026 |
| Marlow Mills Signature Homes Ltd | Real estate | 2026 |
| Marmaris Figo Barber Ltd | Other services | 2021 |
| Martello Fiche Limited | Professional & scientific | 2007 |
| Martyn Price (Bolts & Nuts) Limited | Wholesale & retail | 1972 |
| Martyn Price Holdings Limited | Wholesale & retail | 2018 |
| Mary Hendry Consulting Limited | Professional & scientific | 2014 |
| Mary House Guest House Ltd | Hospitality | 2017 |
| Mary Mahoney Consulting Limited | Professional & scientific | 2022 |
| Marykenny Limited | Other services | 2024 |
| Masac Group Ltd | Financial services | 2024 |
| Masefield Epson Ltd | Extraterritorial | 2012 |
| Masefield-Beta Ltd | Manufacturing | 1961 |
| Masoma Apparel Ltd | Manufacturing | 2026 |
| Mastclimber Consultants Ltd | Professional & scientific | 2009 |
| Mastclimbers R US Ltd | Professional & scientific | 2009 |
| Master Drains Ltd | Water & waste | 2021 |
| Master Garden Nutrients Limited | Manufacturing | 2020 |
| MAT2U 1 Ltd | Real estate | 2024 |
| MAT2U Ltd | Real estate | 2026 |
| Mata Leao BJJ Ltd | Wholesale & retail | 2021 |
| Match Power Industry Limited | Arts & recreation | 2015 |
| Matita Trans Ltd | Transport & logistics | 2025 |
| Mattsons Beds UK Ltd | Wholesale & retail | 2022 |
| Maverick Holdings and Investments Ltd | Financial services | 2026 |
| Maverick Mother Holdings Ltd | Financial services | 2025 |
| Maverick Mother Ltd | Information & communication | 2025 |
| Maverick Mutts Swimming Ltd | Other services | 2024 |
| Maverick Sport Ltd | Education | 2021 |
| Maverick Swimming Solutions Ltd | Education | 2022 |
| MAX Entertainment Limited | Arts & recreation | 2024 |
| MAX G Studio Ltd | Construction | 2025 |
| Maximilian Services Limited | Health & social care | 2015 |
| Maxtime Hr/Payroll Limited | Information & communication | 2022 |
| Maxtime Limited | Information & communication | 2005 |
| Maxwell Ventures Limited | Construction | 2014 |
| Mayberry Pharma SUB 1 Limited | Extraterritorial | 2025 |
| Mayberry Pharma SUB 2 Limited | Extraterritorial | 2025 |
| Mayberry Pharma SUB 3 Limited | Extraterritorial | 2025 |
| Mayfair Square Limited | Extraterritorial | 2013 |
| Mayfield H C Limited | Administrative & support | 2018 |
| Mayflower Canton Limited | Hospitality | 2025 |
| Maynetech Limited | Construction | 1998 |
| Mayteguk Ltd | Real estate | 2020 |
| Maziikuku Ltd | Manufacturing | 2024 |
| Mazziria Ltd | Wholesale & retail | 2025 |
| MB Franchise Board Limited | Transport & logistics | 2022 |
| Mbbn Holdings Limited | Financial services | 2022 |
| Mbereko Investments Ltd | Public administration | 2019 |
| MBY Limited | Construction | 2002 |
| MC Precision Limited | Administrative & support | 2002 |
| Mccalla Properties Limited | Real estate | 2025 |
| MCD Investment Group Limited | Real estate | 2026 |
| Mcdonald Diecasting Limited | Manufacturing | 1979 |
| Mcdougalls Maintenance Ltd | Manufacturing | 1984 |
| Mcnulty Mechanical Services Ltd | Manufacturing | 2024 |
| MCS Aesthetics Wholesale Limited | Wholesale & retail | 2023 |
| MD Care Holdings Limited | Health & social care | 2024 |
| MD Construction Site Services Limited | Professional & scientific | 2013 |
| MD Goodman Ltd | Administrative & support | 2022 |
| MDA PM Holdings Ltd | Financial services | 2019 |
| MDA Project Management Services Limited | Professional & scientific | 2009 |
| MDB Couriers Ltd | Transport & logistics | 2011 |
| ME Time Stories Ltd | Information & communication | 2025 |
| Meadow Barn Day Nursery & Preschool Ltd | Health & social care | 2025 |
| Meadow Green Homes Holdings Limited | Real estate | 2021 |
| Meadow Green Homes Limited | Real estate | 2021 |
| Medbury Health & Wellness Ltd | Health & social care | 2022 |
| Medical Acme Research Solutions Ltd | Professional & scientific | 2025 |
| Medical Services UK Ltd | Health & social care | 2023 |
| Mediedify Global Ltd | Education | 2026 |
| Mediskin Ltd. | Other services | 2004 |
| Medlow Holdings & Investments Ltd | Financial services | 2024 |
| Mehmiprestigemotors Ltd | Wholesale & retail | 2022 |
| Mehran Spares Ltd | Wholesale & retail | 2024 |
| Mehran Wrap Fortints Ltd | Wholesale & retail | 2025 |
| Melectro Electrical Services Limited | Manufacturing | 2020 |
| Melia Accounting Limited | Professional & scientific | 2019 |
| Melliwoire Ltd | Administrative & support | 2023 |
| Mellowheart Ltd | Health & social care | 2019 |
| Meltingblossom Ltd | Wholesale & retail | 2019 |
| Melton Estates Limited | Real estate | 2012 |
| Menfit Property Ltd | Real estate | 2024 |
| Mercez Ltd | Financial services | 2023 |
| Mercia Architectural Limited | Manufacturing | 2002 |
| Mercia Consultants Ltd | Professional & scientific | 2000 |
| Mercia Group Holdings Limited | Professional & scientific | 1978 |
| Mercia Surveyors Limited | Professional & scientific | 2024 |
| Mercian Preservation Limited | Construction | 1971 |
| Mereside Care Home Ltd | Administrative & support | 2017 |
| Mereside Holdings Ltd | Administrative & support | 2017 |
| Meridian Steel Limited | Manufacturing | 2019 |
| Merlin Blue Property Services Ltd | Real estate | 2024 |
| Merlin Holdings Limited | Professional & scientific | 2007 |
| Merry Hill Motors Ltd | Wholesale & retail | 2018 |
| Merryhill Auto Centre Midlands Ltd | Wholesale & retail | 2015 |
| MET Professional Ltd | Administrative & support | 2026 |
| MET Recruitment Holdings Ltd | Financial services | 2022 |