| Mashie & Guttie Consulting Limited | Professional & scientific | 2025 |
| Mason & SON Roofing Company Limited | Construction | 2022 |
| Masons Fire and Security Ltd | Construction | 2026 |
| Masr Building Solutions Ltd | Construction | 2024 |
| Massala Club Ltd | Hospitality | 2021 |
| Massey's Skip Hire Ltd | Water & waste | 2025 |
| MAT Kowalczyk Ltd | Professional & scientific | 2017 |
| Matched Medtech Ltd | Wholesale & retail | 2024 |
| Mather Emotional Wellbeing Ltd | Health & social care | 2013 |
| Matrix Projects 24 Limited | Professional & scientific | 2026 |
| Matt Leete Photography Limited | Professional & scientific | 2018 |
| Matt Stait Electrical Limited | Energy | 2018 |
| Matthew Bond Enterprises Limited | Agriculture & fishing | 2011 |
| Matthews Brickwork Limited | Construction | 2003 |
| Matthi.Ist Ltd | Transport & logistics | 2025 |
| Mavimi Ltd | Professional & scientific | 2020 |
| Mavira Limited | Information & communication | 2024 |
| Maxx Enterprises Limited | Administrative & support | 2006 |
| Maxx Property Group Ltd | Real estate | 2019 |
| Maybank Holdings Limited | Professional & scientific | 2002 |
| Maybank TRS Ltd | Administrative & support | 2013 |
| Mayburyelectrical Ltd | Construction | 2024 |
| Mayfair Business Specialists Ltd | Professional & scientific | 2020 |
| Mayur Homes Ltd | Real estate | 2024 |
| MB Intermediary Limited | Professional & scientific | 2025 |
| MB Services (Tamworth) Limited | Construction | 2011 |
| Mbbw Holdings Ltd | Administrative & support | 2023 |
| MBM Construction Limited | Construction | 2018 |
| MBS Business Partnership Limited | Health & social care | 2012 |
| MBS Logistics 2016 Limited | Transport & logistics | 2016 |
| MC 161926 Limited | Hospitality | 2021 |
| MC Kickboxing & Fitness Limited | Arts & recreation | 2018 |
| MC Property Matanice Ltd | Construction | 2023 |
| Mcafee Autocare Ltd | Wholesale & retail | 2025 |
| Mccool Co Limited | Financial services | 2016 |
| MCD Developments (Tamworth) Ltd | Construction | 2021 |
| Mckay Investments Limited | Professional & scientific | 2021 |
| Mckeefry Irish Music Festival Limited | Arts & recreation | 2013 |
| Mckenzie Manufacturing Services Ltd | Manufacturing | 2011 |
| Mclaughlin & Murphy Solutions Ltd | Professional & scientific | 2024 |
| Mclellan Holdings Limited | Other services | 2020 |
| MCM Recruitment Solutions Limited | Administrative & support | 2026 |
| MCP Accounting Ltd | Professional & scientific | 2024 |
| MD Ideal Trans Ltd | Transport & logistics | 2018 |
| MD Legal Consulting Services Limited | Professional & scientific | 2026 |
| MD Smith Consultants Ltd | Professional & scientific | 2015 |
| Mddw Trading Limited | Wholesale & retail | 2025 |
| MDL Plumbing & GAS Services Ltd | Construction | 2009 |
| ME Myself and Mind Limited | Information & communication | 2018 |
| Mear Interiors and Landscapes Ltd | Construction | 2018 |
| Measured (QS Services) Limited | Professional & scientific | 2013 |
| MED Estenity Ltd | Health & social care | 2021 |
| Meddiccii Limited | Construction | 2008 |
| Medi - Immune Limited | Professional & scientific | 2002 |
| Medical Personnel UK Limited | Health & social care | 2024 |
| Medico Legal Expertise Limited | Professional & scientific | 2022 |
| Medico-Legal & Neuroscience Partnership Limited | Professional & scientific | 2016 |
| Medics Financial Services Limited | Financial services | 1983 |
| Medline Consultancy Limited | Professional & scientific | 2018 |
| Meefong Food Ltd | Hospitality | 2025 |
| Megga Group Holdings Ltd | Financial services | 2024 |
| Megga Properties Limited | Real estate | 2022 |
| MEI Analytics Ltd | Information & communication | 2022 |
| Melbourne Medical Writing Limited | Other services | 2015 |
| Meldor Limited | Other services | 2015 |
| Menbros Links Limited | Wholesale & retail | 2019 |
| Mercia Blinds Ltd | Construction | 2022 |
| Mercia Boxing Club CIC | Education | 2022 |
| Mercia Cleaning Services Ltd | Administrative & support | 2022 |
| Mercia Engineering Limited | Professional & scientific | 2013 |
| Mercia Fire and Security Ltd | Administrative & support | 2023 |
| Mercia Holdings Group Ltd | Financial services | 2022 |
| Mercia Laser Limited | Manufacturing | 2022 |
| Mercia Marketing Limited | Professional & scientific | 2025 |
| Mercia Marquee Events Limited | Administrative & support | 2011 |
| Mercia Primary Academy Trust | Education | 2013 |
| Mercia Pumps Ltd | Construction | 2020 |
| Mercia Semiconductor Limited | Other services | 2019 |
| Mercia Site Services Ltd | Construction | 2019 |
| Mercia Supply Chain Limited | Wholesale & retail | 2019 |
| Mercia Utility Services Limited | Administrative & support | 2019 |
| Mercian Charcoal CIC | Administrative & support | 2024 |
| Mercian Compliance Ltd | Professional & scientific | 2026 |
| Mercian Construction Solutions Limited | Professional & scientific | 2025 |
| Mercian Corporate Events Limited | Other services | 2024 |
| Mercian Energy Limited | Professional & scientific | 2023 |
| Mercian Installations Limited | Construction | 2022 |
| Mercian Law Limited | Professional & scientific | 2009 |
| Mercian Management Consultancy Ltd | Professional & scientific | 2018 |
| Mercian Medical Ltd | Professional & scientific | 2018 |
| Mercian Toolmaking Co. (Tamworth) Limited | Manufacturing | 1973 |
| Mere Green Electrical Limited | Construction | 2003 |
| Meridian Cctv Limited | Administrative & support | 2005 |
| Meridian Security Installations Ltd | Administrative & support | 2014 |
| Merit Accounting Limited | Professional & scientific | 2020 |
| Merlin Motor Company Midlands Limited | Wholesale & retail | 2021 |
| Merlin Tech Ltd | Construction | 2012 |
| Metalyte Limited | Extraterritorial | 2006 |
| Metalyte Pipeworks Ltd | Extraterritorial | 2012 |
| Meuk Property Limited | Real estate | 2018 |