| M S Frenchies UK Ltd | Agriculture & fishing | 2022 |
| M Woollett Electrical Limited | Manufacturing | 2017 |
| M&C Property Ventures Ltd | Construction | 2026 |
| M&E Project Services Ltd | Construction | 2022 |
| M. Bailey Tree Services Limited | Agriculture & fishing | 2016 |
| M.C.S. Estates Ltd | Financial services | 2023 |
| M.G Boatfitters Ltd | Construction | 2012 |
| M.I.S Products Limited | Wholesale & retail | 2003 |
| M.J.K. Fitter Ltd | Construction | 2025 |
| M.W. Cripwell Limited | Construction | 1975 |
| MA & M Property Limited | Real estate | 2021 |
| MAC Beauty Ltd | Health & social care | 2016 |
| MAC Building Experts Limited | Construction | 2025 |
| Macky's Heating Ltd | Construction | 2016 |
| MAD Letts Ltd | Real estate | 2022 |
| Made by MOM Limited | Wholesale & retail | 2025 |
| Magic Concept Ltd | Construction | 2023 |
| Magic Makeovers Ltd | Construction | 2025 |
| Magic Rose Transport Ltd | Transport & logistics | 2017 |
| Magiclean (Midlands) Ltd | Administrative & support | 2021 |
| Magmix Engineering Limited | Other services | 2005 |
| Magpol Ltd | Wholesale & retail | 2017 |
| Mahad Uzair Ltd | Wholesale & retail | 2024 |
| Mahi Property and Investments Ltd | Real estate | 2025 |
| Maja UK Trans Ltd | Transport & logistics | 2016 |
| Major Farming Limited | Agriculture & fishing | 2014 |
| MAK 4X4 Motors Ltd | Wholesale & retail | 2024 |
| MAK Furniture Ltd | Wholesale & retail | 2021 |
| Make IT Happen London Limited | Professional & scientific | 2014 |
| Making Trails Ltd | Arts & recreation | 2023 |
| Malik Brothers Travel Limited | Administrative & support | 2026 |
| Malone Group GB Limited | Professional & scientific | 2012 |
| Maltfront Limited | Real estate | 1989 |
| Management Certification Services Limited | Professional & scientific | 2014 |
| Manavis Management Limited | Households | 2022 |
| Mandy Lines Limited | Professional & scientific | 2019 |
| Mango Twist Manchester Ltd | Hospitality | 2026 |
| Manor Electrical Services Limited | Manufacturing | 2009 |
| Manor Joinery Limited | Construction | 2024 |
| Manor Property Company (Burton) Limited | Real estate | 1974 |
| Manor UK Holdings Limited | Real estate | 2025 |
| Manorfield Properties Ltd | Real estate | 2004 |
| Manorfields (Alrewas) Management Company Limited | Households | 1998 |
| Manrol Ltd | Professional & scientific | 2024 |
| Manton Associates Limited | Professional & scientific | 2019 |
| Mapent Ltd | Professional & scientific | 2013 |
| Mapent Property Ltd | Real estate | 2026 |
| Maple (233) Limited | Households | 2004 |
| Maple Lodge Burton Ltd | Health & social care | 2023 |
| Maple Properties (Midlands) Limited | Real estate | 2007 |
| Maplevale Holdings Limited | Professional & scientific | 2024 |
| Maplevale Limited | Construction | 2021 |
| MAR Speed Trans Ltd | Transport & logistics | 2023 |
| Marcy Transport Ltd | Wholesale & retail | 2025 |
| Marfleet Facilities Ltd | Construction | 2016 |
| Margin AI Limited | Professional & scientific | 2025 |
| Marie Bauer Ltd | Agriculture & fishing | 2023 |
| Marine and Power Engineering Limited | Manufacturing | 2025 |
| Mariod Ltd | Wholesale & retail | 2025 |
| Mariusz Zera Ltd | Transport & logistics | 2018 |
| Mark Adamson Construction ( M.A.C ) Limited | Construction | 2011 |
| Mark Allen (Midlands) Limited | Wholesale & retail | 2017 |
| Mark Nelson Solutions Ltd | Construction | 2012 |
| Mark Taylor Plumbing & Heating Ltd | Construction | 2011 |
| Mark Willday Light Haulage Ltd. | Transport & logistics | 2003 |
| Mark Your Moment Events Ltd | Professional & scientific | 2026 |
| Mark-Leonard Unltd | Extraterritorial | 2023 |
| Mark.A.Johnson Limited | Manufacturing | 2012 |
| Markd Limited | Information & communication | 2024 |
| Market Place Travel Ltd | Administrative & support | 2018 |
| Market Street Mortgages Limited | Financial services | 2000 |
| Markham's Horse Transport Ltd | Transport & logistics | 2023 |
| Markier Trans Ltd | Transport & logistics | 2014 |
| Marley Group Limited | Financial services | 2021 |
| Marley Limited | Manufacturing | 2018 |
| Marlin Spares Ltd | Wholesale & retail | 2024 |
| Marlix Capital Limited | Financial services | 2020 |
| Marlix Developments Ltd | Construction | 2020 |
| Marmo Floor Designs Ltd | Construction | 2025 |
| Mars Data Installations Limited | Extraterritorial | 2016 |
| Marshall Mahoney Ltd | Information & communication | 2011 |
| Marvel Transport Limited | Transport & logistics | 2022 |
| Masai Motor Works Ltd | Wholesale & retail | 2024 |
| Masala Tutbury Ltd | Hospitality | 2024 |
| Mash Inns Limited | Real estate | 2016 |
| Mason Consultants Limited | Professional & scientific | 2008 |
| Mason James Appointments (UK) Limited | Administrative & support | 2014 |
| Masons of Wharfedale Limited | Real estate | 2010 |
| Masw Limited | Hospitality | 2014 |
| Mater Domus Hospitality Ltd | Hospitality | 2025 |
| Matrix Safety Training Ltd | Education | 2020 |
| Matrix Supply Chain Consultancy Ltd | Professional & scientific | 2021 |
| Matsuri Nails Ltd | Other services | 2025 |
| Matthew Peake Plumbing Limited | Construction | 2011 |
| Matthew Prince Ltd | Wholesale & retail | 2003 |
| Matuntelu Spedition Ltd | Transport & logistics | 2019 |
| Maverick Bidco Limited | Financial services | 2017 |
| Maverick Coatings Ltd | Construction | 2022 |
| Maverick Holdco Limited | Financial services | 2017 |
| Maverick Interco Limited | Financial services | 2017 |