| Mark Management Ltd | Health & social care | 2026 |
| Mark Mayhew Physiotherapy Ltd | Health & social care | 2024 |
| Mark Noblet Education Limited | Education | 2016 |
| Mark Riley (Academy) Limited | Other services | 2010 |
| Mark Traynor Consultancies Ltd | Professional & scientific | 2009 |
| Market Basket HFD Ltd | Wholesale & retail | 2025 |
| Market Medic Ltd | Health & social care | 2023 |
| Market Mover Ltd | Wholesale & retail | 2026 |
| Market My Property Ltd | Hospitality | 2023 |
| Market Pricing Holdings Limited | Financial services | 2025 |
| Markkickss Ltd | Wholesale & retail | 2024 |
| Marlagh Limited | Professional & scientific | 2018 |
| Marling & Evans Limited | Manufacturing | 2008 |
| Marlow Industries Ltd | Manufacturing | 2025 |
| Maroch Healthcare Limited | Wholesale & retail | 1993 |
| Marry Carry Investments Limited | Real estate | 2012 |
| Marry Carry LLP | | 2012 |
| Marrying Meals Ltd | Hospitality | 2025 |
| Mars Engineering Services Ltd | Administrative & support | 2026 |
| Marsden and Slaithwaite Transition Towns | Education | 2010 |
| Marsden Community Trust Limited | Other services | 2015 |
| Marsden Community Trust Trading Limited | Wholesale & retail | 2017 |
| Marsden Fisheries Limited | Hospitality | 2025 |
| Marsden Jazz Festival Limited | Arts & recreation | 2001 |
| Marsden Kids Club Community Interest Company | Health & social care | 2013 |
| Marsden Village Website Project CIC | Information & communication | 2026 |
| Marsh Court Management Company Limited | Households | 1997 |
| Marsh Curry House Ltd | Hospitality | 2025 |
| Marsh DIY Limited | Wholesale & retail | 2013 |
| Marsh Foot Centre Ltd | Health & social care | 2019 |
| Marsh Lush Ltd | Other services | 2025 |
| Marsh Medical Skin Clinic Ltd | Other services | 2018 |
| Marsh Nails Ltd | Other services | 2024 |
| Marsh Tailors Limited | Manufacturing | 2023 |
| Marsh United Bowling Club Limited(The) | Hospitality | 1903 |
| Marshall Management Developments Ltd | Construction | 2024 |
| Marsof Property Ltd | Real estate | 2022 |
| Marstons Chicken Shop Limited | Hospitality | 2011 |
| Martek Composites Limited | Manufacturing | 1998 |
| Martial Cadwallader Limited | | 1919 |
| Martin Grimes Technology Solutions Limited | Construction | 2006 |
| Martin Mellor Services Limited | Real estate | 2019 |
| Martin Pearson Limited | Financial services | 2005 |
| Martin Sec.Com Limited | Professional & scientific | 2016 |
| Martin Sons & Company Limited | Extraterritorial | 2008 |
| Martora Properties Ltd | Real estate | 2024 |
| Martyn Sales Financial Planning Limited | Financial services | 2025 |
| Marvelous Europe Limited | Information & communication | 2012 |
| Marvin House Residential Care Ltd | Health & social care | 2026 |
| Marwa Medical Ltd | Health & social care | 2026 |
| Maryam Medical Services Ltd | Health & social care | 2023 |
| Marysvale Consulting Limited | Other services | 2024 |
| MAS Management Services Ltd | Construction | 2007 |
| MAS Properties Group Ltd | Construction | 2024 |
| Masag Security Limited | Administrative & support | 2021 |
| Masah Ltd | Wholesale & retail | 2023 |
| Masala Spice Lindley Ltd | Hospitality | 2025 |
| Masarat Global Ltd | Administrative & support | 2022 |
| Masharib Global Services Ltd | Wholesale & retail | 2025 |
| Mashsoft Limited | Other services | 1997 |
| Masoom Care Ltd | Health & social care | 2020 |
| Masoom Care Welfare Ltd | Health & social care | 2025 |
| Massey Productions Ltd | Information & communication | 2010 |
| Mast Dash Cams Ltd | Wholesale & retail | 2019 |
| Masters DC Marsh Ltd | Administrative & support | 2025 |
| MAT Baker Construction Ltd | Construction | 2026 |
| Match Healthcare Ltd | Administrative & support | 2022 |
| Matchdaytix Limited | Wholesale & retail | 2026 |
| Matchextra Limited | Real estate | 2002 |
| Matchtime Munchers Ltd | Manufacturing | 2026 |
| Matema Ltd | Health & social care | 2025 |
| Mather Excel Limited | Professional & scientific | 2008 |
| Matiyah Properties Limited | Real estate | 2022 |
| Mato Fire and Security Ltd | Administrative & support | 2024 |
| Matrix Mount Wise (GP) Limited | Financial services | 2010 |
| Matrix Mount Wise Limited Partnership | | 2010 |
| Matrix Podiatry Limited | Financial services | 2018 |
| Matson Carter Limited | Manufacturing | 2020 |
| Mattbzh Consulting Limited | Information & communication | 2011 |
| Maughans TOO Ltd | Hospitality | 2020 |
| Maverick VSB Limited | Financial services | 2016 |
| Maverick Wires Limited | Manufacturing | 2003 |
| Mavi Constructions Limited | Construction | 2024 |
| Mavis Asset Management Ltd | Real estate | 2025 |
| Mavs Hudd Ltd | Hospitality | 2026 |
| MAX Emmerson Productions Ltd | Arts & recreation | 2014 |
| Max-Wellbeing Ltd | Health & social care | 2017 |
| Maxed OUT Mechanics Ltd | Wholesale & retail | 2026 |
| Maxi Van Hire Ltd | Administrative & support | 2025 |
| Maxiellis Ltd | Information & communication | 2026 |
| Maxis Balti & Pizza Bar Ltd | Hospitality | 2017 |
| Maxwell Jewelry & Home Decorations PTL Ltd | Manufacturing | 2023 |
| Max’S FIX Estates Limited | Households | 2023 |
| Maya Butchers Ltd | Wholesale & retail | 2025 |
| Maychart Limited | Professional & scientific | 1985 |
| Mayfair Sports Limited | Health & social care | 2019 |
| Maylen Elevator Services Ltd | Professional & scientific | 2017 |
| Maypole Inn (Warley) Ltd | Hospitality | 2021 |
| Mays Butchers & Groceries Limited | Hospitality | 2022 |
| Mays Community Project CIC | Hospitality | 2026 |