| Mark Crossley Ltd | Transport & logistics | 2012 |
| Mark J Hartley Engineering Ltd | Professional & scientific | 2026 |
| Mark Mcdonald Consultancy Limited | Wholesale & retail | 2014 |
| Mark Salmon (Plasterers) Limited | Manufacturing | 2003 |
| Mark Sugden Joinery and Building Ltd | Construction | 2012 |
| Marlyn Engineering Ltd. | Manufacturing | 1999 |
| Marmion Shoe Repairs Limited | Other services | 2013 |
| Marquis Masonry (NW) Ltd | Construction | 2026 |
| Marquismasonry Ltd | Construction | 2025 |
| Marshalls Motor Company Limited | Wholesale & retail | 2020 |
| Martyn Anderson Ltd | Transport & logistics | 2024 |
| Marwa & Fatima Limited | Transport & logistics | 2024 |
| MAS+ Ltd | Professional & scientific | 2026 |
| Massey Medical Services Ltd | Health & social care | 2026 |
| Master KUT Nelson Ltd | Other services | 2025 |
| Mastercraft Rugs Holdings Limited | Financial services | 2021 |
| Mastercraft Rugs Limited | Wholesale & retail | 1982 |
| Match Media Ltd | Professional & scientific | 2021 |
| Matka Restaurant Limited | Hospitality | 2026 |
| Matt Cook Electrical Services Ltd | Construction | 2015 |
| MAX Business Ltd | Hospitality | 2015 |
| MAX Phones Limited | Wholesale & retail | 2022 |
| Maxalan Homes Limited | Real estate | 2010 |
| MAY Baguion Ltd | Wholesale & retail | 2025 |
| Mayer Groundworks Limited | Construction | 2018 |
| Mayfair Construction Ltd | Real estate | 2015 |
| Mayfair Developments (MCR) Ltd | Real estate | 2012 |
| Mayfair Developments (NW) Limited | Real estate | 2017 |
| Mayfair Industrial 1ST Limited | Real estate | 2018 |
| Mayor Design Ltd | Professional & scientific | 2026 |
| MB Nova Ltd | Wholesale & retail | 2025 |
| MBA (Brierfield) Limited | Professional & scientific | 2010 |
| MBA Corp Limited | Real estate | 2018 |
| MBA Supplements Ltd | Wholesale & retail | 2024 |
| Mbanj Traders Ltd | Wholesale & retail | 2025 |
| Mcfly & Tannen Property Investments Ltd | Water & waste | 2024 |
| Mcidelivery Ltd | Transport & logistics | 2025 |
| MD IT Consulting Limited | Information & communication | 2025 |
| Meade Property Holdings Ltd | Financial services | 2024 |
| Medical Expert-Ease Ltd | Professional & scientific | 2015 |
| Medical Solutions NW Limited | Health & social care | 2019 |
| Medico Assist Limited | Other services | 2016 |
| Medilink Care Limited | Administrative & support | 2024 |
| Medilynq Limited | Health & social care | 2022 |
| Medina Housing Ltd | Real estate | 2021 |
| Medina Poultry Products Ltd | Wholesale & retail | 2019 |
| Medina Property Portfolio Ltd | Real estate | 2024 |
| Mediterranean Uruci Construction Ltd | Construction | 2023 |
| Meem Couture Ltd | Wholesale & retail | 2026 |
| MEG Systems Limited | Information & communication | 1996 |
| Megamarkt Ltd | Wholesale & retail | 2022 |
| Megamax Marketing UK Limited | Wholesale & retail | 2012 |
| Mehdipharma Limited | Health & social care | 2024 |
| Meridian Northwest Limited | Wholesale & retail | 2019 |
| Merrylegs Marketing Limited | Professional & scientific | 2024 |
| Merseyside Buildings Preservation Trust | Health & social care | 1988 |
| Metro Cabs Doncaster Limited | Transport & logistics | 2025 |
| Metro Properties (NW) Ltd | Real estate | 2018 |
| Metroautosolutions Ltd | Wholesale & retail | 2026 |
| MEX Performance Solutions Ltd | Professional & scientific | 2026 |
| MFR Studios Ltd | Information & communication | 2023 |
| MGR Management Limited | Construction | 2019 |
| MH Car Seat Covers Limited | Wholesale & retail | 2024 |
| MI Consult Limited | Administrative & support | 2015 |
| MIA Construction Northwest Ltd | Construction | 2025 |
| MIA Property Services Limited | Households | 2021 |
| Mian G Fruit & VEG Ltd | Wholesale & retail | 2026 |
| Mian Investments Limited | Real estate | 2025 |
| Michael Bolton & Sons Limited | Administrative & support | 2002 |
| Michael Gaut Consulting Limited | Information & communication | 2005 |
| Michael James Furniture Limited | Manufacturing | 2009 |
| Michael’S Brothers Limited | Construction | 2019 |
| MIL Trading & Investments Ltd | Real estate | 2025 |
| Mill Town Pies Ltd | Manufacturing | 2018 |
| Millbank (Darwen) Management Company Limited | Extraterritorial | 2023 |
| Millercare Holdings Limited | Financial services | 2024 |
| Millercare Limited | Wholesale & retail | 1993 |
| Millfields Motor Services Limited | Wholesale & retail | 2013 |
| Mindful Pathway Support Limited | Education | 2025 |
| Mindplan Productions Ltd | Information & communication | 2014 |
| Mini Magical Minds Ltd | Wholesale & retail | 2025 |
| Minto Housing Limited | Real estate | 2025 |
| Minute Convenience Store Ltd | Wholesale & retail | 2022 |
| Miranda Graphics Ltd | Information & communication | 2015 |
| MIS Building Subcontractors Ltd | Construction | 2021 |
| Mkiz Wholesale Clothing Ltd | Wholesale & retail | 2019 |
| Mkiz Wrapping Limited | Manufacturing | 2019 |
| ML Blinds Ltd | Administrative & support | 2017 |
| MLD Engineering Limited | Manufacturing | 1994 |
| MLD Enterprises Holdings Limited | Financial services | 2026 |
| MLD Enterprises Limited | Manufacturing | 2005 |
| MM and Sons Limited | Wholesale & retail | 2025 |
| MMA Phones Ltd | Wholesale & retail | 2021 |
| MMS Rentals Limited | Real estate | 2023 |
| MN Cars Ltd | Wholesale & retail | 2020 |
| Mnako Ltd | Manufacturing | 2024 |
| MNI Tech Ltd | Information & communication | 2026 |
| MNM Ltd | Wholesale & retail | 2026 |
| MO Barbers Ltd | Other services | 2025 |
| Mobiles Doctor Ltd | Wholesale & retail | 2023 |