| Marion Homes Limited | Construction | 2002 |
| Mark Bowen Painters and Decorators Ltd | Construction | 2014 |
| Marketglen Limited | Hospitality | 1985 |
| Marley Driver Hire Ltd | Transport & logistics | 2021 |
| Marston Consultancy Limited | Professional & scientific | 2025 |
| Martin & Jones Marketing Limited | Professional & scientific | 2024 |
| Martin Evans Building Limited | Construction | 2015 |
| Martin Evans Contracting Ltd | Agriculture & fishing | 2015 |
| Martin Evans Farming Ltd | Agriculture & fishing | 2015 |
| Martin Evans Poultry Ltd | Manufacturing | 2017 |
| Martin Jones Financial Services Limited | Financial services | 2016 |
| Martyn R Kent FCA CTA Ltd | Professional & scientific | 2013 |
| Mary Walker Exhibitions Limited | Extraterritorial | 2013 |
| Mathswatch Limited | Information & communication | 2022 |
| Matt Owen Electrical Services Ltd | Construction | 2018 |
| Matthew Kemp Municipal Services Ltd | Wholesale & retail | 2011 |
| Maven Telecommunications Limited | Information & communication | 2022 |
| Maximus Contracting Limited | Construction | 2026 |
| May-Hem Fabric Ltd | Wholesale & retail | 2020 |
| MBO Safety Services Limited | Administrative & support | 2008 |
| Mcallister Consultancy Services Limited | Health & social care | 2023 |
| Mccourt Stables Limited | Agriculture & fishing | 2022 |
| Mcdonald Automotive Limited | Wholesale & retail | 2001 |
| Mcevoy Foods International Limited | Wholesale & retail | 1995 |
| MD Construction & Windows Ltd | Construction | 2025 |
| MD Warriors Ltd | Arts & recreation | 2012 |
| MDP Shropshire Limited | Construction | 2017 |
| Meandering Wood Limited | Manufacturing | 2017 |
| Meat Masters Limited | Hospitality | 2003 |
| MED Equus Limited | Professional & scientific | 2010 |
| Medaid Services (Sales) Ltd | Information & communication | 2017 |
| Medlar Press Limited | Information & communication | 1994 |
| Meijuan Limited | Hospitality | 2026 |
| Melangell Limited | Manufacturing | 2024 |
| Melya & Co. Trading Ltd. | Wholesale & retail | 2015 |
| Merch Rocks Limited | Wholesale & retail | 2017 |
| Merevalley Limited | Construction | 2003 |
| MHV Solutions Ltd | Construction | 2019 |
| Midac UK Ltd | Wholesale & retail | 2012 |
| Middleton Barn Developments Limited | Real estate | 2005 |
| Midland Automotive Holdings Limited | Financial services | 1994 |
| Midland Automotive Parts Limited | Wholesale & retail | 1978 |
| Miethaus Limited | Real estate | 2025 |
| Mile END Business Park Ltd | Real estate | 2021 |
| Mill Farm Eggs Ltd | Agriculture & fishing | 2015 |
| Mill Housing Limited | Real estate | 2025 |
| Millie's Cafe @ Llangedwyn Ltd | Hospitality | 2025 |
| Milo Development 2 Ltd | Construction | 2025 |
| Minshall Place (Oswestry) Limited | Hospitality | 2011 |
| Mist-Air Dust Suppression Limited | Manufacturing | 1975 |
| Mist-Air Environmental Systems Limited | Extraterritorial | 1999 |
| MJC Wilson Ltd | Health & social care | 2007 |
| MJS Blackshaw Holdings Limited | Financial services | 2019 |
| MKH Agriculture Limited | Financial services | 2022 |
| MKH Portfolio Limited | Real estate | 2015 |
| MMJ Holdings Limited | Real estate | 2021 |
| MML Estates Ltd | Real estate | 2024 |
| MML Tyre Repairs Ltd | Wholesale & retail | 2017 |
| Moch Daear Ltd | Construction | 2025 |
| Model Car Competitions Ltd | Wholesale & retail | 2023 |
| Modular Adaptation Pods (Group) Ltd | Administrative & support | 2017 |
| Modular Wrap Co Ltd | Professional & scientific | 2025 |
| Mogo Property Limited | Construction | 2021 |
| Mojo 2 Limited | Real estate | 2018 |
| Momentum Wines Limited | Wholesale & retail | 2005 |
| Montgomery Canal Reconstruction Limited | Construction | 2018 |
| Montgomery Waterway Restoration Trust(The) | Other services | 1980 |
| Moon Pixels Ltd | Information & communication | 2022 |
| Morcup Trading Ltd | Wholesale & retail | 2026 |
| More Kolors Limited | Administrative & support | 2019 |
| Moreton Hall Education Limited | Education | 2022 |
| Morgan Enterprise Group Ltd | Financial services | 2023 |
| Morgan Fire & Security Systems Limited | Administrative & support | 2011 |
| Morgans Plumbing & Heating Ltd | Construction | 2012 |
| Morgans Plumbing & Heating Topco Ltd | Financial services | 2024 |
| Morgans Plumbing and Heating Holdings Ltd | Construction | 2024 |
| Morris Holdings (U.K.) Limited | Administrative & support | 2004 |
| Morris Transport | Transport & logistics | 2006 |
| Morris Transport UK Limited | Extraterritorial | 2002 |
| Morton Consultants Limited | Professional & scientific | 2003 |
| Morton Growers Limited | Agriculture & fishing | 2012 |
| Moto Tracktech Ltd | Wholesale & retail | 2025 |
| Mount Pleasant Amenity Company Limited | Construction | 2025 |
| Mountain Challenge Events Limited | Arts & recreation | 2012 |
| Mozillion Group Limited | Wholesale & retail | 2025 |
| MR Tubby Limited | Wholesale & retail | 2006 |
| MS Holiday Cotts Ltd | Hospitality | 2026 |
| Msmk Holdings Ltd | Real estate | 2018 |
| MT Haulage Contractors Ltd | Transport & logistics | 2025 |
| Mucksucker Ltd | Manufacturing | 2022 |
| MULTIGRUP2025 Limited | Transport & logistics | 2025 |
| Murray Agriculture Limited | Agriculture & fishing | 2022 |
| Mutt Designs Ltd | Wholesale & retail | 2020 |
| My Moto Maps Ltd | Information & communication | 2026 |
| My Yardspace Limited | Other services | 2016 |
| Mymaximus College UK Ltd | Education | 2026 |
| N a Commercials Limited | Wholesale & retail | 2008 |
| N Hemsley & Sons Contracting Limited | Transport & logistics | 2014 |
| Nabma Limited | Other services | 2017 |
| Naive Creative Studio Limited | Professional & scientific | 2023 |