| M & M Access Limited | Manufacturing | 2003 |
| M & N Consulting Ltd | Professional & scientific | 2022 |
| M & T Wakefield Properties Limited | Real estate | 2001 |
| M and B Local Ltd | Wholesale & retail | 2021 |
| M and H Roofing Solutions Limited | Administrative & support | 2015 |
| M B Tree Surgery Limited | Administrative & support | 2015 |
| M C M Alarms Ltd | Administrative & support | 2009 |
| M Capital Holdings Ltd | Financial services | 2025 |
| M D Protap Ltd | Hospitality | 2022 |
| M J Burns Limited | Information & communication | 2011 |
| M J Painter and Decorator Limited | Construction | 2026 |
| M J Wearn Financial Services Limited | Financial services | 2017 |
| M Mcgowan Limited | Construction | 2011 |
| M Projects London Ltd | Construction | 2020 |
| M Young Landscaping Limited | Administrative & support | 2022 |
| M&A Air Conditioning Limited | Construction | 2010 |
| M&H GEE Enterprise Limited | Hospitality | 2024 |
| M&M Family Investments Ltd | Real estate | 2020 |
| M. Coleman Bricklaying and Construction Ltd | Construction | 2018 |
| M.Camara Support Limited | Professional & scientific | 2016 |
| M.D. & P. Plumbing & Heating Limited | Construction | 2002 |
| M.J.D Groundworks Ltd | Construction | 2025 |
| M.J.L. Construct Limited | Construction | 2023 |
| M.Mellamphy Ltd | Health & social care | 2026 |
| M.O. Motors Ltd | Wholesale & retail | 2019 |
| M.P.M. Windows & Doors Solution Ltd | Construction | 2022 |
| M.S Building Services Limited | Extraterritorial | 1993 |
| M.S.O Builders Limited | Construction | 2023 |
| M2MB Limited | Financial services | 2025 |
| MAB Commercial Contracts Limited | Other services | 2018 |
| Mabbutt Limited | Real estate | 2023 |
| MAC Automotive Solutions Ltd | Wholesale & retail | 2025 |
| MAC PCN Ltd | Manufacturing | 2015 |
| Macintyre Cabinetry Ltd | Manufacturing | 2023 |
| MAD Tekkerz Limited | Wholesale & retail | 2022 |
| Madpconsulting Ltd | Information & communication | 2015 |
| Madux Ltd | Professional & scientific | 2024 |
| Maffy-Max Ltd | Transport & logistics | 2026 |
| Magenta Direct Ltd | Other services | 2017 |
| Magic Chef Irchester Ltd | Hospitality | 2018 |
| Magma Construction Ltd | Construction | 2022 |
| Magnabuild Ltd | Construction | 2016 |
| Magneto 1212 Ltd | Transport & logistics | 2015 |
| Magnolious Care Ltd | Health & social care | 2021 |
| Magpie Draughting Limited | Administrative & support | 2003 |
| Mahavir Foods Ltd | Manufacturing | 2015 |
| Mainstream Consulting Management Limited | Professional & scientific | 2012 |
| Maison Cordell Limited | Wholesale & retail | 2025 |
| Majestic Swimming School Ltd | Education | 2022 |
| MAK Dog Handler Ltd | Administrative & support | 2020 |
| Makro Holding Limited | Administrative & support | 2001 |
| Makro Properties Limited | Real estate | 1976 |
| Makro Self Service Wholesalers Limited | Wholesale & retail | 1970 |
| Maksrec Ltd | Wholesale & retail | 2019 |
| Malaby Biogas Limited | Energy | 2009 |
| Malcolm Thomas Computer Solutions Limited | Information & communication | 2003 |
| Malone Barber Co Ltd | Other services | 2024 |
| Maltavini Limited | Hospitality | 2005 |
| MAM & PB Ltd | Transport & logistics | 2016 |
| MAM Machinery Ltd | Manufacturing | 2023 |
| Mamaflow Ltd | Arts & recreation | 2025 |
| Mamaia Minimarket Ltd | Wholesale & retail | 2025 |
| Mambo Munchies Ltd | Hospitality | 2024 |
| Mammoth Moments Ltd | Wholesale & retail | 2025 |
| Mamtora Consulting Ltd | Financial services | 2013 |
| MAN in Black Media Ltd | Information & communication | 2006 |
| Mane Consulting Limited | Information & communication | 2026 |
| Maniek Cars Limited | Manufacturing | 2015 |
| Manju Property Solutions Ltd | Real estate | 2021 |
| Mannyyz Limited | Construction | 2023 |
| Manor Croft Business Solutions Ltd | Professional & scientific | 2026 |
| Manucommunitie C.I.C. | Professional & scientific | 2025 |
| Manver Driving Services Ltd | Transport & logistics | 2016 |
| Manzil Prints Ltd | Wholesale & retail | 2025 |
| Mapak Consultancy Ltd | Administrative & support | 2019 |
| Mapleline Solutions Ltd | Information & communication | 2016 |
| Marcus Wakefield Properties Limited | Households | 2019 |
| Maree Wine Ltd | Wholesale & retail | 2025 |
| Mares Engineering Ltd | Professional & scientific | 2024 |
| Margomat Ltd | Transport & logistics | 2017 |
| Marian Courier Express Limited | Transport & logistics | 2025 |
| Marina Kallo Ltd | Wholesale & retail | 2025 |
| Marine Distribution Ltd | Wholesale & retail | 2020 |
| Marini Consulting Limited | Professional & scientific | 2026 |
| Mark Access UK Limited | Wholesale & retail | 2011 |
| Mark Barber Associates Ltd | Education | 2019 |
| Mark Driver Ltd | Transport & logistics | 2016 |
| Mark Laxton Engineering Limited | Professional & scientific | 2011 |
| Mark Warren Textiles Limited | Wholesale & retail | 2013 |
| Mark Wilkinson Investments II Limited | Professional & scientific | 2003 |
| Mark Wilkinson Investments Limited | Agriculture & fishing | 2003 |
| Market Research Practice Ltd | Professional & scientific | 2023 |
| Markowski Service Ltd | Wholesale & retail | 2017 |
| Marler Haley Limited | Manufacturing | 2009 |
| Marmon Group Limited(The) | Other services | 1978 |
| Marques Electrical Ltd | Energy | 2012 |
| Marriotts Multi-Trade Limited | Construction | 2020 |
| Marshall Middleton Cross Limited | Real estate | 2010 |
| Marshall's Mobile Mechanics Ltd | Wholesale & retail | 2022 |
| Marshfield Rentals Ltd | Real estate | 2022 |