| M.W. Trustees Limited | Professional & scientific | 1991 |
| M.W.P. Contract Flooring Limited | Administrative & support | 1997 |
| M.Y Aesthetica Limited | Other services | 2022 |
| M.Y Global Trading Ltd | Wholesale & retail | 2022 |
| M.Yassin Ltd | Health & social care | 2022 |
| M.Z Essa Ltd | Health & social care | 2023 |
| M1 Consulting Limited | Information & communication | 2006 |
| M1 Hub Limited | Wholesale & retail | 2025 |
| M11BNA Limited | Households | 2022 |
| M2 Properties Limited | Construction | 2018 |
| M2 Recovery Holdings Ltd | Financial services | 2026 |
| M2 Recovery Ltd | Financial services | 2016 |
| M21 Studio Ltd | Manufacturing | 2025 |
| M27UK Ltd | Hospitality | 2020 |
| M2M Barber Ltd | Other services | 2025 |
| M2M Plumbing and Heating Ltd | Construction | 2023 |
| M2NR Ltd | Financial services | 2018 |
| M2SK Investments Limited | Real estate | 2022 |
| M2SQUARE Print and Retail Solutions Limited | Wholesale & retail | 2019 |
| M3 Alliance Ltd | Transport & logistics | 2025 |
| M3 Create Ltd | Manufacturing | 2016 |
| M3 Egbe Holding Ltd | Real estate | 2026 |
| M3 Financial Solutions Limited | Financial services | 2004 |
| M3R Group Ltd | Real estate | 2024 |
| M3R Holding Ltd | Financial services | 2025 |
| M4 Perfume Ltd | Wholesale & retail | 2025 |
| M76 Ltd | Administrative & support | 2022 |
| M7T3 Ltd | Professional & scientific | 2020 |
| M8 Pitstop Ltd | Manufacturing | 2017 |
| M9 Property Ltd | Real estate | 2023 |
| MA & ZA Consultancy Ltd | Professional & scientific | 2019 |
| MA Analysis Limited | Wholesale & retail | 2015 |
| MA Driving Academy Limited | Education | 2024 |
| MA Elite Trading Ltd | Wholesale & retail | 2025 |
| MA Infrastructure Limited | Professional & scientific | 2014 |
| MA International Ltd | Real estate | 2019 |
| MA Management Consulting Limited | Administrative & support | 2007 |
| MA Optix Ltd | Health & social care | 2024 |
| MA Packaging Limited | Wholesale & retail | 2024 |
| MA Properties Leics Ltd | Financial services | 2021 |
| MA Shop Design Ltd | Wholesale & retail | 2012 |
| MA Smiles Ltd | Health & social care | 2026 |
| MA Touch À MOI Limited | Wholesale & retail | 2022 |
| Ma&Me Limited | Wholesale & retail | 2019 |
| Ma&Pt Investments Limited | Real estate | 2019 |
| Ma's Cuisine Ltd | Hospitality | 2013 |
| Ma-Ba Kitchen Ltd | Hospitality | 2018 |
| MA11 Properties Limited | Real estate | 2016 |
| MAA Supermarket Ltd | Wholesale & retail | 2022 |
| MAA Vehicle Sales Ltd | Wholesale & retail | 2023 |
| Maahee's Way Limited | Manufacturing | 2023 |
| Maaheer Construction Ltd | Construction | 2025 |
| Maahi Food Limited | Hospitality | 2025 |
| Maahi Group Ltd | Financial services | 2024 |
| Maahi Transport Ltd | Transport & logistics | 2025 |
| Maan Couriers Ltd | Transport & logistics | 2018 |
| Maan Midlands Constructions Ltd | Construction | 2023 |
| Maan Solutions Limited | Administrative & support | 2015 |
| Maansi Investments Ltd | Real estate | 2025 |
| Maansi Ltd | Wholesale & retail | 2025 |
| Maar Consulting Ltd | Professional & scientific | 2019 |
| Maarfysolutions Ltd | Wholesale & retail | 2024 |
| Maariyah Properties Ltd | Real estate | 2016 |
| Maasho Limited | Hospitality | 2017 |
| MAB Shares Ltd | Administrative & support | 2012 |
| Mabel and EVE Ltd | Manufacturing | 2025 |
| Mabi Global Consulting Ltd | Professional & scientific | 2025 |
| MAC Associates (Leicester) Limited | Professional & scientific | 2007 |
| MAC FIN Client Services Limited | Financial services | 2013 |
| MAC FIN Consulting Limited | Financial services | 2011 |
| MAC FIN Finance Limited | Financial services | 2018 |
| MAC Health Transport Ltd | Transport & logistics | 2026 |
| MAC Lovin ST Martins Limited | Hospitality | 2021 |
| MAC Strategic Consultancy Limited | Professional & scientific | 2009 |
| Mac'Mannlee Ltd | Financial services | 2025 |
| MAC99 Catering & Events Limited | Health & social care | 2026 |
| Macaesthetic Leicester Ltd | Other services | 2022 |
| Macbeth 54 Limited | Professional & scientific | 2006 |
| Macc Cambs Limited | Other services | 2015 |
| Macc Fresh Ltd | Wholesale & retail | 2018 |
| Macc Property Investments Ltd | Real estate | 2024 |
| Macdave Services Ltd | Administrative & support | 2012 |
| Macdroid.Uk Limited | Other services | 2023 |
| Macgas Limited | Extraterritorial | 1954 |
| Machina Precision Limited | Manufacturing | 2015 |
| Machinewright Services Limited | Manufacturing | 2012 |
| Machining Technologies Ltd | Manufacturing | 2018 |
| Machiraju Services Ltd | Information & communication | 2024 |
| Maci Jayne & Co Ltd | Administrative & support | 2025 |
| Macintyre Clark LLP | | 2008 |
| Mack's Garage Limited | Wholesale & retail | 1980 |
| Mackenzies (Swindon) Limited | Hospitality | 2013 |
| Maclean Data Comms Limited | Information & communication | 1996 |
| Maclean Environmental Limited | Administrative & support | 2005 |
| Maclean Moore Limited | Administrative & support | 2012 |
| Macloving Ltd | Wholesale & retail | 2016 |
| Macmoon Limited | Wholesale & retail | 2026 |
| Macrae Consulting Services Ltd | Professional & scientific | 2025 |
| Macrofirm Limited | Information & communication | 2021 |
| Macs Electrical Limited | Construction | 1992 |