| M.M.C.C. Contracting Ltd | Administrative & support | 2008 |
| M.O.M. Estates Limited | Real estate | 2016 |
| M.P. Business Associates Limited | Information & communication | 2000 |
| M.R. Design & Engineering Ltd | Administrative & support | 2023 |
| M.T. Realty Ltd | Construction | 2022 |
| M.W. Construction Cheshire Ltd | Construction | 2023 |
| M10 Architects Limited | Professional & scientific | 2020 |
| M2 Risk Advisory Limited | Public administration | 2019 |
| M20 Personal Training Limited | Arts & recreation | 2016 |
| M4 Testing Ltd | Information & communication | 2022 |
| M56 Junction 10 Storage Ltd | Transport & logistics | 2019 |
| M9 Project Solutions Limited | Professional & scientific | 2026 |
| M9 Solutions Ltd | Health & social care | 2018 |
| MA Blythe Property Group Ltd | Real estate | 2024 |
| MA Consultants Bramhall Ltd | Administrative & support | 2016 |
| MA Envirotech Group Ltd | Financial services | 2026 |
| MA Lettings North West Ltd | Real estate | 2026 |
| MA Management Solutions Limited | Administrative & support | 2015 |
| MA Perfect Store Ltd | Wholesale & retail | 2024 |
| MA Wride Consulting Ltd | Information & communication | 2018 |
| Ma&Hw Ltd | Construction | 2024 |
| Ma's Homes Limited | Real estate | 2003 |
| Maase Consulting Limited | Administrative & support | 2024 |
| MAB Express Ltd | Transport & logistics | 2025 |
| Mabelmae Limited | Professional & scientific | 2022 |
| Mabon Ledger Ltd | Professional & scientific | 2024 |
| MAC Commercial Holdings Limited | Real estate | 2026 |
| MAC Dental Ltd | Health & social care | 2019 |
| MAC Geotechnics Ltd | Administrative & support | 2015 |
| MAC Move Ltd | Transport & logistics | 2021 |
| MAC Surveyors Ltd | Other services | 2024 |
| Mac&Tosh Limited | Professional & scientific | 2017 |
| Mac-Gaver Ltd | Transport & logistics | 2018 |
| MAC22 Consulting Ltd | Professional & scientific | 2017 |
| Macarthur Energy Solutions Limited | Administrative & support | 2013 |
| Maccalin Associates Limited | Administrative & support | 2014 |
| Macdowall Power Services Limited | Administrative & support | 2012 |
| Maceash Engineering Ltd | Information & communication | 2025 |
| Macfarlane IT Services Ltd | Information & communication | 2023 |
| Mach Resources UK Ltd | Water & waste | 2023 |
| Mack Access Solutions Limited | Information & communication | 2019 |
| Mackay Draughting & Design Limited | Professional & scientific | 2011 |
| Mackay Safety Services Limited | Administrative & support | 2014 |
| Mackenzie Corporate Limited | Information & communication | 2017 |
| Maclawson Family Holdings Ltd | Financial services | 2025 |
| Maclean GAS and Heating Limited | Other services | 2017 |
| Maclean Medical Limited | Health & social care | 2022 |
| Macleod Software Solutions Ltd | Information & communication | 2016 |
| Macphail Associates Limited | Administrative & support | 2015 |
| Macval Ltd | Administrative & support | 2007 |
| MAD Lets Limited | Real estate | 2019 |
| Madana Travels Limited | Administrative & support | 2025 |
| Madarvets Limited | Professional & scientific | 2022 |
| Madden UK Properties Limited | Real estate | 2021 |
| Maddockcommunications Ltd | Information & communication | 2024 |
| Maddy Long Lashes Ltd | Other services | 2020 |
| Made by Them Limited | Wholesale & retail | 2023 |
| Made to Brand Limited | Wholesale & retail | 2025 |
| Madej Cargo Limited | Transport & logistics | 2018 |
| Madex Project Management Services Ltd | Transport & logistics | 2023 |
| Madhouse Engineering Limited | Administrative & support | 2013 |
| Madhuram Foods PVT Limited | Wholesale & retail | 2026 |
| Madison Gardens Garage Company Limited | Real estate | 2005 |
| MAE Springs Ltd | Hospitality | 2024 |
| Maelberi Consultancy Ltd | Professional & scientific | 2023 |
| Magbhars Limited | Health & social care | 2014 |
| Magcarr Limited | Administrative & support | 2022 |
| Magda's House Ltd | Real estate | 2024 |
| Magetractor Limited | Information & communication | 2018 |
| Maghy's Ltd | Manufacturing | 2019 |
| Magic Magis Car Detailing Ltd | Administrative & support | 2026 |
| Magic Nick Surface Repairs Ltd | Construction | 2020 |
| Magic Roofing Cheshire Ltd | Construction | 2022 |
| Magic Roofing Warrington Ltd | Construction | 2021 |
| Magic Stays Limited | Real estate | 2024 |
| Magician Business Ltd | Administrative & support | 2015 |
| Magic’S Properties Ltd | Real estate | 2026 |
| Magipo Ltd | Other services | 2019 |
| Magland Consulting Limited | Administrative & support | 2025 |
| Magmal Limited | Information & communication | 1998 |
| Magna Motor Group Ltd | Wholesale & retail | 2020 |
| Magnabi Limited | Information & communication | 2017 |
| Magne Consulting Limited | Information & communication | 2012 |
| Magnifyb Limited | Administrative & support | 2021 |
| Magnolia Bell Limited | Hospitality | 2009 |
| Magnox Electric Group Pension Trustee Company Limited | Professional & scientific | 2000 |
| Magpie Software Solutions Limited | Information & communication | 2018 |
| Magsar 14 Limited | Real estate | 2014 |
| Maguire Land Co Limited | Real estate | 2022 |
| Mahari Investments Ltd | Real estate | 2019 |
| Maharry Engineering Limited | Professional & scientific | 2017 |
| Mahaveer Limited | Administrative & support | 2016 |
| Mahavir Consultants Limited | Administrative & support | 2009 |
| Mahi Consulting Limited | Professional & scientific | 2018 |
| Mahmoud Investments Limited | Real estate | 2023 |
| MAI BOR Construction Consulting Limited | Professional & scientific | 2022 |
| MAI Life Ltd | Wholesale & retail | 2021 |
| Maia Consulting Limited | Information & communication | 2016 |
| Mailee Ltd | Transport & logistics | 2015 |
| Main Street Procurement Ltd | Professional & scientific | 2026 |