| Macdivine Healthcare Ltd | Health & social care | 2021 |
| Mach Speed Management Ltd | Professional & scientific | 2026 |
| Macphilips Foods Ltd. | Wholesale & retail | 2004 |
| Macturner Accounting Limited | Professional & scientific | 2004 |
| Macturner Care Limited | Administrative & support | 2006 |
| Macturner Estates Limited | Real estate | 2004 |
| Macturner Holdings Limited | Real estate | 2005 |
| Macturner Solutions Limited | Administrative & support | 2007 |
| Made by Three Ltd | Wholesale & retail | 2025 |
| Madeinthegym Ltd | Arts & recreation | 2026 |
| Madhav Trading Ltd | Wholesale & retail | 2023 |
| Madicare PPE Ltd | Administrative & support | 2026 |
| Madina Logistics Limited | Transport & logistics | 2026 |
| Maestro Beauty Ltd | Other services | 2021 |
| Maestronow Ltd | Wholesale & retail | 2024 |
| Maestrul Jarului Ltd | Hospitality | 2025 |
| Mag-Si Limited | Health & social care | 2021 |
| Magate Consultants Limited | Professional & scientific | 2019 |
| Magenta Divine Ltd | Professional & scientific | 2013 |
| Magic Decor Ltd | Construction | 2022 |
| Magic Hands Cleaners Ltd | Administrative & support | 2019 |
| Magic Hands Ventures Ltd | Administrative & support | 2024 |
| Magic to YOU Ltd | Arts & recreation | 2025 |
| Magicfingas Limited | Hospitality | 2025 |
| Magmaflow Engineering Ltd | Administrative & support | 2025 |
| Magmories Ltd | Manufacturing | 2025 |
| Magna Carta Accountancy Limited | Professional & scientific | 2016 |
| Magna Realty Ltd | Real estate | 2024 |
| Magnitunes Ltd | Information & communication | 2012 |
| Magnitunes Properties Ltd | Real estate | 2018 |
| Magnum Passive Fire Protection Ltd | Construction | 2023 |
| Magok UK Limited | Health & social care | 2014 |
| Magsyl Limited | Health & social care | 2021 |
| Mahal Property Investment Ltd | Real estate | 2024 |
| Mahal Property Ltd | Construction | 2022 |
| Mahdmo Ltd | Health & social care | 2014 |
| Mahon Enterprise Ltd | Wholesale & retail | 2026 |
| Mahtfix Ltd | Construction | 2025 |
| Maia Cleaning Services Limited | Administrative & support | 2025 |
| Maidie Create Limited | Education | 2012 |
| Mailan Solutions Ltd | Wholesale & retail | 2024 |
| Maintanex Ltd | Construction | 2018 |
| Maintenance X Limited | Construction | 2023 |
| Maison DE Finance Limited | Information & communication | 2026 |
| Maison D’Aura Ltd | Real estate | 2025 |
| Maison Novare Ltd | Wholesale & retail | 2022 |
| Majestic Autoworks Ltd | Wholesale & retail | 2025 |
| Majestics Properties Ltd | Real estate | 2024 |
| Major Parts Limited | Wholesale & retail | 2024 |
| Major Sandhu Construction Ltd | Construction | 2023 |
| Major Security London Ltd | Administrative & support | 2022 |
| Majortarget Limited | Information & communication | 2025 |
| Majs Resources Limited | Information & communication | 2015 |
| MAK Motor Services Limited | Wholesale & retail | 2019 |
| MAK Residentials Ltd | Real estate | 2021 |
| Makens Ventures Limited | Hospitality | 2020 |
| Maks Horizon Property Ltd | Real estate | 2024 |
| Maksal Limited | Construction | 2024 |
| Makz Garage Limited | Wholesale & retail | 2019 |
| Mala Fruit & VEG Ltd | Wholesale & retail | 2024 |
| Malam Suya HUT Limited | Wholesale & retail | 2023 |
| Maldi-Universe Ltd | Construction | 2017 |
| Malek Properties Ltd | Real estate | 2022 |
| Malhi Trade Group Ltd | Construction | 2026 |
| Malik E Solutions Limited | Wholesale & retail | 2021 |
| Maliks Group Ltd | Hospitality | 2022 |
| Malique & Co ENT Ltd | Wholesale & retail | 2025 |
| Mallett Group Ltd | Wholesale & retail | 2022 |
| Mallett Thermal Insulation Ltd | Construction | 2020 |
| MAM T Healthcare Services Limited | Health & social care | 2018 |
| MAM T'S Consultancy Ltd | Health & social care | 2009 |
| Mama Gina Ltd | Wholesale & retail | 2025 |
| Mama Sylvia's Ultimate Seasonings Ltd | Wholesale & retail | 2018 |
| Mamaruinge Enterprise Limited | Other services | 2018 |
| Mamasi Ltd | Hospitality | 2023 |
| Mamma Salsa Limited | Wholesale & retail | 2025 |
| MAN and Van Rubbish Removal Ltd | Water & waste | 2024 |
| Mandate Properties Limited | Real estate | 2022 |
| Mandhan Haulage Limited | Transport & logistics | 2026 |
| Mane & Co UK Ltd | Construction | 2025 |
| Manea Construction Ltd | Construction | 2022 |
| Manjinder SINGH2 Ltd | Construction | 2025 |
| Manjit Kaur Fresh Ltd | Wholesale & retail | 2025 |
| Manns Waste Management Limited | Water & waste | 2009 |
| Mannyfield Solution Ltd | Professional & scientific | 2014 |
| Mano Investments Limited | Real estate | 2024 |
| Manop Property Group Limited | Real estate | 2018 |
| Manor Fish Ltd | Hospitality | 2024 |
| Manpeh MAC London Business School Ltd | Education | 2021 |
| Manroop Logistics Services Ltd | Other services | 2026 |
| Mantej Ltd | Construction | 2017 |
| Manteon Services Ltd | Construction | 2014 |
| Mantrai Ltd | Information & communication | 2025 |
| Maple Trade Ltd | Wholesale & retail | 2023 |
| Mara Homes Property and Investments Limited | Hospitality | 2024 |
| Maramureseanca Limited | Wholesale & retail | 2019 |
| Maramureseanul Ltd | Wholesale & retail | 2017 |
| Marashi & Co Limited | Transport & logistics | 2015 |
| Marble Flaws Ltd | Other services | 2025 |
| Marbut Limited | Construction | 2015 |