| Maufhh Transport Ltd | Transport & logistics | 2021 |
| Mauka Property Company Limited | Real estate | 2025 |
| Mauli Property Services Limited | Real estate | 2017 |
| Mava Recruitment Limited | Administrative & support | 2013 |
| Mavanhomes Limited | Real estate | 2020 |
| Maven Industrial Technologies Ltd | Professional & scientific | 2020 |
| Mavenprotech Ltd | Information & communication | 2026 |
| Maverick Care Ltd | Administrative & support | 2020 |
| Mavers Properties Ltd | Construction | 2024 |
| Mawa Traders Ltd | Wholesale & retail | 2025 |
| Mawans Collections Ltd | Wholesale & retail | 2020 |
| MAX Cabs Ltd | Transport & logistics | 2026 |
| MAX Car Parts Slough Ltd | Wholesale & retail | 2024 |
| Maxaura Limited | Professional & scientific | 1991 |
| Maxell Europe Limited | Wholesale & retail | 1980 |
| Maxim Traders Limited | Wholesale & retail | 2025 |
| Maxima Services Limited | Other services | 2024 |
| Maxine Support Ltd | Public administration | 2023 |
| Maxn Group Ltd | Wholesale & retail | 2025 |
| Maxsimai Limited | Information & communication | 2025 |
| Maxwell Management Solutions Limited | Administrative & support | 2025 |
| MAY Books Limited | Information & communication | 2020 |
| May's Chocolate House CIC | Wholesale & retail | 2024 |
| May-Day Services Ltd | Administrative & support | 2024 |
| Maya Cricket Club Ltd | Education | 2025 |
| Maya Events Limited | Hospitality | 2023 |
| Maya Investment Property Limited | Real estate | 2024 |
| Maya Supported Living Limited | Health & social care | 2018 |
| Mayank's Elite Limited | Professional & scientific | 2021 |
| Mayar Luxe Ltd | Wholesale & retail | 2025 |
| Mayertorne Ltd | Professional & scientific | 2020 |
| Mayfair Bloom Limited | Households | 2024 |
| Mayfair Business Investments (UK) Ltd | Wholesale & retail | 2012 |
| Mayfair Design & Construction Ltd | Construction | 2018 |
| Mayfair Property Estates Limited | Households | 1996 |
| Mayflower Care Home (Northfleet) Limited | Health & social care | 2002 |
| Mayflower Nominee Co 1 Limited | Extraterritorial | 2015 |
| Mayflower Nominee Co 2 Limited | Extraterritorial | 2015 |
| Mayflower Way Capital Ltd | Financial services | 2024 |
| Maylance Properties Limited | Real estate | 2025 |
| Mayling Builders Ltd | Construction | 2012 |
| Mayset Limited | Real estate | 1985 |
| MAZ Argan Ltd | Manufacturing | 2022 |
| MAZ Management Ltd | Transport & logistics | 2020 |
| MAZ Software Ltd | Information & communication | 2025 |
| Mazara Properties Limited | Real estate | 2019 |
| Mazz Services Ltd | Transport & logistics | 2022 |
| Mazzz Estates Ltd | Households | 2021 |
| MB HGV Ltd | Transport & logistics | 2023 |
| MB Houses Ltd | Real estate | 2024 |
| MB Personal Training Ltd | Arts & recreation | 2013 |
| MB Property Services and Management Limited | Real estate | 2026 |
| MB Real Estate Services Ltd | Financial services | 2023 |
| Mbassa Limited | Transport & logistics | 2008 |
| MBC 2012 Limited | Administrative & support | 2010 |
| MBC Electrical Ltd | Construction | 2023 |
| MBD Professional Services Limited | Professional & scientific | 2025 |
| MBE Installation Services Limited | Construction | 2003 |
| MBM Consultations Limited | Professional & scientific | 2019 |
| MBM Property Services Ltd | Administrative & support | 2025 |
| MBM Tuition Ltd | Education | 2024 |
| Mbnr Property Flips Limited | Real estate | 2026 |
| Mbnr Property Ltd | Financial services | 2026 |
| MBR Collection PVT Ltd | Wholesale & retail | 2025 |
| MBR Foods Ltd | Wholesale & retail | 2022 |
| MBR International Ltd | Wholesale & retail | 2019 |
| MBR OIL &GAS Group Ltd | Administrative & support | 2018 |
| MBS Asset Management UK Limited | Professional & scientific | 2024 |
| MBS Equipment U.K., Ltd | Financial services | 2020 |
| MBS Lighting UK Limited | Administrative & support | 2014 |
| MBX Properties Ltd | Real estate | 2026 |
| MC Gourmet Group Ltd | Hospitality | 2026 |
| MC Property Lettings Ltd | Households | 2020 |
| MC UK Services Ltd | Construction | 2021 |
| MCA Transport Ltd | Transport & logistics | 2018 |
| Mcabra Group Ltd | Financial services | 2024 |
| Mcauley Interiors Limited | Construction | 2017 |
| Mcbill Limited | Administrative & support | 2018 |
| Mcbrics Investments Ltd | Manufacturing | 2024 |
| Mcdowell Civil Engineering Surveying Limited | Professional & scientific | 2018 |
| MCF Install Ltd | Manufacturing | 2026 |
| Mcfar Group Ltd | Transport & logistics | 2024 |
| Mcgrove Newco 2 Limited | Other services | 2025 |
| Mcgrove Newco Limited | Other services | 2025 |
| MCH Customs Limited | Transport & logistics | 2020 |
| Mckenzie Care Homes Ltd | Financial services | 2007 |
| Mckenzie Care Ltd | Health & social care | 2012 |
| Mclay Consulting Limited | Information & communication | 2018 |
| MCM ENG. UK Limited | Construction | 2025 |
| Mcmircea & Co Ltd | Transport & logistics | 2018 |
| MCN Associates Limited | Professional & scientific | 2009 |
| Mcosmetic Limited | Wholesale & retail | 2026 |
| Mcqueen's Academy Limited | Education | 2017 |
| Mcram Ltd | Water & waste | 2025 |
| Mcram Propco Ltd | Administrative & support | 2025 |
| Mcwhites Services Ltd | Construction | 2023 |
| MD & K Properties Ltd | Real estate | 2017 |
| MD Barber Slough Ltd | Other services | 2025 |
| MD Electricals (London) Ltd | Manufacturing | 2023 |
| MD Interiorsuk Limited | Construction | 2022 |