| Madinah Property Ltd | Real estate | 2026 |
| Madison Rose Limited | Professional & scientific | 2017 |
| Madjjam Ltd | Real estate | 2015 |
| Madness Connection Ltd | Wholesale & retail | 2018 |
| Madura Private Limited | Wholesale & retail | 2014 |
| Maev Ltd | Wholesale & retail | 2023 |
| MAF Consulting Ltd | Information & communication | 2010 |
| Mafhh Limited | Construction | 2014 |
| MAG Capital Limited | Extraterritorial | 2012 |
| MAG London Ltd | Wholesale & retail | 2018 |
| Magat Holding Ltd | Manufacturing | 2025 |
| Magazine Heroes Limited | Administrative & support | 2015 |
| Magg Care Limited | Construction | 2017 |
| Magia Solutions Limited | Professional & scientific | 2004 |
| Magic Touch Healthcare Ltd | Administrative & support | 2023 |
| Magic Twin Ltd | Health & social care | 2015 |
| Magic Windows Innovation Ltd | Construction | 2018 |
| Magical Property Group Limited | Real estate | 2023 |
| Magicbeans Physical Audio Ltd | Information & communication | 2018 |
| Magnate Inc Limited | Professional & scientific | 2013 |
| Magnate Services Ltd | Professional & scientific | 2022 |
| Magnificent Property & Development Company Ltd | Real estate | 2023 |
| Magnum Drywall Solution Ltd | Construction | 2024 |
| Magnum Opus Knowledge Transfer Ltd | Real estate | 2006 |
| Magrathean UK Ltd. | Information & communication | 2026 |
| Magrinhos Garage Limited | Wholesale & retail | 2026 |
| Mahadeva Locum Limited | Health & social care | 2025 |
| Mahakali Limited | Real estate | 2018 |
| Mahakaya Ltd | Real estate | 2019 |
| Mahantam Ltd | Health & social care | 2023 |
| Maharaj Foods Limited | Wholesale & retail | 2013 |
| Maharaj Holdings Limited | Real estate | 2025 |
| Mahaveer Properties Limited | Real estate | 2019 |
| Mahavinayak Ltd | Real estate | 2020 |
| Mahavir Developers Ltd | Real estate | 2026 |
| Mahavir Trading Ltd | Transport & logistics | 2023 |
| Mahi Decorators Ltd | Construction | 2012 |
| Mahinay Care Limited | Health & social care | 2024 |
| Mahr Property UK Ltd | Real estate | 2022 |
| Mahraj Capital Limited | Financial services | 2025 |
| Mahrosh Ltd | Transport & logistics | 2018 |
| Maida Food Centre Ltd | Wholesale & retail | 2025 |
| Maiden Distribution Ltd | Wholesale & retail | 2024 |
| Maiden Property Ltd | Real estate | 2020 |
| Maidensgrove Limited | Real estate | 2005 |
| Maiky RUS Construction Ltd | Construction | 2025 |
| Main Source Technologies Ltd | Information & communication | 2013 |
| Main-Tec Property Services Ltd | Professional & scientific | 2013 |
| Maindola Consultancy Limited | Information & communication | 2017 |
| Mairo Limited | Professional & scientific | 2011 |
| Maisconstruct Ltd | Construction | 2021 |
| Maisie Timms Ltd | Professional & scientific | 2018 |
| Maison Malou Limited | Manufacturing | 2025 |
| Maitland Moore Limited | Professional & scientific | 2013 |
| Maitri Legal Consultancy Ltd | Professional & scientific | 2020 |
| Maitri Solution Limited | Information & communication | 2026 |
| Maitri Traders Ltd | Wholesale & retail | 2023 |
| Maiz Limited | Hospitality | 2025 |
| Maizymoo Limited | Information & communication | 2008 |
| Majada Ltd | Professional & scientific | 2011 |
| Majestic Gentlemen Limited | Other services | 2020 |
| Majestic Wine Warehouses Limited | Wholesale & retail | 1981 |
| Majesty Capital Limited | Professional & scientific | 2005 |
| Majik Consulting Limited | Professional & scientific | 2016 |
| Major.Music Entertainment Ltd | Information & communication | 2023 |
| MAK Estates Ltd | Real estate | 2023 |
| MAK Food Service Ltd | Hospitality | 2019 |
| Mak&Zak Ltd | Wholesale & retail | 2024 |
| Make FUN Happen Ltd | Construction | 2025 |
| Make Interiors (London) Limited | Arts & recreation | 2014 |
| Make Reality Ltd | Information & communication | 2020 |
| Maker Moving Pictures Ltd | Information & communication | 2020 |
| Makerfield Resources Limited | Professional & scientific | 2015 |
| Making Neoteric Homes Limited | Real estate | 2017 |
| Maknan Limited | Wholesale & retail | 2022 |
| Mako Construction Ltd | Construction | 2016 |
| Maksatics Limited | Arts & recreation | 2014 |
| Makuu Consultants Ltd | Financial services | 2017 |
| Malabliss Ltd | Construction | 2019 |
| Malachy Faulkner Fine Frames Limited | Manufacturing | 2017 |
| Malaczynski Burn Limited | Professional & scientific | 2005 |
| Malakiun Care Ltd | Health & social care | 2022 |
| Malcolm Grahame Consultants Limited | Professional & scientific | 2014 |
| Maldive Holidays Limited | Professional & scientific | 1987 |
| Malen Grassa LLP | | 2010 |
| Malengo Ltd | Real estate | 2020 |
| Malhotra and Associates Ltd | Administrative & support | 2019 |
| Malico Group Ltd | Wholesale & retail | 2017 |
| Malik Orthopaedic Surgery Ltd | Professional & scientific | 2011 |
| Malips Limited | Health & social care | 2024 |
| Mallow Property Services Limited | Construction | 2025 |
| Malo Electrician Ltd | Construction | 2024 |
| Malone Building Services Limited | Construction | 2015 |
| Malone Property Holdings Limited | Financial services | 2025 |
| Maltrealm Limited | Professional & scientific | 1996 |
| Malvern Close Management Company Limited | Extraterritorial | 1996 |
| Malvern Court (Harrow) RTM Company Limited | Households | 2011 |
| MAM Advisors Ltd | Professional & scientific | 2022 |
| Mama Bear Herbal Clinic Ltd | Health & social care | 2022 |
| Mama Cacao Collective CIC | Manufacturing | 2025 |