| M4U Holdings Ltd | Financial services | 2024 |
| MA Consultant Services Ltd | Professional & scientific | 2025 |
| MAA Krupa Ltd | Hospitality | 2019 |
| Maaya Limited | Wholesale & retail | 2017 |
| MAB Building Limited | Construction | 2016 |
| Maba Management Ltd | Real estate | 2021 |
| Maclean Recruitment and Cleaning Services Limited | Administrative & support | 2009 |
| Macs Energy Ltd | Construction | 2011 |
| Macs Estates Ltd | Real estate | 2021 |
| Madan Maini Properties Ltd | Real estate | 2018 |
| Maddox Capital Ltd | Real estate | 2023 |
| Maddox Developments Limited | Real estate | 2026 |
| Madhavi Logistics Ltd | Transport & logistics | 2024 |
| MAE Consultancy Services Ltd | Health & social care | 2022 |
| Mafer M & E by Design Ltd | Construction | 2018 |
| Mage Construction Ltd | Construction | 2026 |
| Magic House Sourcing Ltd | Real estate | 2020 |
| Magicwave Solutions Ltd | Information & communication | 2010 |
| Magnate Hamm Ltd | Financial services | 2025 |
| Magnate Hammersmith Ltd | Financial services | 2025 |
| Magnate SB Limited | Financial services | 2021 |
| Magnifico U.K. Limited | Wholesale & retail | 2000 |
| Magnit Ltd | Hospitality | 2014 |
| Magnussen Orthopaedics Ltd | Health & social care | 2024 |
| Mahalaxmi Catering Limited | Hospitality | 2016 |
| Mahnettot and Rupstoh Investments Ltd | Financial services | 2023 |
| Mahogany House (Newtown) Limited | Health & social care | 2014 |
| Mainsail Investments Limited | Financial services | 2020 |
| Mainsail Ltd | Administrative & support | 2015 |
| Maison Estate Agent (UK) Limited | Real estate | 2021 |
| Maison Kitchens Limited | Construction | 2024 |
| Maitreydave Limited | Information & communication | 2014 |
| Majestic Junction Company Ltd | Other services | 2024 |
| Majestic Perfection Company Limited | Other services | 2025 |
| Majestic Three Line UK Ltd | Wholesale & retail | 2021 |
| Major KIY Ltd | Information & communication | 2022 |
| Makk Homes Limited | Construction | 2023 |
| Makool Ltd | Manufacturing | 2026 |
| Malana Homes Ltd | Real estate | 2025 |
| Malde Health Solutions Ltd | Health & social care | 2017 |
| Malde Property Ltd | Real estate | 2019 |
| Malikadam Ltd | Real estate | 2012 |
| Malix Pictures Ltd | Information & communication | 2023 |
| Mallampati Consulting Limited | Information & communication | 2014 |
| Malone Hair Ltd | Other services | 2020 |
| Malvern 96 Limited | Real estate | 2019 |
| Malwa Holdings Limited | Financial services | 2026 |
| Mama Ibti Ltd | Manufacturing | 2024 |
| MAN HCW Limited | Other services | 2021 |
| Manageable Maths Limited | Education | 2024 |
| Manana Tree Limited | Real estate | 2025 |
| Manichem Limited | Wholesale & retail | 2007 |
| Manifest Your Magic Ltd | Construction | 2024 |
| Manj Clark Yordanov Finance and Accountancy Services Ltd | Professional & scientific | 2012 |
| Manoj Services Limited | Information & communication | 2023 |
| Manor Burger Web Ltd | Wholesale & retail | 2024 |
| Manor LEE Properties Limited | Construction | 2025 |
| Mansar Consulting Limited | Administrative & support | 2014 |
| Mansons Chemists Limited | Wholesale & retail | 1984 |
| Manticore AW Limited | Professional & scientific | 2014 |
| Mantix Consulting Limited | Wholesale & retail | 2018 |
| Manuel Courier Limited | Transport & logistics | 2019 |
| Manuel Oak Ltd | Real estate | 2022 |
| Manvarco Ltd | Wholesale & retail | 2020 |
| Manvarco Property Ltd | Real estate | 2025 |
| Many Hands Global Ltd | Hospitality | 2015 |
| Maomre Limited | Hospitality | 2024 |
| Maple Leaf Estates Limited | Real estate | 2002 |
| Maps Project and Contract Management Ltd | Professional & scientific | 2024 |
| Mapson Limited | Wholesale & retail | 2009 |
| Mara Properties Limited | Real estate | 2020 |
| Marathon Education Limited | Education | 2023 |
| Marble Stone Restorations Ltd | Administrative & support | 2011 |
| Marc Abraham Consulting Ltd | Information & communication | 2009 |
| Marc Mylum Limited | Financial services | 2011 |
| Marigold Sunshine Properties Limited | Real estate | 2023 |
| Mario Mastic Silicon Applicator Ltd | Construction | 2020 |
| Mark & MAX Ltd | Professional & scientific | 2017 |
| Mark Kinsella Productions Ltd | Information & communication | 2013 |
| Mark Manning Consulting Limited | Real estate | 2020 |
| Mark Zudini Architecture + Design Limited | Professional & scientific | 2017 |
| Marketsimple Limited | Other services | 1992 |
| Markev Advisory Ltd | Professional & scientific | 2025 |
| Marko Righo Ltd | Professional & scientific | 2022 |
| Marks Jacobson (London) Limited | Extraterritorial | 1994 |
| Marlin Standard Associates Limited | Administrative & support | 2014 |
| Marnel Group Ltd | Financial services | 2025 |
| Marnel Homes Ltd | Construction | 2025 |
| Marnel Project Holly Ltd | Construction | 2025 |
| Maroli Design Group Ltd | Professional & scientific | 2015 |
| Marrew Limited | Wholesale & retail | 2025 |
| Mars Devtech Limited | Real estate | 2025 |
| Mars EYE Ltd | Education | 2024 |
| Marsh Point Freehold Limited | Real estate | 2012 |
| Marston Associates (London) Limited | Real estate | 2004 |
| Marvel Roofing Ltd | Construction | 2021 |
| Marvmove Limited | Construction | 2023 |
| MAS CB Ltd | Hospitality | 2023 |
| Mascot Auto Co Limited | Construction | 2020 |
| Master Accounting Solutions Ltd | Professional & scientific | 2016 |