| Mayfair London Property Limited | Real estate | 2022 |
| Mayfair Way Ltd | Professional & scientific | 2013 |
| Mayfairtrends LP | | 2019 |
| Mayin Properties Ltd | Real estate | 2021 |
| Mayon Entertainment Limited | Information & communication | 2020 |
| Maypel Limited | Financial services | 2021 |
| Mayter Ltd | Real estate | 2021 |
| Mayu Imports and Exports Limited | Hospitality | 2025 |
| Mayur Builder Ltd | Construction | 2025 |
| Maz's Auto Ltd | Wholesale & retail | 2018 |
| MB Developments (London) Ltd | Real estate | 2015 |
| MB General Construction Limited | Construction | 2016 |
| MB Kitchen Ltd | Hospitality | 2026 |
| MBD Services Ltd | Other services | 2018 |
| Mbla Greenview Ltd | Health & social care | 2019 |
| MBP Plumbing Limited | Construction | 2020 |
| MBP Services Ltd | Hospitality | 2025 |
| MBR Chinese Ltd | Hospitality | 2026 |
| MBW Enterprise Ltd | Administrative & support | 2020 |
| MC Diamonds Limited | Manufacturing | 2001 |
| Mc's Health & Beauty Ltd | Wholesale & retail | 2022 |
| MCA LAI Services Ltd | Administrative & support | 2023 |
| Mccann Global Services Limited | Wholesale & retail | 2004 |
| Mccarthy Property Investments Ltd | Financial services | 2017 |
| MCD Render Limited | Construction | 2021 |
| MCE Civils and Groundworks Limited | Construction | 1963 |
| Mces Limited | Real estate | 1995 |
| Mcfar & Co Ltd | Professional & scientific | 2024 |
| Mcgee (Haulage) Limited | Construction | 1990 |
| Mcgee (Polo Land) Limited | Administrative & support | 2004 |
| Mcgee Bedrock Limited | Water & waste | 2008 |
| Mcgee Environmental Services Limited | Construction | 1964 |
| Mcgee Group (Holdings) Limited | Construction | 1968 |
| Mcgee Group Limited | Construction | 1979 |
| Mcgee Trustee Limited | Administrative & support | 2020 |
| Mckarthy Labs Limited | Information & communication | 2018 |
| Mcloughlin Carpentry Services Ltd | Construction | 2017 |
| MCP Decorators Ltd | Construction | 2008 |
| MD Builders and Decorators Ltd | Construction | 2011 |
| MD Coaching Team Ltd | Health & social care | 2023 |
| MD Realty Ventures Ltd | Real estate | 2025 |
| MD Right Investment Ltd | Financial services | 2024 |
| MD UK Enterprise Ltd | Wholesale & retail | 2025 |
| Mdaar Ltd | Information & communication | 2024 |
| MDB London Ltd. | Construction | 2019 |
| MDC Decorator Ltd | Construction | 2013 |
| Mderissyconsultancy Ltd | Information & communication | 2025 |
| Mdhventures Ltd | Arts & recreation | 2025 |
| MDM Management Ltd | Wholesale & retail | 2019 |
| Mdmor Limited | Hospitality | 2018 |
| MDR Cleaning Services Ltd. | Administrative & support | 2006 |
| MDT Ventures Ltd | Real estate | 2022 |
| ME and the Crew Limited | Other services | 2007 |
| MEA Associates Ltd | Construction | 2019 |
| Meadow Walk Dental Ltd | Health & social care | 2022 |
| Meadowjoy Ltd | Wholesale & retail | 2026 |
| Meal Box Express Limited | Hospitality | 2020 |
| Measured Services (London) Ltd | Professional & scientific | 2026 |
| Meat Lords Limited | Manufacturing | 2016 |
| Meatfellas Ltd | Wholesale & retail | 2024 |
| Meatpulse Limited | Wholesale & retail | 2025 |
| MEC Southern Ltd | Administrative & support | 2008 |
| Mech Solutions Group Ltd | Construction | 2025 |
| Mechanical Vent Ltd | Construction | 2021 |
| Mechanicscroll Ltd | Information & communication | 2026 |
| Mecomp International | | 1989 |
| MED X Drug Limited | Wholesale & retail | 2016 |
| Medallion Arena Ltd | Wholesale & retail | 2025 |
| Medcolegal Ltd | Health & social care | 2024 |
| Meddent JO Ltd | Health & social care | 2022 |
| Medi Crew Ltd | Wholesale & retail | 2012 |
| Media Transportation Ltd | Transport & logistics | 2015 |
| Mediacraft Creatives Ltd | Wholesale & retail | 2017 |
| Medical Crescent Ltd | Health & social care | 2009 |
| Medical Equipment Ltd | Professional & scientific | 2024 |
| Medical Tourism Africa Limited | Information & communication | 2025 |
| Medicareplus International Ltd | Manufacturing | 2007 |
| Medichef Limited | Hospitality | 2019 |
| Medicine Box (London) Ltd | Health & social care | 2018 |
| Medipoint UK Ltd | Wholesale & retail | 2022 |
| Medisiya Group Limited | Real estate | 2023 |
| Medisiya Ltd | Health & social care | 2021 |
| Medit Property Limited | Construction | 2022 |
| Medlife Solutions Ltd | Health & social care | 2023 |
| Medobay Ltd | Wholesale & retail | 2018 |
| Medpharm Solutions Ltd | Health & social care | 2026 |
| Medvis Consult Ltd | Health & social care | 2023 |
| Meeforce Ltd | Administrative & support | 2020 |
| Meeshu Enterprises Ltd | Manufacturing | 2026 |
| Meeshu Food & Wine Ltd | Wholesale & retail | 2025 |
| Meet Builders Ltd | Construction | 2026 |
| Mega Heaters UK Ltd | Wholesale & retail | 2026 |
| Mega Spyro Ltd | Real estate | 2014 |
| Megabuild Construction Ltd | Construction | 2012 |
| Megan Ceramica Limited | Wholesale & retail | 2025 |
| Meghan Dias Ltd | Hospitality | 2024 |
| Meghji Optical Ltd | Health & social care | 2022 |
| Mehadrin Wholesale Limited | Wholesale & retail | 1999 |
| Mehar Mart Ltd | Wholesale & retail | 2025 |
| Mehdy Law Limited | Professional & scientific | 2024 |