| Meadowview Management Limited | Real estate | 1974 |
| Medanik Ltd | Health & social care | 2010 |
| Medi FIX Ltd | Health & social care | 2020 |
| Medi Glow Aesthetics & Health UK Ltd | Professional & scientific | 2009 |
| Medi-Trading UK Limited | Health & social care | 2006 |
| Media Savvy Ltd | Professional & scientific | 2026 |
| Mediasharp Ltd | Information & communication | 2015 |
| Medichnology Limited | Professional & scientific | 2018 |
| Mediclique Ltd | Health & social care | 2025 |
| Medico Limited | Wholesale & retail | 2005 |
| Medicoss Limited | Health & social care | 2020 |
| Mediqual Ltd | Public administration | 2020 |
| Medmentor Limited | Education | 2019 |
| Medtech Services Ltd | Health & social care | 2015 |
| Medway Residences Limited | Administrative & support | 2005 |
| Meeking Rigging Ltd | Other services | 2013 |
| Meer Ecom Store Ltd | Wholesale & retail | 2025 |
| Meera's Catering Limited | Hospitality | 2021 |
| Meerco Ltd | Hospitality | 2021 |
| Meet Developers Limited | Construction | 2024 |
| Meetly Limited | Information & communication | 2026 |
| Mega Transfers London Limited | Transport & logistics | 2023 |
| Megacom Limited | Wholesale & retail | 2002 |
| Mehdi Global Ltd | Wholesale & retail | 2025 |
| Mehek Pharma Ltd | Wholesale & retail | 2023 |
| Mehr Consultancy Ltd | Information & communication | 2017 |
| Mehran Esmaili Ltd | Other services | 2026 |
| Mehta Estates Limited | Real estate | 2018 |
| Meier Architects Limited | Professional & scientific | 2020 |
| Meine Europe Limited | Wholesale & retail | 2002 |
| Mekss Ltd | Real estate | 2010 |
| Melian Dialogue Research Limited | Professional & scientific | 2018 |
| Melimart Ltd | Transport & logistics | 2023 |
| Melinda Property Investments 2 Limited | Real estate | 2023 |
| Melrose Avenue (Residents) Association Limited | Households | 1988 |
| Melrose Court (Management) Company Limited | Real estate | 1979 |
| Mema Limited | Construction | 2007 |
| Memes Firm Ltd | Information & communication | 2019 |
| Memorybox Decor Ltd | Hospitality | 2022 |
| Menacred UK Limited | Information & communication | 2023 |
| Menazel Ltd | Administrative & support | 2015 |
| Mentor Somalia Ltd | Arts & recreation | 2014 |
| Mentus Novum Ltd | Professional & scientific | 2025 |
| MEP Design Management Limited | Professional & scientific | 2014 |
| Meralis Insight Ltd | Professional & scientific | 2024 |
| Mercury Specialist Handling Limited | Financial services | 2024 |
| Meridian Removals Ltd | Transport & logistics | 2023 |
| Merit Cleaning Services Limited | Administrative & support | 2001 |
| Mermox Ltd | Professional & scientific | 2023 |
| Meso Investment LLP | | 2013 |
| MET 2 LET Ltd | Real estate | 2024 |
| MET Connections Ltd | Construction | 2022 |
| MET Global Services Ltd | Financial services | 2024 |
| MET TM Solutions Ltd | Manufacturing | 2024 |
| Meta Hitech Kitchen Equipments Limited | Wholesale & retail | 2022 |
| META1ST Buckinghamshire Limited | Information & communication | 2024 |
| Metal Parts Limited | Manufacturing | 2011 |
| Metal Recycling Centre Ltd | Manufacturing | 2025 |
| Methmini Property Ltd | Real estate | 2019 |
| Metrane Services Ltd. | Construction | 2015 |
| Metrix Commercial Interiors Limited | Administrative & support | 2001 |
| Metro Engineering and Plating Works Limited | Manufacturing | 1946 |
| Metro Immigration Specialists Ltd | Professional & scientific | 2015 |
| Metro Traders Limited | Information & communication | 2006 |
| Metropole Hayes Ltd | Other services | 2021 |
| Metropolis Construction Limited | Construction | 2020 |
| Metropolitan House Investments (U.K.) Limited | Real estate | 2017 |
| Metts Limited | Manufacturing | 2004 |
| MF Property Services Ltd | Administrative & support | 2018 |
| MG Facades Ltd | Construction | 2025 |
| MG Human Rights Legal Services Ltd | Professional & scientific | 2025 |
| Mgateway Ltd | Information & communication | 2023 |
| Mgrtransport Ltd | Transport & logistics | 2023 |
| MH Carpentry Ltd | Information & communication | 2024 |
| MH Turi Limited | Administrative & support | 2012 |
| MHS Management Limited | Real estate | 1987 |
| Mi&A Consultants Limited | Construction | 2022 |
| Miah Construct Ltd | Construction | 2024 |
| Miand Co Ltd | Wholesale & retail | 2026 |
| MIC Property Ltd | Real estate | 2021 |
| Michael Crompton (London) Limited | Information & communication | 2008 |
| Michael Leigh (CCA) Limited | Professional & scientific | 2010 |
| Michael Nappi Limited | Information & communication | 2021 |
| Michael Oakes Architects Limited | Professional & scientific | 2018 |
| Michael Sergio Holding Limited | Financial services | 2025 |
| Michea Drylining Ltd | Construction | 2024 |
| Michelle and Micah Ltd | Financial services | 2019 |
| Michelle Gore UDS Limited | Health & social care | 2026 |
| Micro MAX Property Ltd | Real estate | 2026 |
| Micro Plus Software Limited | Administrative & support | 1993 |
| Microapps UK Ltd | Wholesale & retail | 2021 |
| Micronutrients Ltd | Wholesale & retail | 2012 |
| Midas REG Limited | Wholesale & retail | 2013 |
| Middlesex County Automobile Club Limited | Other services | 1974 |
| Middlesex Energy Solutions Ltd | Wholesale & retail | 2013 |
| Middlesex Law Chambers Ltd | Professional & scientific | 2024 |
| Middlesex Mobile Mechanic Ltd | Wholesale & retail | 2023 |
| Middlesex Readymix Concrete (London) Limited | Extraterritorial | 2022 |
| Midgas GAS Services Ltd | Construction | 2016 |
| Midlex Ltd | Construction | 2026 |