| Maysoft Ltd | Information & communication | 2024 |
| Mazo 2025 Ltd | Hospitality | 2025 |
| MB Lashes Ltd | Other services | 2026 |
| Mbgallagher Limited | Professional & scientific | 2014 |
| Mcconnell Law Limited | Professional & scientific | 2012 |
| Mccoy Technology Ltd | Information & communication | 2026 |
| Mckinsky & Co Ltd | Professional & scientific | 2025 |
| Mclaughlan Media Ltd | Information & communication | 2011 |
| Mcmx Limited | Professional & scientific | 2018 |
| Mcomms Ltd | Professional & scientific | 2025 |
| Mdmarket Ltd | Wholesale & retail | 2020 |
| Mdrgsc Limited | Wholesale & retail | 2023 |
| Mdth Property Limited | Real estate | 2025 |
| ME Telecom Limited | Wholesale & retail | 2023 |
| Meadway Twickenham Residents Management Limited | Real estate | 1981 |
| Mecha Engineering Limited | Manufacturing | 2023 |
| Mecon Developments Limited | Financial services | 2016 |
| Media Singh Ltd | Professional & scientific | 2017 |
| Medical Aide Memoire Ltd. | Health & social care | 2018 |
| Mediedit Limited | Professional & scientific | 2015 |
| Meditorial Associates Limited | Information & communication | 2012 |
| Meehan Heating Limited | Construction | 2021 |
| Meenakshi Limited | Professional & scientific | 2021 |
| Megalon Ltd | Information & communication | 2011 |
| Megi Jewellery Limited | Wholesale & retail | 2025 |
| Meirion Advisory Services Limited | Professional & scientific | 2022 |
| Mekhanism Ltd | Information & communication | 2018 |
| Melbourne Court (Twickenham) Residents' Association Limited | Households | 1986 |
| Melior Appointments Ltd | Administrative & support | 2014 |
| Melior Digital Ltd | Administrative & support | 2015 |
| Mellow 9 Productions Ltd | Information & communication | 2009 |
| Mental Health & Wellness Ltd | Health & social care | 2020 |
| Meraki Aesthetics Ltd | Other services | 2017 |
| Mergen Limited | Information & communication | 2019 |
| Meri Blue Limited | Hospitality | 2026 |
| Merritt Media Ltd | Arts & recreation | 2014 |
| Meshi Contractors Ltd | Construction | 2017 |
| Meshi Properties Ltd | Real estate | 2024 |
| Message My Customer UK Limited | Information & communication | 2026 |
| Metavello Limited | Administrative & support | 2014 |
| Meter Rental Collections Limited | Information & communication | 2020 |
| Metrika CGN Limited | Manufacturing | 2021 |
| Metrika Science (IP) Limited | Professional & scientific | 2019 |
| Metrika Science (R&D) Limited | Manufacturing | 2019 |
| Metsi Affiliate Connections Limited | Administrative & support | 2019 |
| Metsphere Limited | Information & communication | 2020 |
| Mevans Property Holdings Ltd | Real estate | 2025 |
| Meyer & Themis Ltd | Professional & scientific | 2017 |
| MF Greenscapes Ltd | Administrative & support | 2025 |
| MFG Enterprise Ltd | Real estate | 2022 |
| Mfsg Investment Property Limited | Real estate | 2024 |
| MG Lighting Limited | Construction | 2009 |
| MHH Accountancy Services Limited | Professional & scientific | 2015 |
| MHK Trading UK Limited | Wholesale & retail | 2024 |
| MI Vida Aesthetic Clinic Ltd. | Other services | 2020 |
| MI Vida Aesthetic Training Academy Ltd | Professional & scientific | 2024 |
| Miac Analytics Limited | Professional & scientific | 2009 |
| Mica Fine Limited | Manufacturing | 2016 |
| Micheal Fish Bar Limited | Hospitality | 2013 |
| Mick's Roofing & Guttering Ltd | Construction | 2025 |
| Micro Tech London Limited | Information & communication | 2019 |
| MID Beds Pensions & Investments Ltd | Financial services | 2012 |
| Middlesex Masonic Development Fund Limited | Other services | 1994 |
| Middlesex Reclaim & Waste Collection Limited | Water & waste | 2017 |
| Mike Parker Consulting Ltd | Professional & scientific | 2009 |
| Milahairdressers Ltd | Other services | 2016 |
| Milan Services (UK) Ltd | Information & communication | 2011 |
| Milestone Investment Services Limited | Construction | 2020 |
| Milford Property Holdings Limited | Real estate | 2021 |
| Milk & Honey Gourmet Grocer Ltd | Wholesale & retail | 2021 |
| Milkshake Montessori Limited | Education | 2009 |
| Millstone Cafe Ltd | Hospitality | 2026 |
| Milton Jones Limited | Arts & recreation | 2002 |
| Mimi Blue Records Limited | Professional & scientific | 2022 |
| Mindfit Bodyfit Limited | Professional & scientific | 2011 |
| Mindwarp Ltd. | Information & communication | 2006 |
| Mineral Treasures Limited | Wholesale & retail | 2002 |
| Minexia Nominees Limited | Mining & quarrying | 2022 |
| Mingled Marketing Ltd | Professional & scientific | 2021 |
| Mini Project Shipping Ltd | Transport & logistics | 2015 |
| Minx PR Ltd | Professional & scientific | 2005 |
| Miowash Limited | Manufacturing | 2024 |
| MIP Building and Plastering Ltd | Construction | 2025 |
| MIP Construction Ltd | Construction | 2015 |
| Mira Technology Ltd | Information & communication | 2025 |
| Mirb Ltd | Transport & logistics | 2019 |
| Mirror Consulting Ltd | Arts & recreation | 2014 |
| Miseno Ltd | Construction | 2021 |
| Miss Siam Restaurants Limited | Real estate | 1995 |
| Mister James London Ltd | Extraterritorial | 2018 |
| Mizpah Software Solutions Ltd | Information & communication | 2016 |
| MJ Financial Planning Limited | Financial services | 2020 |
| MJA Eyewear Ltd | Wholesale & retail | 2024 |
| MJB Consultancy Limited | Professional & scientific | 2003 |
| MJM Strategies Ltd | Professional & scientific | 2024 |
| Mjmt Limited | Financial services | 2021 |
| MJS Complete Electrical Limited | Construction | 2020 |
| MJS Enterprises Limited | Real estate | 2024 |
| MJS Mortgage Consultants Ltd | Financial services | 2005 |
| Mjsb Investments Ltd | Real estate | 2021 |