| Master Movers Removals & Storage Ltd | Transport & logistics | 2025 |
| Master the Chain Ltd | Education | 2025 |
| Masters Development Visions Ltd | Professional & scientific | 2017 |
| Masters Marble Ltd | Construction | 2017 |
| Mat&Ada Ltd | Manufacturing | 2024 |
| Mata Brothers Plumbing Limited | Construction | 2016 |
| Matco Group Ltd | Construction | 2021 |
| Matharu Asset Management Ltd | Real estate | 2019 |
| Mathi Picturess Limited | Information & communication | 2025 |
| Mati Recovery Ltd | Administrative & support | 2024 |
| Matlock Homes Limited | Construction | 1992 |
| Matras Haulage Ltd | Transport & logistics | 2025 |
| Matrix Communication Group Ltd. | Information & communication | 2018 |
| Matrix Escape Consulting Ltd | Education | 2026 |
| Matta Building & Maintenance Services Ltd | Construction | 2017 |
| Matta Kitchen and Bedroom Ltd | Construction | 2024 |
| Matta Property Investments Ltd | Real estate | 2020 |
| Mattalb Ltd | Construction | 2023 |
| Matthew J Tresidder Properties Ltd | Real estate | 2022 |
| Mattoni Constructions Ltd | Real estate | 2025 |
| MAX Learning Ltd | Professional & scientific | 2012 |
| Mayalita Ltd | Manufacturing | 2023 |
| Mayan Property Investment Limited | Real estate | 2021 |
| Mayfair Aurum Ltd | Wholesale & retail | 2026 |
| Mayfair Grooming Ltd | Other services | 2024 |
| Mayfair Pets Limited | Manufacturing | 2025 |
| Mayfair Restaurants Limited | Hospitality | 1995 |
| Mayfair Shopping Limited | Wholesale & retail | 2024 |
| Maygrove Interior & Design Ltd | Administrative & support | 2019 |
| MB Construct Ltd | Construction | 2012 |
| MB Healthcare and Consultancy Limited | Health & social care | 2019 |
| Mbari Limited | Administrative & support | 2017 |
| MBM Fragrance Limited | Wholesale & retail | 2021 |
| MBM Global Trade Ltd | Wholesale & retail | 2022 |
| MBS Hospitality Limited | Hospitality | 2025 |
| Mbzn Ltd | Professional & scientific | 2022 |
| MC Digital Limited | Information & communication | 2025 |
| MC Digital Television Productions Limited | Information & communication | 2023 |
| MC Marron Group Limited | Professional & scientific | 2013 |
| MCC Middx Limited | Construction | 2007 |
| MCD Crushing & Plant Hire Limited | Water & waste | 2021 |
| Mcdaid Brothers Contractors Limited | Extraterritorial | 2002 |
| Mcginley Contractors Limited | Construction | 2019 |
| Mcpl Ceramic Limited | Wholesale & retail | 2023 |
| Mcrail Constructions Limited | Construction | 2012 |
| Mcray & Associates Ltd | Other services | 2024 |
| Mcray Ltd | Other services | 2025 |
| MD & Audrey Properties Ltd | Construction | 2020 |
| MD & Audrey Services Ltd | Real estate | 2022 |
| MDA Home Ltd | Wholesale & retail | 2012 |
| MDD Recruitment Services Limited | Administrative & support | 2026 |
| MDK Property Management Limited | Other services | 2019 |
| Meadow Trading Estate Limited | Real estate | 1987 |
| Meads Healthcare Limited | Wholesale & retail | 2022 |
| Meamar Ltd | Professional & scientific | 2012 |
| Medhealthpro Ltd | Health & social care | 2023 |
| Media Incognito Limited | Information & communication | 2016 |
| Medical Cleaning Ltd | Administrative & support | 2009 |
| Medical Horizons Limited | Health & social care | 2004 |
| Medici Wealth Limited | Professional & scientific | 2022 |
| Medicus Polish Medical Practice Ltd | Health & social care | 2024 |
| Mediteam Ltd | Health & social care | 2024 |
| Mediterranean Food Products Limited | Wholesale & retail | 1999 |
| Medstaar Limited | Administrative & support | 2012 |
| Medsurg Services Limited | Health & social care | 2025 |
| Meeras Investments Limited | Real estate | 2024 |
| Meeta BTL Ltd | Real estate | 2025 |
| Meeta Ltd | Real estate | 2015 |
| Mehta Films Ltd | Administrative & support | 2020 |
| Mehulandwork Limited | Administrative & support | 2025 |
| Meje Ltd | Transport & logistics | 2026 |
| Mela Property Management Services Ltd | Real estate | 2021 |
| Meley Limited | Real estate | 2015 |
| Meli & Artos Limited | Manufacturing | 2023 |
| Melvin Peter D Douza Ltd | Construction | 2023 |
| Mena Alternatives Ltd | Information & communication | 2025 |
| Mentormind Education Ltd | Information & communication | 2025 |
| MERAKI.27 Ltd | Transport & logistics | 2022 |
| Mercury Electronic Services Limited | Manufacturing | 2019 |
| Mesmerine Ltd | Wholesale & retail | 2025 |
| Messios Ltd. | Real estate | 2022 |
| Meta Solutions Ltd. | Information & communication | 2020 |
| Metablend Ltd | Information & communication | 2024 |
| Metagedu Apprenticeships Ltd | Education | 2014 |
| Metalliq Ltd | Professional & scientific | 2025 |
| Metro Travel Agent UK Limited | Administrative & support | 2021 |
| Metro Waterproofing Limited | Construction | 2023 |
| MG Auto Repairs Limited | Wholesale & retail | 2012 |
| MG Next GEN Install Ltd | Construction | 2026 |
| Mgjp Consultancy Ltd | Real estate | 2020 |
| MGM Global Solutions Ltd | Mining & quarrying | 2017 |
| Mh&A Electrical Building Limited | Construction | 2023 |
| Mhabboud Ltd | Professional & scientific | 2023 |
| Mhrn Limited | Wholesale & retail | 2023 |
| MI Boost Limited | Wholesale & retail | 2025 |
| MIA Property Partners LLP | | 2026 |
| Michael Hirst Ltd | Arts & recreation | 2013 |
| Micro World Bookkeeping Service Limited | Information & communication | 2019 |
| Micronwireless Limited | Manufacturing | 2008 |
| Microstar Limited | Other services | 2018 |