| Matahari 418 Limited | Professional & scientific | 1991 |
| Mathew & Daughter's Care Service Ltd. | Health & social care | 2016 |
| Mathew & Daughters Ltd | Real estate | 2020 |
| Matlock Holdings Ltd | Other services | 2019 |
| Matrixvisuals Limited | Professional & scientific | 2024 |
| Matt Brown Air Conditioning Limited | Manufacturing | 2016 |
| Matt Marsh Photography Ltd | Professional & scientific | 2021 |
| Matt Screen Pet Services Ltd | Other services | 2018 |
| Matthew Clulee Limited | Other services | 2005 |
| Maua Systems Ltd | Information & communication | 2025 |
| Maulin Capital Ltd | Financial services | 2022 |
| Maulin Group Ltd | Financial services | 2025 |
| Maulin Law Limited | Professional & scientific | 2022 |
| Maulin Risk Partners Ltd | Administrative & support | 2025 |
| Maverick Electrical Installations Ltd | Construction | 2025 |
| Mavex Catering Ltd | Hospitality | 2019 |
| MAX Smart Digital Ltd | Information & communication | 2021 |
| MAX Ukcn Ltd | Administrative & support | 2025 |
| Maximor Ltd | Manufacturing | 2023 |
| Maxmud Ltd | Hospitality | 2023 |
| Maxson Construction Ltd | Construction | 2010 |
| Maxted Property Management Limited | Real estate | 2020 |
| Maxxed OUT Kicks Ltd | Wholesale & retail | 2025 |
| MAY Concepts Ltd | Arts & recreation | 2015 |
| Maybird Training Ltd | Education | 2019 |
| Mayfair Berkeley Solutions Ltd | Professional & scientific | 2025 |
| Maylands Consulting Kent Ltd | Professional & scientific | 2009 |
| Maymax Homes Ltd | Construction | 2023 |
| Maypole Marquee Limited | Administrative & support | 2003 |
| Maysum Ltd | Real estate | 2024 |
| Mayville Properties Ltd | Real estate | 2013 |
| Mayviv Ltd | Construction | 2018 |
| Maza London Ltd | Real estate | 2023 |
| Mazdr Property Ltd | Real estate | 2020 |
| Mazmacorp Ltd | Information & communication | 2023 |
| MB Construction Services (S.E) Ltd | Construction | 2025 |
| MB Roofing & Leadwork Ltd | Construction | 2022 |
| MB Sky Relocations Ltd | Transport & logistics | 2024 |
| MB42 Engineering Ltd | Water & waste | 2023 |
| MBA Backstage Ltd | Other services | 2018 |
| MBA Heating Plumbing and Maintenance Ltd | Construction | 2025 |
| MBE Properties South East Limited | Real estate | 2023 |
| MBG Construction (UK) Limited | Construction | 2012 |
| MBH Media Consultancy Limited | Professional & scientific | 2014 |
| Mbhs Building Solutions Limited | Construction | 2023 |
| Mbhs Holdings Limited | Real estate | 2024 |
| Mbhs Investments Limited | Real estate | 2019 |
| Mbko Services Limited | Administrative & support | 2013 |
| Mbrc Limited | Professional & scientific | 2020 |
| MC Carpentry and Construction Ltd | Construction | 2018 |
| MC Civils Limited | Construction | 2024 |
| MC International Properties Ltd | Other services | 2016 |
| MC Testing Services Limited | Construction | 2005 |
| MCC Technical Group Ltd | Professional & scientific | 2026 |
| Mccabes Treat Company Ltd | Wholesale & retail | 2026 |
| Mcdonald Builders (Surrey) Ltd | Real estate | 2019 |
| Mcintosh Make-Up Limited | Arts & recreation | 2011 |
| Mclaren Anderson Consulting Ltd | Wholesale & retail | 2018 |
| Mcleod Building Consultancy Limited | Construction | 2005 |
| Mcooper Limited | Health & social care | 2025 |
| Mcqueens Ltd | Hospitality | 2026 |
| Mcwan Ltd | Information & communication | 2020 |
| Mcwd Limited | Professional & scientific | 2017 |
| MD Business Sales Limited | Wholesale & retail | 2014 |
| MD Property and Land Ltd | Construction | 2023 |
| MD Training Consultancy Limited | Information & communication | 2010 |
| Mddc Limited | Construction | 2017 |
| MDN Controls Limited | Construction | 2026 |
| MDN UK Limited | Construction | 2005 |
| MDR South East Ltd | Administrative & support | 2024 |
| MDX Transport Ltd | Transport & logistics | 2020 |
| ME, Mummy & I Ltd | Health & social care | 2022 |
| ME55NOT Services Limited | Construction | 2021 |
| ME8 Property Solutions Limited | Construction | 2020 |
| Mead Developments Limited | Construction | 2014 |
| Mead Electrical Services Essex Ltd | Construction | 2024 |
| Meadow View (the Forstal) Limited | Households | 2018 |
| Meadow View (WW) Management Company Limited | Real estate | 1999 |
| Meas Group Limited | Professional & scientific | 2016 |
| Meatmaster Holdings Limited | Financial services | 2020 |
| Mechanical Electrical Civils Utilities Ltd | Construction | 2023 |
| Meclec (Elec-Services) Limited | Energy | 2014 |
| MED Nexus Ltd | Education | 2026 |
| MED Pharma Developments Limited | Professional & scientific | 2024 |
| MED SEC Solution Ltd | Health & social care | 2026 |
| Medash Signs Limited | Manufacturing | 1987 |
| Medcar Auto Center Ltd | Wholesale & retail | 2024 |
| Medcomm Consulting PVT Ltd | Professional & scientific | 2025 |
| Media Village Holdings Limited | Financial services | 2019 |
| Media Village PR Limited | Professional & scientific | 1996 |
| Media Village Properties LLP | | 2003 |
| Media Village Property Limited | Households | 2020 |
| Media-Sans-Frontieres Limited | Arts & recreation | 2011 |
| Mediaweb Global Limited | Administrative & support | 2008 |
| Medic Healthcare Ltd | Financial services | 2015 |
| Medical Doctor Services Limited | Health & social care | 2022 |
| Medical Imaging Consultancy Limited | Manufacturing | 2001 |
| Medical Technology Limited | Manufacturing | 2021 |
| Medicborhan Ltd | Health & social care | 2022 |
| Medicentre Surrey Ltd | Health & social care | 2025 |