| Matthew Hall Consulting Limited | Information & communication | 2015 |
| Matthew Lane Associates Ltd | Administrative & support | 2021 |
| Matthew Selt Snooker Limited | Administrative & support | 2015 |
| Mattjim Innovation Ltd | Professional & scientific | 2025 |
| Mattos Commercial Enterprises Ltd | Health & social care | 2020 |
| Mattrans-Link Global Limited | Wholesale & retail | 2025 |
| Matzoros Ltd | Transport & logistics | 2021 |
| Mauble Care Limited | Health & social care | 2025 |
| Mauble Limited | Health & social care | 2025 |
| Mauger Brothers Limited | Construction | 2025 |
| Maurice CAY Consultancy Ltd | Professional & scientific | 2009 |
| Maverick Ingenuity Ltd | Professional & scientific | 2023 |
| Maverick Sea Crossings Limited | Administrative & support | 2016 |
| Maverika Ltd | Information & communication | 2023 |
| Mavhera Ltd | Information & communication | 2019 |
| Mavicsfragrance Limited | Wholesale & retail | 2025 |
| Mawney Partners Limited | Administrative & support | 2013 |
| MAX Adams Limited | Financial services | 2012 |
| MAX Exertion Athletics Ltd | Arts & recreation | 2015 |
| MAX Volt Productions Limited | Professional & scientific | 2014 |
| Maxas Construction Limited | Construction | 2025 |
| Maxas Design and Build Limited | Construction | 2016 |
| Maxas Development Limited | Professional & scientific | 2026 |
| Maxas Electrical Ltd | Construction | 2025 |
| Maxas Holding Ltd | Financial services | 2025 |
| Maxas Homes Ltd | Real estate | 2025 |
| Maxas Plumbing and Heating Ltd | Construction | 2025 |
| Maxgrace UK Ltd | Wholesale & retail | 2026 |
| Maxidore Holdings Limited | Financial services | 2024 |
| Maximum Leverage Limited | Financial services | 2014 |
| Maximum VR Ltd | Information & communication | 2021 |
| Maximus Apen IT Consultancy Ltd | Information & communication | 2019 |
| Maximus Build Ltd | Construction | 2025 |
| Maximusr Ltd | Manufacturing | 2017 |
| Maxitile Limited | Construction | 2007 |
| MAXITRANSPORT7 Ltd | Transport & logistics | 2025 |
| Maxiviotransport Ltd | Transport & logistics | 2025 |
| Maxjam Services 247 Ltd | Health & social care | 2022 |
| Maxkebab Ltd | Hospitality | 2025 |
| Maxmd Ltd | Transport & logistics | 2025 |
| Maxmyles Holdings Limited | Financial services | 2026 |
| Maxs Services Ltd | Construction | 2023 |
| Maxtradepro Limited | Wholesale & retail | 2020 |
| Maxvue Limited | Information & communication | 2021 |
| Maxwell Facilities Management Ltd | Administrative & support | 2010 |
| Maxwell International Limited | Wholesale & retail | 2024 |
| Maxwood Music Limited | Other services | 1984 |
| Maxword Ltd | Wholesale & retail | 2023 |
| MAY Business Consulting Ltd | Information & communication | 2014 |
| Maya Thai Massage Limited | Health & social care | 2025 |
| Maya&Miru Ltd | Transport & logistics | 2025 |
| Mayan Holdings Limited | Financial services | 2025 |
| Maya’S Sensory & Support Hub CIC | Health & social care | 2026 |
| Mayberry Counselling Ltd | Education | 2025 |
| Maybrey Ltd | Administrative & support | 2022 |
| Maycor UK Limited | Hospitality | 2003 |
| Maydom Properties Ltd | Real estate | 2021 |
| Mayfair Benefits Ltd | Professional & scientific | 2026 |
| MAYFAIRBEEF1 Ltd | Hospitality | 2025 |
| Mayfield Brown | Financial services | 2017 |
| Mayhem Fitness MK Ltd | Arts & recreation | 2020 |
| Mayhew Performing Arts Limited | Arts & recreation | 2020 |
| Maylark Limited | Professional & scientific | 2001 |
| Mayo Alumni UK Ltd | Other services | 2025 |
| Mayombwe Associates Limited | Financial services | 2017 |
| Mayor Brickwork Ltd | Construction | 2021 |
| Mayson Property Limited | Real estate | 2021 |
| Maytree Consultancy Ltd | Information & communication | 2013 |
| Mayx Limited | Financial services | 2021 |
| Mayyam's Cafe Ltd | Hospitality | 2024 |
| Mayyam's Kitchen Limited | Hospitality | 2024 |
| MAZ RG1 Foods Ltd | Hospitality | 2021 |
| Mazal Limited | Administrative & support | 2002 |
| Mazark Tech Ltd | Information & communication | 2021 |
| Maze Limited | Information & communication | 2022 |
| Mazeblock Limited | Construction | 1987 |
| Mazfam | Financial services | 2025 |
| Mazny Smiles Ltd | Health & social care | 2021 |
| Mazur Trans Ltd | Transport & logistics | 2015 |
| MB Caravans Ltd | Wholesale & retail | 2017 |
| MB Civil Engineering Ltd | Construction | 2023 |
| MB Driver (UK) Ltd | Transport & logistics | 2014 |
| MB MK Property Limited | Real estate | 2025 |
| MB Plumbing & Facilities Ltd | Construction | 2026 |
| MB Securenet Ltd | Information & communication | 2010 |
| MBA Group Holdings Limited | Financial services | 2023 |
| Mbandm Limited | Administrative & support | 2016 |
| MBC Trading Limited | Wholesale & retail | 2024 |
| MBD Sales Limited | Professional & scientific | 2010 |
| Mbeauty PMU Limited | Other services | 2024 |
| MBM & Sons Company Ltd | Hospitality | 2016 |
| MBN Services Limited | Construction | 2017 |
| MBP Construction Ltd | Construction | 2015 |
| MBR Cars Ltd | Transport & logistics | 2024 |
| MBS Contractors-Uk Ltd | Construction | 2019 |
| MBT Concept Ltd | Construction | 2020 |
| MBW Wealth Management Ltd | Professional & scientific | 2020 |
| MC Draughting Ltd | Professional & scientific | 2018 |
| MC Excellent Floors & Walls Ltd | Construction | 2018 |
| MC Property Surveyors Limited | Professional & scientific | 2024 |