| Martin Allen (Training & Consultancy) Ltd | Professional & scientific | 2006 |
| Masterbond Investments Limited | Professional & scientific | 2005 |
| Matchbox Films Limited | Information & communication | 2009 |
| Matchking Limited | Administrative & support | 2006 |
| Matt COX Consulting Ltd | Professional & scientific | 2026 |
| Matthew Bennett Solutions Ltd | Construction | 2026 |
| Matthew Clark Renovations Ltd | Construction | 2020 |
| MAX Care & Mobility Ltd | Wholesale & retail | 2014 |
| Mayfield Property Limited | Real estate | 2022 |
| Maylands Golf and Country Club Limited | Arts & recreation | 2023 |
| MBL Rentals Ltd | Real estate | 2020 |
| MBR Advisory Limited | Administrative & support | 2025 |
| MC Bucsa Ltd | Transport & logistics | 2022 |
| Mcbain International Limited | Professional & scientific | 2003 |
| ME Recruitment Solutions Limited | Administrative & support | 2011 |
| ME Systems Limited | Professional & scientific | 2024 |
| Meadow Fields (East Ayton) Management Company Limited | Households | 2024 |
| Meadow Wood Chertsey Limited | Real estate | 2018 |
| Meadow Wood Developments Limited | Construction | 2014 |
| Meadow Wood Properties Limited | Real estate | 2017 |
| Medical Consultant Ltd | Health & social care | 2024 |
| Megacarrier Group Company Limited | Manufacturing | 2025 |
| Meihua Culture Limited | Arts & recreation | 2013 |
| Melrose Holdings Limited | Financial services | 2023 |
| Merchants Quay Residential Company Limited | Households | 2011 |
| Merton Place Care Limited | Health & social care | 2022 |
| Mertonplace Limited | Professional & scientific | 1986 |
| Metaa Construction Ltd | Construction | 2021 |
| Miai Brand Partnerships Limited | Professional & scientific | 2011 |
| Miai Holdings Ltd | Financial services | 2026 |
| Michael Page Employment Services Ltd | Administrative & support | 2005 |
| Michael Page Holdings Limited | Administrative & support | 1984 |
| Michael Page International 1982 Limited | Administrative & support | 1982 |
| Michael Page International Finance Limited | Professional & scientific | 1988 |
| Michael Page International Holdings Limited | Financial services | 1988 |
| Michael Page International Investment Limited | Professional & scientific | 1988 |
| Michael Page International Limited | Professional & scientific | 1988 |
| Michael Page International Recruitment Limited | Administrative & support | 2000 |
| Michael Page International Southern Europe Limited | Professional & scientific | 2000 |
| Michael Page Limited | Administrative & support | 1982 |
| Michael Page Partnership Limited | Professional & scientific | 1983 |
| Michael Page Recruitment Group Limited | Professional & scientific | 1988 |
| Michael Page UK Limited | Administrative & support | 1976 |
| Micro Computer Disks Limited | Real estate | 1983 |
| Millenium Trans Ltd | Wholesale & retail | 2017 |
| Millennium Star Limited | Wholesale & retail | 2008 |
| Mind Bearer Ltd. | Health & social care | 2020 |
| Mind Warriors (Addlestone) CIC | Education | 2026 |
| Minster Care Cheaney Limited | Health & social care | 2015 |
| Minster Care Ealing Limited | Health & social care | 2019 |
| Minster Care Limited | Health & social care | 2021 |
| Minster Care Management NO2 Limited | Health & social care | 2025 |
| Minster Care Services Limited | Health & social care | 2020 |
| Mintedcars Ltd | Wholesale & retail | 2026 |
| Miracle by J&J Ltd | Health & social care | 2016 |
| Mistcroft Limited | Administrative & support | 2010 |
| MJI Projects Ltd | Information & communication | 2024 |
| MJM Management Services Limited | Professional & scientific | 2017 |
| MK Flooring Ltd | Construction | 2025 |
| MLS Nutrition Limited | Wholesale & retail | 2024 |
| MM Fire Services Limited | Construction | 2013 |
| MMW Project Services Limited | Professional & scientific | 2024 |
| Moat Court Residents Company Limited | Households | 1981 |
| Mobile Barber Ltd | Other services | 2017 |
| Mobile Metal Masters Limited | Manufacturing | 2025 |
| Modstyle Eyewear UK Limited | Wholesale & retail | 2022 |
| Monaco Residency Services Ltd. | Information & communication | 2019 |
| Monarch Global Exchange Limited | Wholesale & retail | 2020 |
| Moneysatnav UK Ltd. | Information & communication | 2021 |
| Mongeau Capital Limited | Extraterritorial | 2014 |
| Monlicious Ltd | Hospitality | 2017 |
| MONOLIT73 Limited | Transport & logistics | 2018 |
| Montdev Ltd | Real estate | 2026 |
| Montega Limited | Manufacturing | 2014 |
| Monteiro Logistics Ltd | Transport & logistics | 2021 |
| Monument Court (Weybridge) Limited | Households | 2004 |
| Moonbuild Surrey Ltd | Construction | 2017 |
| Moore and Smythson Properties Limited | Real estate | 2019 |
| Mossgroves LLP | | 2006 |
| Mountbatten Homes Limited | Construction | 2018 |
| Mousebark Films Limited | Information & communication | 2025 |
| Movie Makers Limited | Extraterritorial | 2009 |
| Moviesweep Limited | Information & communication | 2014 |
| MR Multitask Ltd | Other services | 2023 |
| MR Sparkles Car Wash Ltd | Other services | 2015 |
| MS Scooters Ltd | Wholesale & retail | 2023 |
| Msmg Consultancy Limited | Construction | 2010 |
| Mtec Security Solutions Limited | Administrative & support | 2019 |
| Mulberry Manor Ltd | Extraterritorial | 2010 |
| Mullion Management Company Limited | Hospitality | 1988 |
| Multi Sports Development Centres Ltd | Arts & recreation | 2009 |
| Munzel Limited | Real estate | 2025 |
| Musical Adventures Ltd | Health & social care | 2023 |
| Musicbyremedy Ltd | Information & communication | 2024 |
| Mutters Ltd | Financial services | 2025 |
| MVM Motors Ltd | Wholesale & retail | 2023 |
| MWD Studios Ltd | Information & communication | 2024 |
| My Elysium Limited | Real estate | 2023 |
| My Hero Group Ltd | Administrative & support | 2020 |
| Myaviation Limited | Professional & scientific | 2014 |