| Marketing Vision Consultancy Ltd. | Professional & scientific | 2015 |
| Marldell Medical Limited | Extraterritorial | 2020 |
| Marldell Water Limited | Water & waste | 2013 |
| Marlenson Ltd | Professional & scientific | 2025 |
| Marmalise Limited | Health & social care | 2010 |
| Maronway Construction Limited | Construction | 2013 |
| Marshall FP Limited | Financial services | 2025 |
| Martin Banasik Consulting Ltd | Professional & scientific | 2021 |
| Masoncast Limited | Manufacturing | 2017 |
| Matrix Consulting (UK) Ltd | Professional & scientific | 2009 |
| MAY & Philpot Management Limited | Real estate | 1975 |
| MC Carpentry and Plastering Ltd. | Construction | 2017 |
| Mcdaid Designs Limited | Professional & scientific | 2014 |
| Mckenbo Associates Limited | Transport & logistics | 2015 |
| Mcwilcock Limited | Real estate | 2011 |
| MD Personal Limited | Information & communication | 2023 |
| Measured Surveys Ltd | Professional & scientific | 2015 |
| Medella Limited | Health & social care | 2014 |
| Medical Global Trading Ltd | Wholesale & retail | 2011 |
| Medmerry Property Management Ltd | Real estate | 2025 |
| Medmerry Residential Ltd | Real estate | 2025 |
| Melicom Limited | Health & social care | 2014 |
| Mellissa Laycy Ltd. | Other services | 2020 |
| Melos Audio Ltd | Manufacturing | 2016 |
| Membrane Covers Ltd | Manufacturing | 2026 |
| Meon Community Connect CIC | Arts & recreation | 2025 |
| Meon Medico-Legal Ltd | Health & social care | 2017 |
| Meon Springs Limited | Agriculture & fishing | 2012 |
| Meonside Farm Limited | Hospitality | 2024 |
| Mercatans Capital EBT Trustee Limited | Administrative & support | 2021 |
| Mercatans Capital Limited | Financial services | 2018 |
| Mercer General Services Ltd | Construction | 2026 |
| Merchandise Europe Limited | Professional & scientific | 2013 |
| Merepond Lane Services Limited | Professional & scientific | 2025 |
| Merritts Meadow Residents Association Limited | Administrative & support | 2017 |
| Merritt’S of Midhurst Funeral Services Ltd | Other services | 2022 |
| Metal and Butter Limited | Administrative & support | 2008 |
| Metaverse Global Limited | Financial services | 2021 |
| Methos Consulting Limited | Information & communication | 2012 |
| MH Motorsport Limited | Wholesale & retail | 2016 |
| Michael Smith Limited | Administrative & support | 2009 |
| Milani Creations Ltd | Manufacturing | 2024 |
| Mile Digital Limited | Information & communication | 2009 |
| Milkwood Care Ltd | Health & social care | 1999 |
| Millmead Apartments (Oakhill) Management Limited | Households | 1985 |
| Mindmuse Ltd | Administrative & support | 2017 |
| Minimworld Ltd | Information & communication | 2019 |
| Mint Margarita Ltd | Hospitality | 2024 |
| Minted Box Limited | Professional & scientific | 2009 |
| Minty Air Ltd | Transport & logistics | 2025 |
| Miscombe (London) Limited | Real estate | 2015 |
| Miscombe Developments Limited | Construction | 1979 |
| Miscombe Group Limited | Financial services | 1973 |
| Miscombe Limited | Real estate | 1988 |
| Miscombe Property Limited | Professional & scientific | 2015 |
| Miscombe Trading Limited | Professional & scientific | 2015 |
| Miser Hybrid Technologies UK Ltd | Manufacturing | 2015 |
| Miso Sussex Ltd | Hospitality | 2025 |
| MJB Bespoke Property Developments Limited | Construction | 2008 |
| Mlrs Properties Limited | Construction | 2015 |
| Moneybarn Group Limited | Financial services | 2002 |
| Moneybarn Limited | Administrative & support | 1992 |
| Moneybarn NO.1 Limited | Financial services | 2002 |
| Monks Walk (Buriton) Management Company Limited | Households | 2019 |
| Mono Mono Ltd | Information & communication | 2017 |
| Mono Music Management Limited | Information & communication | 2025 |
| Monster Toy Fairs Ltd | Administrative & support | 2025 |
| Montague Bicycles (UK) Ltd | Wholesale & retail | 1995 |
| Montauk Bloodstock Ltd | Agriculture & fishing | 2025 |
| Moore Medical Ltd | Health & social care | 2005 |
| Moorland Views Developments Limited | Construction | 2019 |
| Morgan Innovation & Technology Ltd | Manufacturing | 1987 |
| Morgans Traditional Family Butchers Limited | Wholesale & retail | 2022 |
| Morpheus Commercials Ltd | Wholesale & retail | 2022 |
| Moss Build (South) Limited | Construction | 2020 |
| Motorcycles Only Ltd | Wholesale & retail | 2025 |
| Move Different Community Interest Company | Other services | 2026 |
| Mowbarton Limited | Professional & scientific | 2021 |
| Moxie Business Marketing Ltd | Professional & scientific | 2016 |
| Mtnh Ltd | Real estate | 2020 |
| Mulberry Executive Search Limited | Administrative & support | 2018 |
| Multicomponent Limited | Administrative & support | 2005 |
| Multiscan Surveys Ltd | Professional & scientific | 2026 |
| Muse Beauty Lounge Ltd | Other services | 2025 |
| Music Company (Europe) Limited | Information & communication | 2009 |
| MVP Consulting Ltd | Information & communication | 2024 |
| MWL Golf Limited | Arts & recreation | 2017 |
| My Awesome Life Ltd. | Education | 2018 |
| Myriad Ideation Limited | Professional & scientific | 2014 |
| N a Spice Limited | Hospitality | 2022 |
| N2K Copyrights Ltd | Arts & recreation | 2006 |
| N2K Holdings Limited | Financial services | 2009 |
| N2K Publishing Limited | Information & communication | 2001 |
| N2K Recordings Limited | Information & communication | 2009 |
| Nabscar Limited | Professional & scientific | 2013 |
| Nantlys Flats Management Company Limited | Households | 2022 |
| Ndqs Services Ltd | Professional & scientific | 2019 |
| Ndreams Pool Limited | Financial services | 2023 |
| Neurodiversity Unravelled Ltd | Health & social care | 2018 |
| New Leaf Law Limited | Professional & scientific | 2009 |