| M'Arks of SE8 Limited | Hospitality | 2019 |
| M. & R. Hartman Limited | Administrative & support | 2010 |
| M.A.C. Welding Limited | Construction | 2012 |
| M.C Heating & Plumbing Ltd | Construction | 2023 |
| Mackinnon Property Consultants (MPC) Ltd | Arts & recreation | 2014 |
| Madame Modiste Ltd | Professional & scientific | 2021 |
| Maeva RAE Ltd | Wholesale & retail | 2021 |
| Magnolia Court (Whitstable) Property Company Limited | Households | 1984 |
| Maidstone Buy to LET Limited | Real estate | 2025 |
| Majar Aviation Consultant Limited | Administrative & support | 2011 |
| Makalla Mcpherson Ltd | Information & communication | 2021 |
| Make IT Stick Ltd | Professional & scientific | 2022 |
| Maltings Management Co. (Abbey Street) Limited(The) | Households | 1983 |
| Mamasoothe Ltd | Wholesale & retail | 2025 |
| Management 75 Limited | Construction | 2012 |
| Manere Ltd | Real estate | 2019 |
| Manor Care Homes Ltd | Health & social care | 2000 |
| Manor Mews (Old Woking) Property Management Limited | Real estate | 2018 |
| Manston Fabrication Ltd | Manufacturing | 2024 |
| Maple Leaf Hair Limited | Other services | 2022 |
| Mappy’S Catering Services Ltd | Hospitality | 2024 |
| Marble Financial Planning Ltd | Administrative & support | 2013 |
| Marbleson Ltd | Education | 2013 |
| Marchant Construction Limited | Wholesale & retail | 1995 |
| Marcus James (Kent) Limited | Manufacturing | 2025 |
| Mareporta Property Management CIC | Real estate | 2017 |
| Margo Selby Artist Limited | Arts & recreation | 2023 |
| Margo Selby Limited | Manufacturing | 2007 |
| Marie Antoinette Company (the) Limited | Professional & scientific | 1927 |
| Mariette Limited | Extraterritorial | 1964 |
| Marine Accounts Consultancy Limited | Financial services | 2018 |
| Marine Accounts Ltd | Professional & scientific | 2014 |
| Marine Mortgages Ltd | Financial services | 2016 |
| Marine View Developments Ltd | Real estate | 2023 |
| Mariners LEE Management Company Limited | Households | 2001 |
| Maritime Kitchens Ltd | Wholesale & retail | 2026 |
| Marjasprop Limited | Households | 2007 |
| Mark Terrell Art & SMP Ltd | Education | 2026 |
| Marlowe Court Limited | Households | 1987 |
| Marnie MAE Boutique Limited | Wholesale & retail | 2026 |
| Martec Limited | Manufacturing | 1987 |
| Martin Epps Property Management Ltd | Real estate | 2014 |
| Martin Mayall Holdings Ltd | Financial services | 2025 |
| Martin Mayall Ltd | Health & social care | 2015 |
| Martin Neville Boiler Services Limited | Administrative & support | 2010 |
| Martin Warman Consultancy Limited | Professional & scientific | 2007 |
| Massimo London Ltd | Manufacturing | 2016 |
| Masterfish Ltd. | Agriculture & fishing | 2011 |
| Mathew and Redsell Limited | Administrative & support | 2009 |
| Mathmagicians Ltd | Education | 2024 |
| Matmil Limited | Information & communication | 2012 |
| Matt Thomas Enterprises Ltd | Professional & scientific | 2015 |
| Mattamore Ltd | Professional & scientific | 2026 |
| Matthews Family Investment Limited | Financial services | 2022 |
| Matthews Investment Lettings Limited | Real estate | 2014 |
| Matthews&Taylor Ltd | Construction | 2016 |
| Mattressnextday Limited | Wholesale & retail | 2005 |
| Maugham Court Property Association Limited | Real estate | 1971 |
| Maunsell International School Ltd | Education | 2022 |
| Mavrk Media Ltd | Manufacturing | 2017 |
| Maxxed OUT Events Ltd | Arts & recreation | 2026 |
| Mayarc Ltd | Manufacturing | 2022 |
| Mayday Plumbing (Whitstable) Limited | Administrative & support | 2001 |
| Maytree Mortgages Ltd | Financial services | 2014 |
| Mazoom IT Limited | Information & communication | 2007 |
| Mazuco Limited | Health & social care | 2025 |
| MC Creative Management Ltd | Administrative & support | 2022 |
| MC Golf Promotions Limited | Arts & recreation | 2022 |
| Mcdonnell Customer Experience Ltd | Professional & scientific | 2026 |
| Mclean & Mclean Limited | Professional & scientific | 2021 |
| Meadow Foot Care Ltd | Health & social care | 2022 |
| Meadow Grange Nursery Limited | Agriculture & fishing | 2019 |
| Meantime Holdings Limited | Professional & scientific | 2019 |
| Mechanical and Technical Services Ltd | Manufacturing | 2023 |
| Media Coach International Ltd | Professional & scientific | 2008 |
| Medical Case Notes Assessment Limited | Health & social care | 2003 |
| Medimove Ambulance Service Limited | Transport & logistics | 2024 |
| Mednovae Ltd | Manufacturing | 2025 |
| Medviro UK Limited | Administrative & support | 2026 |
| Medway Container Storage Ltd | Administrative & support | 2022 |
| Medway Court Management Limited | Households | 2010 |
| Megson Construction and Property Maintenance Ltd | Construction | 2019 |
| Melted Rock Ltd | Wholesale & retail | 2014 |
| Merchant Private Finance Ltd | Financial services | 2011 |
| Merchant Real Estate Ltd | Real estate | 2018 |
| Merdale Fruits Ltd | Agriculture & fishing | 2010 |
| Meridian Expat Mortgages Ltd | Financial services | 2019 |
| Meridian Maintenance (Kent) Limited | Construction | 2020 |
| Mesec Ltd | Administrative & support | 2021 |
| Metafrica Ltd | Information & communication | 2025 |
| Method & Mortar Ltd | Construction | 2026 |
| Mettyear's Day Spa & Salon Ltd | Other services | 2016 |
| Mettyear-Rowe Ltd | Other services | 2024 |
| Mettyears Academy Ltd | Other services | 2024 |
| Mewett Polyurethane Ltd | Manufacturing | 1973 |
| MGH Building and Landscaping Limited | Construction | 2024 |
| Mgoreilly Assessment Services Limited | Education | 2018 |
| MGP Tech Ltd | Other services | 2021 |
| MGW Enforcement Limited | Administrative & support | 2025 |
| MHC Mortgage & Protection Ltd | Financial services | 2019 |