| MD Development Limited | Administrative & support | 2024 |
| MD Tutors Limited | Education | 2025 |
| MDG Maintenance Ltd | Construction | 2023 |
| MDI Associates Ltd. | Administrative & support | 2001 |
| Mdic Limited | Financial services | 2022 |
| MDP Recruitment Limited | Other services | 2020 |
| MDS Essex Ltd | Wholesale & retail | 2019 |
| Mdsz Consultancy Ltd | Professional & scientific | 2014 |
| Mdsz Holdings Ltd | Real estate | 2018 |
| MDT Coaching and Consulting Ltd | Professional & scientific | 2016 |
| MDT Properties Services Ltd | Real estate | 2023 |
| Mead News Ltd | Wholesale & retail | 2022 |
| Mealstation Ltd | Construction | 2025 |
| Media of Muse Ltd | Information & communication | 2019 |
| Media Works Network Ltd | Information & communication | 2025 |
| Mediashare Ltd | Administrative & support | 2007 |
| Medical Aims Ltd | Health & social care | 2023 |
| Medical Physics Consultancy Ltd | Professional & scientific | 2023 |
| Medichoice Healthcare Partnership | | 2003 |
| Medichoice Limited | Extraterritorial | 2006 |
| Medicsupport Limited | Health & social care | 2022 |
| Medidorm Limited | Health & social care | 2021 |
| Medis Pharma Ltd | Wholesale & retail | 2023 |
| Medite Smartply UK Limited | Administrative & support | 2008 |
| Meditech Associates Limited | Information & communication | 2014 |
| Medlux Services Limited | Health & social care | 2018 |
| Medo Foods Ltd | Wholesale & retail | 2011 |
| Medpro Ltd | Health & social care | 2008 |
| Medrealty Limited | Real estate | 2025 |
| Medway City Property Company Limited | Real estate | 2010 |
| Medway Escalator Services Limited | Construction | 2002 |
| Medway Glass & Glazing Limited | Construction | 2026 |
| Medway Plastering Co. Limited | Construction | 1985 |
| Medway Plumbing & Heating Ltd | Construction | 2024 |
| Meem Estates Limited | Real estate | 2022 |
| Meeson Electrical Ltd | Construction | 2025 |
| MEF Lift Consultancy Limited | Professional & scientific | 2023 |
| MEGA-21 Ltd | Hospitality | 2018 |
| Megabyte Electrical Engineering Services Ltd | Professional & scientific | 2025 |
| Meggy MOO Kids Care Ltd | Wholesale & retail | 2015 |
| Mehmet Construction Ltd | Construction | 2019 |
| Mehmet Holdings Ltd | Real estate | 2019 |
| Mehnat Limited | Real estate | 2016 |
| MEJ Cleaning Ltd | Other services | 2018 |
| Mekhea Ltd | Health & social care | 2022 |
| Mekx Ltd | Professional & scientific | 2014 |
| Mela Laundrette Limited | Other services | 2017 |
| Melbond (Crossways) Limited | Construction | 2014 |
| Melbond (Maintenance) Limited | Construction | 2015 |
| Melbond Lettings Ltd | Other services | 2016 |
| Melbond Properties Limited | Construction | 2002 |
| Melbury Financial Ltd | Financial services | 2012 |
| Melrose Brown Limited | Real estate | 2018 |
| Menage Wealth and Financial Services Limited | Financial services | 2026 |
| Mendl & Mendl Roofing Limited | Construction | 2024 |
| Meni's Cars Ltd | Wholesale & retail | 2021 |
| Mentra Support Technologies Ltd | Information & communication | 2026 |
| Meraki Art Studio Ltd | Professional & scientific | 2024 |
| Meraki Hair Studio Ltd | Other services | 2019 |
| Mercer Fire Electrical Ltd | Construction | 2025 |
| Merchant Games Ltd. | Information & communication | 2016 |
| Mercified Limited | Professional & scientific | 2026 |
| Mercy Field Limited | Real estate | 2023 |
| Meregate Property Limited | Financial services | 2024 |
| Meridian VP Football Club Ltd | Arts & recreation | 2006 |
| Meridianx Ltd | Information & communication | 2020 |
| Merk Ltd | Construction | 2018 |
| Metal Prefabrications (Dartford) Limited | Manufacturing | 1958 |
| Metalloyd Limited | Financial services | 2025 |
| Metcalfe Briggs Ltd | Professional & scientific | 2013 |
| Methuen Road Freehold Company Ltd | Real estate | 2019 |
| Metro Design Consultants Ltd | Professional & scientific | 2009 |
| Metro Heating & Air Conditioning Services Limited | Construction | 1983 |
| Metroinns (Suffolk) Limited | Hospitality | 2011 |
| Metropolitan Recovery Ltd | Wholesale & retail | 2005 |
| Mexco UK Limited | Professional & scientific | 2005 |
| MF Consultancy Services Ltd | Information & communication | 2017 |
| MFB Construction Ltd | Construction | 2014 |
| MFX Relocation Lease Limited | Other services | 2021 |
| MFX Systems Limited | Information & communication | 2012 |
| MG3D Limited | Other services | 2015 |
| MGB Sparky Ltd | Construction | 2023 |
| Mggm Consulting Ltd | Professional & scientific | 2010 |
| Mggm Homes Ltd | Real estate | 2024 |
| MGL Global Investments Ltd | Financial services | 2023 |
| MGM Movement Ltd | Arts & recreation | 2025 |
| Mgts Construction Ltd | Construction | 2025 |
| MI Kebab Ltd | Hospitality | 2021 |
| Mi.Ee Consulting LLP | | 2021 |
| Micbex Engineering Limited | Manufacturing | 2004 |
| Micdesign Ltd | Wholesale & retail | 2024 |
| Michael Coins Limited | Wholesale & retail | 2014 |
| Michael Isaiah Private Office Ltd | Professional & scientific | 2025 |
| Michael Simpson Studio Ltd | Arts & recreation | 2023 |
| Michelles Kitchen Ltd | Hospitality | 2025 |
| Microfix Limited | Administrative & support | 2009 |
| Microfix Office Services Limited | Extraterritorial | 2009 |
| Micu Limited | Transport & logistics | 2026 |
| MID Blue International Limited | Information & communication | 1988 |
| MID Kent Commercials Ltd | Wholesale & retail | 2019 |