| Meridian Spice Medway Ltd | Hospitality | 2023 |
| Meritopusai Ltd | Information & communication | 2026 |
| Merlett Plastics (U.K.) Limited | Wholesale & retail | 1980 |
| Merlin Air Conditioning Limited | Construction | 2011 |
| Merlin Electrical Services Limited | Construction | 1997 |
| Merlin Helix Ltd | Professional & scientific | 2024 |
| Merlin Management 2010 Ltd | Real estate | 2010 |
| Meroestream Ltd | Information & communication | 2021 |
| Meros Productions Limited | Information & communication | 2018 |
| Merrifields Real Estate Ltd | Real estate | 2022 |
| Merryvale Systems Limited | Construction | 2003 |
| Merton Fire and Security Ltd | Administrative & support | 2026 |
| Merunas Ltd | Construction | 2017 |
| Merva Freehold Limited | Real estate | 2023 |
| Merva Ice Creams Limited | Wholesale & retail | 2024 |
| Merva Properties Limited | Real estate | 2022 |
| Mervem LLP | | 2019 |
| Meszaros Trans Ltd | Transport & logistics | 2021 |
| Meta-Morphosis Ltd | Other services | 2024 |
| Metalcare Engineering Limited | Other services | 1994 |
| Metanurse Limited | Health & social care | 2022 |
| Metasim Limited | Information & communication | 2020 |
| Metaveran Limited | Information & communication | 2026 |
| Metcraft Group Ltd | Manufacturing | 2018 |
| Methewsons Limited | Health & social care | 2017 |
| Metric (South East) Group Holdings Ltd | Financial services | 2024 |
| Metric (South East) Holdings Limited | Professional & scientific | 2007 |
| Metric (South East) Ltd | Construction | 2002 |
| Metro Cleaning (South East) Limited | Administrative & support | 2010 |
| Mexican Fusion T/As Tacos Locos Ltd | Hospitality | 2024 |
| Mexigo Kent Ltd | Hospitality | 2020 |
| Mexmarketing Limited | Administrative & support | 2019 |
| MG Mechanical/Electrical Services Limited | Construction | 2020 |
| MG Solutions Services Ltd | Construction | 2021 |
| MG Trans Ltd | Transport & logistics | 2021 |
| MGJ Enforcement Limited | Administrative & support | 2026 |
| MGJ Logistics Limited | Transport & logistics | 2013 |
| MGJ Properties Limited | Real estate | 2006 |
| MGL Healthcare Limited | Health & social care | 2003 |
| MGL Land Surveyors Limited | Professional & scientific | 2016 |
| MH Coms Limited | Information & communication | 2000 |
| MH Facs Ltd | Construction | 2025 |
| MH Wealth Management Ltd. | Financial services | 2014 |
| MHF Consultancy Limited | Professional & scientific | 2023 |
| MHJ Lettings Ltd | Real estate | 2023 |
| Mhrm Consultancy Limited | Administrative & support | 2021 |
| Mhwa Limited | Health & social care | 2012 |
| MI KAS LU Casa Limited | Real estate | 2022 |
| MI Moskalova Ltd | Transport & logistics | 2023 |
| MI10X Ltd | Wholesale & retail | 2019 |
| MIC Construction Ltd | Construction | 2019 |
| MIC Graves Limited | Information & communication | 2008 |
| Michael D Nichols Limited | Professional & scientific | 2015 |
| Michealj's Holdings Limited | Real estate | 2024 |
| Michelle Graham Ltd | Professional & scientific | 2002 |
| Michelle Samuel Consultancy Ltd | Professional & scientific | 2015 |
| Mico Altun Limited | Wholesale & retail | 2018 |
| Micro Precision (North West) Ltd | Wholesale & retail | 1995 |
| Micro Precision (South East) Ltd | Wholesale & retail | 1984 |
| Micro Precision (Wales) Limited | Wholesale & retail | 2002 |
| Microbeau Training Academy Ltd | Other services | 2017 |
| Micu Transport 2015 Limited | Transport & logistics | 2015 |
| MID Electrical Limited | Energy | 2017 |
| MID Kent Aesthetics Ltd | Health & social care | 2018 |
| MID Kent Chimney Sweep Ltd | Administrative & support | 2021 |
| MID Kent Enforcement Ltd | Public administration | 2020 |
| MID Kent Fish & Chips Ltd | Hospitality | 2023 |
| MID Kent Landscaping and Groundworks Ltd | Administrative & support | 2024 |
| MID Kent Orthodontics Limited | Health & social care | 2016 |
| Midas Finance Group Ltd | Wholesale & retail | 2012 |
| Midas Properties (UK) Limited | Real estate | 2000 |
| Midas Waste Management Limited | Water & waste | 2018 |
| Middleleaze Ventures Ltd | Financial services | 2023 |
| Midkent Cleaning Limited | Administrative & support | 2020 |
| Migrant Empowerment & Support Hub CIC | Professional & scientific | 2026 |
| Migrate Art CIC | Wholesale & retail | 2019 |
| MIH Consultancy Limited | Administrative & support | 2012 |
| Miirinzo Limited | Construction | 2018 |
| MIJ Logistics Ltd | Wholesale & retail | 2022 |
| Mika Racing Ltd | Real estate | 2023 |
| Mikael Private Ltd | Hospitality | 2024 |
| Mike Owen Ltd | Agriculture & fishing | 2008 |
| Mike Palmer Sound Limited | Information & communication | 2014 |
| Mikesteph Consultants Limited | Information & communication | 2024 |
| Milbug Group Ltd | Real estate | 2023 |
| Milch London Ltd | Administrative & support | 2006 |
| Mildview Limited | Real estate | 1999 |
| Mill House Property Services Limited | Construction | 2015 |
| Millaber Holdings Limited | Extraterritorial | 2001 |
| Millbrae Investments Ltd | Construction | 2011 |
| Millbrook BMS Limited | Construction | 2020 |
| Millburn Properties Limited | Real estate | 1997 |
| Millennium Integrated Services Ltd. | Information & communication | 1998 |
| Miller Brothers Services Limited | Construction | 2019 |
| Miller Food and Wine Ltd | Wholesale & retail | 2020 |
| Millfield Homes Limited | Construction | 2019 |
| Millhill Properties (Guildford) UK Limited | Real estate | 2022 |
| Millhouse Medway Ltd | Administrative & support | 2025 |
| Millington Building Services Ltd | Construction | 2023 |
| Mills Property Holdings Limited | Real estate | 2018 |