| Memon Medical Services Limited | Other services | 2022 |
| Memorial Benches UK Ltd | Wholesale & retail | 2014 |
| Memsa London Ltd | Wholesale & retail | 2025 |
| Memsaab Properties Limited | Real estate | 2002 |
| Mendip Media Group Ltd. | Information & communication | 1993 |
| Mentor Accounting Services Ltd | Professional & scientific | 2015 |
| Mentor Board College Ltd. | Information & communication | 2018 |
| Menza Ltd | Wholesale & retail | 2018 |
| MEP Fire Detection Ltd | Construction | 2024 |
| MEP Fire Passive Protection Ltd | Construction | 2024 |
| MEP Fire Suppression Ltd | Manufacturing | 2019 |
| MEP Stock Ltd | Wholesale & retail | 2017 |
| Merak Consultants Ltd | Professional & scientific | 2023 |
| Meraze Limited | Manufacturing | 2011 |
| Merce Inn Ltd | Wholesale & retail | 2024 |
| Merchandise Pro Ltd | Wholesale & retail | 2025 |
| Merchhaven Limited | Wholesale & retail | 2025 |
| Mercury Property Group Ltd | Real estate | 2026 |
| Mercy MED Services Ltd | Health & social care | 2014 |
| Mercytech Limited | Professional & scientific | 2005 |
| Merdo Ltd | Other services | 2020 |
| Meri Sehat Limited | Health & social care | 2014 |
| Meridian Executive Limited | Transport & logistics | 2007 |
| Meridian Freight Services Limited | Transport & logistics | 1982 |
| Meridian Insight Ltd | Professional & scientific | 2011 |
| Merido Ltd | Financial services | 2025 |
| Merigold CIC | Hospitality | 2026 |
| Merrington Road Management Limited | Households | 1995 |
| Merrivale Care & Allied Services Ltd | Administrative & support | 2021 |
| Merry Holidays Ltd | Administrative & support | 2013 |
| Meru Change Partners Ltd | Professional & scientific | 2025 |
| Meru Finance Ltd | Financial services | 2026 |
| MESSENGER2050 Technologies UK Limited | Information & communication | 2022 |
| Meta Extended Reality Ltd | Manufacturing | 2022 |
| Meta Invictus Limited | Information & communication | 2022 |
| Metal Window Renovations Limited | Construction | 1992 |
| Metaverse Digital Ltd | Mining & quarrying | 2021 |
| Meterit Utilities Ltd | Construction | 2018 |
| Method Management Limited | Professional & scientific | 2021 |
| Meticulous Properties Ltd | Real estate | 2023 |
| Metro Bandit Limited | Information & communication | 2021 |
| Metro Builders & Driveways Limited | Construction | 2023 |
| Metro Car Service Ltd | Transport & logistics | 2025 |
| Metro Courier Service Limited | Transport & logistics | 2015 |
| Metro Holdings Group (UK) Ltd | Real estate | 2020 |
| Metropole Guard Security Ltd | Administrative & support | 2020 |
| Mexborough Practice Limited | Health & social care | 2022 |
| Mexil Industrial Solutions Ltd | Wholesale & retail | 2024 |
| Mextemps Ltd | Administrative & support | 2012 |
| Mezabi Ltd. | Information & communication | 2023 |
| Mezan Chambers Ltd | Other services | 2013 |
| MF Blinds Limited | Wholesale & retail | 2025 |
| MFI Lillesden 1 Ltd | Real estate | 2025 |
| MFI Lillesden 2 Ltd | Real estate | 2025 |
| MFT Partners Ltd | Professional & scientific | 2022 |
| MG Law Ltd | Other services | 2020 |
| MG Management Solutions Ltd | Administrative & support | 2017 |
| MG Pro Ltd | Real estate | 2024 |
| Mgek Consortium Group Ltd | Professional & scientific | 2024 |
| MGI Croydon Limited | Real estate | 2024 |
| MGK Infra Realty Ltd | Construction | 2022 |
| MGK Real Estates Ltd | Construction | 2022 |
| MGMD2 Limited | Real estate | 2026 |
| Mgmt Collective Limited | Professional & scientific | 2025 |
| Mgpg Holdings Ltd | Real estate | 2025 |
| Mgrusu Ltd | Transport & logistics | 2019 |
| Mgvd Property Limited | Real estate | 2024 |
| MH Diagnostics Limited | Health & social care | 2022 |
| MH Epic Ltd | Real estate | 2021 |
| MH Petroleum Services Ltd | Wholesale & retail | 2025 |
| MH Property and Lettings Ltd | Real estate | 2025 |
| MH Sales & Growth Consulting Limited | Professional & scientific | 2025 |
| MH1 Construction Limited | Construction | 2016 |
| MH46 Limited | Transport & logistics | 2025 |
| MHA Global Equipment Ltd | Wholesale & retail | 2026 |
| MHA Global Trade Ltd | Real estate | 2024 |
| MHA Home Ltd | Real estate | 2026 |
| MHA Wellness Ltd | Wholesale & retail | 2024 |
| MHJ Global Ltd | Real estate | 2025 |
| MHM Couriers Services Ltd | Transport & logistics | 2023 |
| MHQ Services Ltd | Administrative & support | 2026 |
| Mhungu Limited | Transport & logistics | 2015 |
| MI Consulting House Ltd | Information & communication | 2021 |
| MI IT Services Ltd | Extraterritorial | 2017 |
| Mi.Cbh Ltd | Wholesale & retail | 2024 |
| MIA Chai Ltd | Hospitality | 2023 |
| Miami Whippy Limited | Manufacturing | 2026 |
| Mian Exports Ltd | Wholesale & retail | 2025 |
| Mian Travel Ltd | Administrative & support | 2019 |
| Mian's Trading UK Limited | Transport & logistics | 2021 |
| Mice’S Transport Ltd | Transport & logistics | 2018 |
| Michaelwealth Limited | Administrative & support | 2019 |
| Michal Bogacki Transport Limited | Transport & logistics | 2017 |
| Michella Estates Limited | Real estate | 2022 |
| Michjov Care Ltd | Health & social care | 2025 |
| Mick Shoard Ltd | Real estate | 2026 |
| Mickybros Construction Limited | Construction | 2019 |
| Mickybros Driveways and Landscaping Ltd | Construction | 2025 |
| Microhard Holdings Limited | Real estate | 2001 |
| Microservices Ltd | Information & communication | 2018 |