| Mehta Family Estates Limited | Financial services | 2021 |
| Mehta Traders Ltd | Wholesale & retail | 2025 |
| Meif II - Smaller Loans WM LP | | 2024 |
| Meif WM Small Business Loans LP | | 2017 |
| Meji Media Ltd | Arts & recreation | 2006 |
| Meji Technology Limited | Information & communication | 2021 |
| Melanin Moods C.I.C. | Education | 2023 |
| Melanin Plus Limited | Manufacturing | 2019 |
| Melbourne Consultants Limited | Wholesale & retail | 2015 |
| Melbury Motor Market Ltd | Wholesale & retail | 2022 |
| Melds Healthcare Services Ltd | Health & social care | 2022 |
| Melgel Care Limited | Health & social care | 2015 |
| Mellvad Riches Ltd | Transport & logistics | 2022 |
| Melsious Ltd | Administrative & support | 2024 |
| Melsom Fire Safety Consultancy Limited | Extraterritorial | 2025 |
| Melt Theory Ltd | Manufacturing | 2026 |
| Meltdown Cookies Limited | Wholesale & retail | 2025 |
| Melting Icecubes Ltd | Information & communication | 2018 |
| Mely Contractors Ltd | Construction | 2022 |
| MEM Multi Services Ltd | Administrative & support | 2025 |
| Memar Investments Limited | Real estate | 2020 |
| Membracon (UK) Limited | Manufacturing | 2002 |
| Membracon UK Holdings Limited | Other services | 2017 |
| Menaramold Ltd | Information & communication | 2026 |
| Menc & Co Property Ltd | Real estate | 2016 |
| Mencap Wolverhampton | Health & social care | 1988 |
| Meneanor Ltd | Transport & logistics | 2019 |
| Meno Trans Limited | Transport & logistics | 2024 |
| Mensa Limited | Extraterritorial | 2019 |
| Mensa Publications Limited | Information & communication | 1989 |
| Mental Health (Midlands) CIC | Health & social care | 2019 |
| Mentalisimo Ltd | Education | 2022 |
| MEO Properties Limited | Hospitality | 2007 |
| Meqwa Ltd | Wholesale & retail | 2026 |
| Mera Panjab Ltd | Wholesale & retail | 2025 |
| Mera PANJAB13 Ltd | Transport & logistics | 2025 |
| Meraco Ltd | Education | 2025 |
| Meraj Ahmed Siddique Ltd | Wholesale & retail | 2025 |
| Mercantile Claims Management Solutions Limited | Administrative & support | 2016 |
| Merchvanta Ltd | Wholesale & retail | 2024 |
| Mercia Automation Services Limited | Manufacturing | 1999 |
| Mercia Financial Limited | Financial services | 2026 |
| Mercia QA Limited | Administrative & support | 2006 |
| Meredith Medical Services Ltd | Health & social care | 2016 |
| Meridale Care Services Ltd | Health & social care | 2023 |
| Meridale Properties Ltd | Real estate | 2023 |
| Meridale Recruiting Solutions Ltd | Administrative & support | 2019 |
| Meridale Store Ltd | Wholesale & retail | 2018 |
| Meridian Health & Social Care Limited | Health & social care | 2007 |
| Meridian Legal Services Limited | Administrative & support | 2014 |
| Meritgates Investment Ltd | Real estate | 2023 |
| Merlin Accountants Limited | Professional & scientific | 2012 |
| Merlin Financial Services Worcester LLP | | 2008 |
| Merlin Master FRY Ltd | Hospitality | 2024 |
| Merlins Group Limited | Information & communication | 2025 |
| Merridale Group Limited | Hospitality | 2017 |
| Merridale Ltd | Manufacturing | 1994 |
| Merridale Polishing and Plating Company Limited | Administrative & support | 1974 |
| Mers INS Limited | Financial services | 2010 |
| Merthyr Cuts Limited | Other services | 2024 |
| Merthyr Vale Ltd | Administrative & support | 2021 |
| Merxpert Ltd | Information & communication | 2026 |
| Mes-Bre Ltd | Real estate | 2025 |
| Mesolean Group Ltd. | Professional & scientific | 2016 |
| Message Jane Limited | Real estate | 2025 |
| Metal Polishing Cooperative Limited | Manufacturing | 1986 |
| Metal RAM Ltd | Wholesale & retail | 2025 |
| Metal Roofing and Cladding Limited | Manufacturing | 2017 |
| Metalux Bullion Ltd | Wholesale & retail | 2023 |
| Metaverse Recruitment Limited | Information & communication | 2017 |
| Metelec Limited | Wholesale & retail | 2002 |
| Meteore Retail Ltd | Wholesale & retail | 2025 |
| Meteoroid Solutions Ltd | Professional & scientific | 2019 |
| Metrico Fans (UK) Ltd | Manufacturing | 2006 |
| Metro Business Partnership Limited | Other services | 2006 |
| Metropolitan and Westcliff Property Company Limited | Construction | 1960 |
| Metropolitan and Westcliff Property Management Limited | Real estate | 2004 |
| Metzpro Ltd | Manufacturing | 2004 |
| Meye Optical Ltd | Wholesale & retail | 2023 |
| Meyrick Builders & Roofers Ltd | Construction | 2019 |
| Mezvynia Ltd | Wholesale & retail | 2021 |
| Mezystores Ltd | Wholesale & retail | 2024 |
| Mezzo Dance Ltd | Education | 2025 |
| MF Business Ltd | Hospitality | 2022 |
| MF Greenhouses Ltd | Real estate | 2024 |
| MF Installations and Facilities Management Ltd | Construction | 2025 |
| MF Tykon Ltd | Wholesale & retail | 2024 |
| Mflav Consult Ltd | Professional & scientific | 2020 |
| Mflr Properties Limited | Real estate | 2024 |
| MG Accident Repair Centre Ltd | Wholesale & retail | 2022 |
| MG Electrical Installations Limited | Construction | 2016 |
| MG Powerbuild Ltd | Construction | 2026 |
| MG Roofing Limited | Construction | 2018 |
| MG V8 Parts Limited | Wholesale & retail | 2009 |
| MGH Courier Ltd | Transport & logistics | 2024 |
| Mgill Properties Limited | Real estate | 2024 |
| MGM Digital Ltd | Professional & scientific | 2018 |
| MGM Rentals Ltd | Real estate | 2024 |
| MGR Couriers Ltd | Transport & logistics | 2022 |
| MGT Agricultural Solutions Limited | Administrative & support | 2010 |