| Mckennaburge Ltd | Real estate | 2024 |
| MCM Properties & Lettings Ltd | Real estate | 2024 |
| Mcmurtry Ltd. | Construction | 1995 |
| Mcnallys Property Development Limited | Construction | 2015 |
| Mcnathan Property Limited | Real estate | 2022 |
| Mcrae Hvac Ltd | Energy | 2023 |
| MD Ball Limited | Construction | 2018 |
| MD Carpentry and Joinery Ltd | Manufacturing | 2016 |
| MD1 Technology Holdings Limited | Financial services | 2026 |
| MDE Electrical Limited | Construction | 2017 |
| MDJ Capital Ltd | Manufacturing | 2025 |
| MDJ Electrical Ltd | Construction | 2005 |
| MDP Electrical Controls Limited | Construction | 2009 |
| ME (South West) Ltd | Construction | 2024 |
| MEA Scanning Ltd | Construction | 2024 |
| Meadow Street Management Limited | Households | 2009 |
| Meadows Wealth Management Limited | Professional & scientific | 2016 |
| Meah Homes Ltd | Real estate | 2024 |
| Mealing and Company Limited | Professional & scientific | 1994 |
| Mears Energy Limited | Extraterritorial | 2004 |
| Mears Estates Limited | Professional & scientific | 1999 |
| Mears Extra Care Limited | Financial services | 1998 |
| Mears Facility Management Limited | Professional & scientific | 2001 |
| Mears Group PLC | Financial services | 1996 |
| Mears Homes Limited | Extraterritorial | 2000 |
| Mears Housing Management (Holdings) Limited | Professional & scientific | 2003 |
| Mears Housing Management Limited | Real estate | 1998 |
| Mears Limited | Administrative & support | 1990 |
| Mears New Homes Limited | Construction | 2013 |
| Mears Social Housing Limited | Extraterritorial | 2003 |
| Mears Wales Limited | Extraterritorial | 2004 |
| MEB Solvo Limited | Transport & logistics | 2022 |
| MEB Total Holdings Limited | Financial services | 2026 |
| Mecamora Holding Ltd | Administrative & support | 2010 |
| Mecasphere Solutions Ltd | Information & communication | 2025 |
| Mecelec Design Holdings Limited | Financial services | 2025 |
| Mechanical Installation Heating Services (Glos) Limited | Construction | 1988 |
| Mechanical Installation Heating Services Limited | Financial services | 2018 |
| Mechatronical Ltd | Manufacturing | 2020 |
| Meddigital Limited | Information & communication | 2007 |
| Mediadog Digital Ltd | Professional & scientific | 2014 |
| Mediation in Planning Limited | Professional & scientific | 2007 |
| Medisale Limited | Wholesale & retail | 2017 |
| Medpros INT Ltd | Information & communication | 2025 |
| Medrex Limited | Professional & scientific | 2012 |
| Medsante Wellness Limited | Professional & scientific | 2013 |
| Medusa CPD Limited | Education | 2025 |
| Medynska Press Ltd | Wholesale & retail | 2026 |
| Meeting Booked Limited | Financial services | 2026 |
| Mega Merch Branding Ltd | Manufacturing | 2009 |
| Mega Sourcing and Merchandising Limited | Wholesale & retail | 2020 |
| Meganaut Ltd | Information & communication | 2017 |
| MEL Group Ltd | Hospitality | 2025 |
| Melazza Ltd | Wholesale & retail | 2021 |
| Melford Environmental Services Limited | Other services | 1999 |
| Meli-Melo Event Catering Ltd | Hospitality | 2023 |
| Melk Holdings Limited | Financial services | 2023 |
| Melvin Bath & Co Legal Services Ltd | Information & communication | 2013 |
| Memc Consultancy Ltd | Information & communication | 2022 |
| Men's Health Engineers Ltd | Health & social care | 2024 |
| Mental Mutt Ltd | Wholesale & retail | 2021 |
| MEO Brothers Limited | Hospitality | 2024 |
| Merbro Welding Ltd | Extraterritorial | 2012 |
| Mercer Property Limited | Real estate | 2012 |
| Merge IT Limited | Information & communication | 2019 |
| Meridian Foods Limited | Manufacturing | 2005 |
| Merlin Construction (Stroud) Limited | Construction | 2021 |
| Merlon Consulting Limited | Professional & scientific | 2012 |
| Merretts Taxis Ltd | Transport & logistics | 2006 |
| Merrick Cardew Group Ltd | Financial services | 2026 |
| Merrick Fencing Limited | Construction | 2026 |
| Merriman Roofing Contractors Limited | Construction | 2011 |
| Merrydown PLC | Manufacturing | 1946 |
| Merryfield Electrical Contractors Limited | Construction | 2024 |
| Meryline Ltd | Administrative & support | 2025 |
| Mesnards Ltd | Professional & scientific | 2026 |
| Metalcashcard Limited | Administrative & support | 2012 |
| Meteor Court Management Limited | Real estate | 2019 |
| Methodist Insurance Public Limited Company | Financial services | 1872 |
| Methodist Insurance Services Limited | Extraterritorial | 2011 |
| Metro Facilities Management Ltd | Construction | 2021 |
| Metropolis Garages Limited | Construction | 2008 |
| MEV KIT Cars Ltd | Manufacturing | 2026 |
| Mewp Innovations Ltd | Manufacturing | 2017 |
| Mezuzah Store Limited | Manufacturing | 2026 |
| MG Electrical (Glos) Ltd | Construction | 2025 |
| MG Markey Group Limited | Real estate | 1991 |
| MG Markey Holdings Limited | Real estate | 2015 |
| MG Travel (Gloucester) Ltd | Transport & logistics | 2022 |
| MGUN1987 Ltd | Hospitality | 2017 |
| MH & N Properties Ltd | Real estate | 2025 |
| MH Electrical (SW) Ltd | Manufacturing | 2011 |
| MH Inns Ltd | Hospitality | 2021 |
| MHB Transport (Glos) Ltd | Transport & logistics | 2018 |
| MHP Property (Bristol) Limited | Real estate | 2024 |
| MHS Health Solutions Ltd | Health & social care | 2025 |
| MHS Plumbing & Heating Limited | Construction | 2016 |
| MIA Luckie Ltd | Professional & scientific | 2021 |
| Michael Smith Motors Ltd | Wholesale & retail | 2003 |
| Michael Tuck Lettings Limited | Real estate | 1999 |