| Maptec Holdings Limited | Professional & scientific | 2021 |
| Maptec Surveys Limited | Professional & scientific | 2017 |
| Marco's Own Limited | Manufacturing | 2016 |
| Mardan Group Limited | Financial services | 2022 |
| Mardan Removals and Storage Ltd | Transport & logistics | 2014 |
| Maria Essential Care Limited | Administrative & support | 2016 |
| Marineminds Ltd | Professional & scientific | 2024 |
| Maritime Design Projects Limited | Administrative & support | 2008 |
| Mark 1 Plumbing & Heating Ltd | Construction | 2016 |
| Mark Brickley Property Holdings Ltd | Real estate | 2017 |
| Mark One Consultants Limited | Information & communication | 1998 |
| Marlls Ltd | Hospitality | 2025 |
| Marrow Hospitality Ltd | Hospitality | 2025 |
| Marsh Farm Free Range Limited | Agriculture & fishing | 2017 |
| Martha’S Stones Ltd | Information & communication | 2025 |
| Martin S. LEE Associates Limited | Administrative & support | 2011 |
| Marybam Ltd | Health & social care | 2021 |
| Masp Consultancy Ltd | Information & communication | 2025 |
| Massala Express Limited | Hospitality | 2019 |
| Massala Takeout Limited | Hospitality | 2026 |
| Masters Tech Group Ltd | Information & communication | 2026 |
| Materials Engineering Services Ltd | Professional & scientific | 2025 |
| Materials Science Solutions Limited | Professional & scientific | 2017 |
| Matt Flint Limited | Arts & recreation | 2025 |
| Matt FOX Limited | Construction | 2018 |
| Matthew J Weallans Electrical Ltd | Construction | 2024 |
| Matthew J Weallans Electrical Services Ltd | Construction | 2024 |
| Maximum Effect UK Ltd | Professional & scientific | 2006 |
| Mayflower Hydraulics Limited | Professional & scientific | 1980 |
| MB Eternal Trading Limited | Information & communication | 2022 |
| Mbsd Ltd | Real estate | 2019 |
| MBU Healthcare UK Ltd | Health & social care | 2015 |
| MC Enterprises Dorset Ltd | Hospitality | 2025 |
| Mcgill’S Construction Limited | Construction | 2017 |
| Mcqueen Television Limited | Other services | 1995 |
| MCS Supported Employment Ltd | Administrative & support | 2023 |
| MDS Developments Ltd | Construction | 2025 |
| Medagam H&S Healthcare Ltd | Health & social care | 2022 |
| Medagam H&S Real Estates Ltd | Real estate | 2022 |
| Media Group Europe Limited | Information & communication | 2017 |
| Medical Indemnity Consultants Limited | Extraterritorial | 2015 |
| Medical Insurance Consultants Ltd. | Administrative & support | 1997 |
| Medicare Excellence Limited | Health & social care | 2022 |
| Medprop Group Ltd | Professional & scientific | 2023 |
| Meed International Limited | Construction | 2022 |
| Meet at Eight Ltd | Hospitality | 2023 |
| Mercers Offshore (Holdco) Limited | Administrative & support | 2026 |
| Mercers Offshore Limited | Administrative & support | 2010 |
| Merryfield International Ltd | Real estate | 2019 |
| Messrs Snook Ltd | Agriculture & fishing | 2006 |
| Metro Kitchen Ltd | Hospitality | 2021 |
| Metro Supermarket Ltd | Wholesale & retail | 2020 |
| MGM 2022 Ltd | Health & social care | 2026 |
| MHFA4ALL Limited | Education | 2024 |
| MHR Projects Limited | Professional & scientific | 2015 |
| MIC Holdings Limited | Extraterritorial | 2002 |
| Michael Pitman Limited | Construction | 2010 |
| Micron Communications Limited | Information & communication | 1998 |
| Midshire Properties Ltd | Real estate | 2009 |
| Midwest Consulting Limited | Professional & scientific | 2002 |
| Mike Loveless & Sons Limited | Administrative & support | 1960 |
| Mike Neville Limited | Construction | 2015 |
| Mikrobio Ltd | Information & communication | 2024 |
| Mikucki Steel Detailing Ltd | Professional & scientific | 2019 |
| Millbrook Management Company (Yeovil) Limited | Households | 2017 |
| Mindshare Creative Ltd | Professional & scientific | 2019 |
| Mineral Bases Limited | Extraterritorial | 2017 |
| Mineral Heritage Limited | Mining & quarrying | 2019 |
| Miuz Ltd | Information & communication | 2025 |
| MIZ Ltd | Wholesale & retail | 2019 |
| Mizuplumbingandheating Limited | Construction | 2025 |
| MJ Aesthetic Medical Ltd | Health & social care | 2025 |
| MJ Beauty Clinic Ltd | Extraterritorial | 2025 |
| MJB Estates Limited | Construction | 2022 |
| MJW Auto Electrical Ltd | Wholesale & retail | 2024 |
| MJW2D Ltd | Real estate | 2024 |
| MK Yeovil Car Service Ltd | Wholesale & retail | 2023 |
| MLR Property Group Ltd | Households | 2023 |
| MM2 Consulting Ltd | Information & communication | 2025 |
| MN8 Consulting Limited | Information & communication | 2009 |
| Mnts Property Ltd | Real estate | 2026 |
| Monarch Laundry (Yeovil) Limited | Other services | 2004 |
| Monk Woodworking Limited | Other services | 1955 |
| Monkton House Limited | Professional & scientific | 2009 |
| Montacute Holdings Limited | Professional & scientific | 2024 |
| Monty Distribution Ltd | Wholesale & retail | 2024 |
| Moorland Enterprises (SW) Limited | Real estate | 2022 |
| Mora Eterna Ltd | Manufacturing | 2026 |
| Morgward Properties Limited | Real estate | 2020 |
| Morley's Electrical Limited | Construction | 1995 |
| Moroak Limited | Wholesale & retail | 1999 |
| Morris Insurance Brokers Limited | Financial services | 2010 |
| Morse Welding Supplies Limited | Wholesale & retail | 1992 |
| Morsys Ltd | Professional & scientific | 2013 |
| Mortarbuy Limited | Real estate | 2016 |
| Mortarsell Limited | Financial services | 2024 |
| Mortimer's (Yeovil) Limited | Manufacturing | 1964 |
| Morton Eaves Limited | Professional & scientific | 2007 |
| Mostly Maintenance Ltd | Administrative & support | 2022 |
| Mostly Media Europe Limited | Professional & scientific | 2001 |