| Moorvale Creative CIC | Arts & recreation | 2017 |
| Moorwild Limited | Agriculture & fishing | 2026 |
| Moredon Game Supplies Limited | Agriculture & fishing | 2001 |
| Moreton Tree Investments Ltd | Real estate | 2017 |
| Morgan Builders (South West) Limited | Construction | 2011 |
| Morgan M Richards Ltd | Professional & scientific | 2021 |
| Morgan Property Investments South West Limited | Real estate | 2025 |
| Morgans Quarter Management Company Ltd | Households | 2023 |
| Mori NO Kumasan Ltd | Wholesale & retail | 2018 |
| Morpheus Rentals Ltd | Information & communication | 2022 |
| Morse Property Consultants Limited | Administrative & support | 2004 |
| Mortemmett Ltd | Other services | 2025 |
| Mortgage Select (SW) Limited | Financial services | 2004 |
| Mosaic (Yeovil) Management Company Limited | Households | 2006 |
| Motcomb Kitchens Ltd | Wholesale & retail | 2013 |
| Motiar Catering Ltd | Hospitality | 2022 |
| Moto-Jo Ltd | Wholesale & retail | 2025 |
| Motohead Limited | Professional & scientific | 2023 |
| Motor Claim Service Limited | Financial services | 2014 |
| Motorhead Garage UK Ltd | Other services | 2019 |
| Mouldtec Limited | Manufacturing | 2004 |
| Moule Properties Ltd | Administrative & support | 2025 |
| Mount a Brick Ltd | Wholesale & retail | 2026 |
| Mount Hawke Stores PVT Limited | Wholesale & retail | 2025 |
| Mount Street Garage Limited | Wholesale & retail | 2006 |
| Mountfields Carpentry Limited | Construction | 2014 |
| Mountstephens Electrical Ltd | Construction | 2016 |
| Mountway Consulting Ltd | Real estate | 2026 |
| Mountway School of Dancing Limited | Education | 2018 |
| Moving Performance Limited | Professional & scientific | 2009 |
| Moving Performance Management Ltd | Administrative & support | 2019 |
| Moxom Property Limited | Real estate | 2024 |
| Mozax Care Limited | Health & social care | 2016 |
| MP Cleaning Services(Devon) Ltd | Administrative & support | 2022 |
| MPA Agronomy Ltd | Wholesale & retail | 2026 |
| Mpbmr Limited | Construction | 2026 |
| MPG90 Limited | Construction | 2024 |
| MPH Drylining Limited | Construction | 2021 |
| MPH Telecom and Data Ltd | Information & communication | 2023 |
| Mppm Wine Bar Ltd | Wholesale & retail | 2019 |
| MR and GK Law Ltd | Real estate | 2024 |
| MR F G, MRS N K and MR a J Gammon Limited | Agriculture & fishing | 2013 |
| MR Properties (Swindon) Limited | Real estate | 2025 |
| MR Zero Vapes Ltd | Wholesale & retail | 2026 |
| MRJ Civils Limited | Construction | 2011 |
| Mrmu (Backlands) Limited | Professional & scientific | 2021 |
| Mrmu (HIE) Limited | Hospitality | 2011 |
| MRS Kleen Limited | Administrative & support | 2011 |
| MS Cleaning SW Ltd | Extraterritorial | 2023 |
| MS Topco Ltd | Financial services | 2021 |
| MSB (Taunton) Holdings Ltd | Financial services | 2024 |
| MSC Products Ltd | Professional & scientific | 2024 |
| MSJ Homes Ltd | Real estate | 2020 |
| Msm&D Ltd | Professional & scientific | 2025 |
| Msvc Ltd | Professional & scientific | 2021 |
| MTM Tiling Limited | Construction | 2013 |
| MTS Consultancy Limited | Professional & scientific | 1999 |
| MUD Mountain Limited | Wholesale & retail | 2016 |
| Mudgley Farm Ltd | Construction | 2009 |
| Muhammad Suleman Ltd | Wholesale & retail | 2025 |
| Mulberry Tree Properties Limited | Real estate | 2014 |
| Mulder Holding Ltd | Professional & scientific | 2005 |
| Murrin Associates Limited | Financial services | 2004 |
| Murtagh Civils and Setting OUT Engineer Ltd | Construction | 2015 |
| Murz Limited | Wholesale & retail | 2022 |
| Mushroom Box Ltd | Manufacturing | 2023 |
| Music for ALL | Arts & recreation | 1996 |
| Music Guru Lessons Ltd | Education | 2021 |
| Music Lessons Anywhere Ltd | Education | 2021 |
| Music Theory Anywhere Ltd | Education | 2025 |
| Musicola Limited | Wholesale & retail | 2011 |
| Musson+Retallick Limited | Arts & recreation | 2013 |
| MV Architecture Ltd | Professional & scientific | 2023 |
| MV Freelance Limited | Health & social care | 2023 |
| MW (Southwest) Holding Company Limited | Real estate | 2022 |
| MWT Enterprises Limited | Hospitality | 2013 |
| My Future Living Limited | Real estate | 2021 |
| My Home Pet VET Ltd | Professional & scientific | 2021 |
| My Little Essentials Ltd | Wholesale & retail | 2026 |
| My Sport Travel Limited | Administrative & support | 2019 |
| My Super Car Photo Limited | Professional & scientific | 2023 |
| Mybarrister Ltd | Professional & scientific | 2012 |
| Mynard and Smith (Oundle) Limited | Real estate | 1966 |
| Myra Jean Ltd | Construction | 2024 |
| Myth Division Ltd | Information & communication | 2025 |
| N & G Construction Limited | Construction | 2008 |
| N & N Land Development Ltd | Construction | 2018 |
| N & S Associates Limited | Professional & scientific | 1994 |
| N & V Hanlon Building & Decorating Limited | Construction | 2010 |
| N Friendship & Sons Funeral Directors Ltd | Other services | 2020 |
| N S Jones Limited | Manufacturing | 2026 |
| N'Sign International Ltd | Information & communication | 1998 |
| N. F. Clothier & Sons Limited | Agriculture & fishing | 1973 |
| Nac's West Care Ltd | Health & social care | 2021 |
| Nails by TIL Limited | Other services | 2025 |
| Nailsea Medical LLP | | 2012 |
| Naina UK Ltd | Hospitality | 2024 |
| NAK Muay Training Limited | Wholesale & retail | 2022 |
| Nandi Logistics Ltd | Transport & logistics | 2025 |
| Nannova Ltd | Professional & scientific | 2015 |