| Moorview Pet Cremation Ltd | Other services | 2023 |
| MOR Edrin (London) Limited | Real estate | 2023 |
| MOR Edrin Limited | Real estate | 2022 |
| Morada Property Management Limited | Real estate | 2021 |
| Morada Works Limited | Professional & scientific | 2025 |
| Morat Ltd | Wholesale & retail | 2022 |
| More Than Just a PA Limited | Administrative & support | 2021 |
| Morehaus Limited | Construction | 2023 |
| Morgan Hartnell Ltd | Financial services | 2016 |
| Morgan Hill Consultants Limited | Information & communication | 2001 |
| Morgan Leith Limited | Professional & scientific | 2024 |
| Mornacott Conservation Limited | Real estate | 2023 |
| Morph and HUE Ltd | Wholesale & retail | 2025 |
| Mortgage Solutions Group Ltd | Financial services | 2026 |
| Mortimer Residential Ltd | Real estate | 2024 |
| Mortonlaw Specialist Employment Lawyers Limited | Professional & scientific | 2010 |
| Morwenna Property Ltd | Real estate | 2025 |
| Mosazi Modal Logistics Ltd | Professional & scientific | 2025 |
| Mosfet Group Ltd | Other services | 2021 |
| Moss Builders (South West) Limited | Construction | 2003 |
| Moss Engineering Inc Ltd | Wholesale & retail | 2023 |
| Moss Marine Construction Limited | Construction | 1998 |
| Motachase Limited | Wholesale & retail | 1987 |
| Motion Clinic Exeter Ltd | Health & social care | 2023 |
| Motionarch Properties Limited | Real estate | 1996 |
| Motor Animations Ltd | Information & communication | 2017 |
| Motor Industry Legal Services Limited | Professional & scientific | 2022 |
| Mouldforce Ltd | Water & waste | 2025 |
| Mount Evermas Property Investment Limited | Real estate | 2020 |
| Mount Wear Court Management Limited | Households | 2014 |
| Mountain Action Holidays Limited | Administrative & support | 2018 |
| Mowdy Ltd | Real estate | 2017 |
| Mozi Carpentry Ltd | Manufacturing | 2021 |
| MP Labs Ltd | Information & communication | 2025 |
| MR Mind Ltd | Other services | 2025 |
| MR R M Bethune Ltd | Health & social care | 2016 |
| MRG Business Services Ltd | Professional & scientific | 2022 |
| MRM Design Studio Ltd | Professional & scientific | 2017 |
| MRR (Investments) Limited | Financial services | 2025 |
| MRT 82 Ltd | Construction | 2018 |
| MRW Law Limited | Professional & scientific | 2011 |
| MSA (SW) Ltd | Hospitality | 2024 |
| MSA Investigations Ltd | Administrative & support | 2023 |
| MSA Professional Properties Ltd | Real estate | 2020 |
| Mscle Limited | Extraterritorial | 2024 |
| MSD Feast Limited | Hospitality | 2026 |
| MSK300 Ltd | Manufacturing | 2025 |
| MSP Exeter Ltd | Construction | 2017 |
| MT Allen Engineering Limited | Construction | 2014 |
| MT Equestrian Services Ltd | Agriculture & fishing | 2022 |
| MTB Total Solutions Limited | Construction | 2020 |
| MTC Europe Ltd | Real estate | 2017 |
| MTC Ship Express Limited | Transport & logistics | 2025 |
| Mud-Ventures Ltd | Education | 2023 |
| Muddy Hands Mentoring and Wellbeing CIC | Education | 2026 |
| Mulberry Catering Co Ltd | Hospitality | 2018 |
| Mulberry FIR Ltd | Construction | 2019 |
| Mulberry House Holdings Limited | Financial services | 2016 |
| Mulberry Investment Group Limited | Construction | 2005 |
| Mulberry Marketing Communications Limited | Professional & scientific | 1995 |
| Mulberry Studios Limited | Information & communication | 2002 |
| Mulki Hire Ltd | Administrative & support | 2019 |
| Mullins Associates Ltd | Professional & scientific | 2014 |
| MULTI21 Limited | Professional & scientific | 2024 |
| Multileasing Limited | Administrative & support | 2001 |
| Multilingua Devon CIC | Administrative & support | 2009 |
| Multimax Marketing Ltd | Wholesale & retail | 2012 |
| Multiple Sclerosis Therapy Centre South West Limited | Health & social care | 1988 |
| Multiserve Group Ltd | Health & social care | 2023 |
| Munchkins Day Nursery Limited | Education | 2004 |
| Murathan 29 Ltd | Hospitality | 2024 |
| Murray Fields (Exeter) Ltd | Financial services | 2025 |
| Murray French (Exeter) Limited | Real estate | 1972 |
| Murray French 2010 Limited | Real estate | 2010 |
| Murray French Exeter 2024 Limited | Financial services | 2024 |
| Muscle Machine (SW) Ltd | Other services | 2022 |
| Muscle Machine CWS Ltd | Arts & recreation | 2024 |
| Muscle Machine PT Ltd | Arts & recreation | 2021 |
| Muscle Machine STA Ltd | Arts & recreation | 2024 |
| Music in Devon Initiative C.I.C. | Arts & recreation | 2016 |
| Musicdevon Co-Operative Limited | Education | 2004 |
| Mustang Holdings Limited | Real estate | 2017 |
| Mustin Wealth Management Ltd | Professional & scientific | 2026 |
| Musto Transport Ltd | Transport & logistics | 2024 |
| Mutley Distillery Ltd | Manufacturing | 2020 |
| Muzzy Marine Limited | Administrative & support | 2015 |
| Mvremovals (SW) Ltd | Transport & logistics | 2022 |
| Mvremovals.Com Ltd | Transport & logistics | 2022 |
| MW Gozna Services Ltd | Construction | 2003 |
| MW Tall Construction Ltd | Construction | 2014 |
| MWO Limited | Health & social care | 2016 |
| MWR Scaffolding and Roofing Ltd | Construction | 2023 |
| MXF Logistics Limited | Transport & logistics | 2026 |
| My Box Space Limited | Transport & logistics | 2019 |
| My Candle Light Ltd | Arts & recreation | 2025 |
| My Casa Your Casa Ltd | Real estate | 2022 |
| My Choice Exeter Ltd | Health & social care | 2025 |
| My Homes Group Ltd | Extraterritorial | 2022 |
| My Life KIT Ltd | Information & communication | 2021 |
| My Tax Team Ltd | Professional & scientific | 2012 |