| M.C. Slates Limited | Wholesale & retail | 2004 |
| M.I.N.E. Wind Limited | Manufacturing | 2014 |
| M.R. Horn Transport Limited | Transport & logistics | 1988 |
| Madasa Limited | Financial services | 2017 |
| Magnus Resources Limited | Mining & quarrying | 2023 |
| Maison Aurelia Ltd | Wholesale & retail | 2025 |
| Maize Growers Association | Other services | 1991 |
| Maker Maker Ltd | Wholesale & retail | 2022 |
| Mammal Strength Ltd | Wholesale & retail | 2020 |
| MAN Friday (SW) Limited | Manufacturing | 2008 |
| Mandle Co Ltd | Wholesale & retail | 2021 |
| Mardon Design Ltd | Professional & scientific | 2015 |
| Mark Dewick Health Care Solutions Ltd | Health & social care | 2023 |
| Marshtid Ltd | Construction | 2016 |
| Martin and Bolt Limited | Construction | 2006 |
| Martin Bros. (Builders) Ltd | Construction | 2003 |
| Marzia Properties Limited | Real estate | 2017 |
| Mattenprouse Ltd | Financial services | 2025 |
| Maxiscrape Limited | Extraterritorial | 2013 |
| Maya Electrical Services Ltd | Construction | 2020 |
| MCA Windows and Doors Limited | Manufacturing | 2015 |
| Mcmillan Bass Limited | Professional & scientific | 2005 |
| MCT (Devon) Ltd | Arts & recreation | 2003 |
| Meadfoot Group Ltd | Construction | 2018 |
| Meadow Consulting Limited | Professional & scientific | 2021 |
| Medlars Limited | Real estate | 2009 |
| Megan Stevens Editing Limited | Professional & scientific | 2022 |
| Meldon Homes Ltd | Real estate | 2025 |
| Menear Consulting Limited | Administrative & support | 2008 |
| Mentis Limited | Financial services | 1962 |
| Mercom Services Limited | Information & communication | 2012 |
| Meretrex Ltd | Wholesale & retail | 2016 |
| Merrifield Agriculture Ltd | Agriculture & fishing | 2014 |
| Messrs Limited | Information & communication | 2015 |
| Metcalfe 2 Limited | Information & communication | 2025 |
| Metcalfe Limited | Information & communication | 1999 |
| MG Prime Property Ltd | Real estate | 2023 |
| Mice Wheels Ltd | Wholesale & retail | 2015 |
| MID Devon Car Sales Ltd | Wholesale & retail | 2022 |
| MID Devon Curry Ltd | Hospitality | 2021 |
| MID Devon Music Ltd | Education | 2014 |
| Middle Moor Farm Limited | Agriculture & fishing | 2013 |
| Midmoor Homes (SW) Ltd | Construction | 2019 |
| Midwinter Cooke Limited | Professional & scientific | 2007 |
| Millmoor Woodland Enterprises Ltd | Agriculture & fishing | 2018 |
| Milly's Day Nursery and Pre-School Limited | Education | 2015 |
| Minds Studio Limited | Administrative & support | 2019 |
| Ministry of Media Limited | Information & communication | 2008 |
| MJ Drainage Solutions Ltd | Administrative & support | 2026 |
| MJD Poultry Limited | Agriculture & fishing | 2015 |
| Mmgsd Limited | Manufacturing | 2026 |
| MNR Investments Limited | Real estate | 2013 |
| Mole Avon Trading Limited | Wholesale & retail | 1973 |
| Moor to Moor Structural Ltd | Professional & scientific | 2025 |
| Moorpark Garage Limited | Wholesale & retail | 2026 |
| Morchard Road Garage Management Company Limited | Households | 2021 |
| More Positive ME Community Interest Company | Education | 2016 |
| Morgan Property Maintenance (Devon) Limited | Construction | 2013 |
| Moring Road Properties Limited | Extraterritorial | 2013 |
| Mortimer Farms Limited | Agriculture & fishing | 2011 |
| Moto Ventura Tours Limited | Administrative & support | 2015 |
| MPP Ventures Limited | Hospitality | 2014 |
| MR a S GEE Limited | Health & social care | 2010 |
| MS & TA Worth Ltd | Manufacturing | 2013 |
| MSJ Coaching Ltd | Arts & recreation | 2016 |
| MSK Property (Devon) Limited | Real estate | 2019 |
| N E Level Ltd | Administrative & support | 2021 |
| Nahid DE Belgeonne Limited | Other services | 2019 |
| Naomi Mace Property Ltd | Real estate | 2025 |
| Napleton House Ltd | Hospitality | 2020 |
| Nathan Waddington Painting and Decorating Limited | Construction | 2018 |
| National Sawmills Ltd | Wholesale & retail | 2025 |
| Natson Moor Ltd | Hospitality | 2021 |
| NBK Moto Ltd | Wholesale & retail | 2026 |
| Nebula CNC Limited | Manufacturing | 2025 |
| Neil Passmore Process Engineering Limited | Professional & scientific | 2010 |
| Nettle and Dock Limited | Hospitality | 2014 |
| New British Design Limited | Manufacturing | 2009 |
| New Park Consulting Limited | Professional & scientific | 2023 |
| Newline Drylining Limited | Construction | 2021 |
| Newton Car Sales Limited | Wholesale & retail | 2006 |
| Nick Cann Pest Control Limited | Administrative & support | 2015 |
| Nikki Blanchford Limited | Other services | 2012 |
| Nimkay Foods Ltd | Wholesale & retail | 2021 |
| NKD Rescue Limited | Agriculture & fishing | 2024 |
| NMD Consulting Engineers Limited | Professional & scientific | 2021 |
| Nmpj (UK) Limited | Administrative & support | 2016 |
| NO 3 GIN Bar Ltd | Hospitality | 2021 |
| None Studios Ltd | Information & communication | 2012 |
| Nudge Photography Ltd | Professional & scientific | 2020 |
| NUTS4WHEELS Limited | Wholesale & retail | 2011 |
| Nymet Tracey Contractors Limited | Agriculture & fishing | 2004 |
| Ocean Consultancy Limited | Professional & scientific | 2003 |
| Ocellaris Limited | Information & communication | 2018 |
| Odesto Automotive Ltd | Wholesale & retail | 2025 |
| OHP Trust | Other services | 2022 |
| Old DEN Developments Ltd | Construction | 2018 |
| Old Forge Car Sales Ltd | Wholesale & retail | 2025 |
| Olivers (Crediton) Limited | Manufacturing | 2002 |
| OLR Hotboxes Ltd | Construction | 2024 |