| Making Moves Exeter Ltd | Hospitality | 2023 |
| Makinson Homes Limited | Construction | 2014 |
| Maktech Consulting Ltd | Information & communication | 2018 |
| Makumbe Ltd | Health & social care | 2024 |
| Maladee Property Limited | Construction | 2023 |
| Malama Wealth Limited | Financial services | 2024 |
| Malaya Publishing Ltd | Information & communication | 2018 |
| Malayalikkada Ltd | Wholesale & retail | 2023 |
| Maldon Homes Limited | Construction | 2015 |
| Malibu Hair UK Ltd | Other services | 2024 |
| Mallard Property (Exeter) Limited | Real estate | 2015 |
| Mallory Grant Holdings Limited | Financial services | 2020 |
| Mallory Grant Limited | Wholesale & retail | 2001 |
| Mallory Holdings Limited | Administrative & support | 2002 |
| Mallory International Limited | Other services | 1994 |
| Malta Recycling Limited | Administrative & support | 2024 |
| Malton's Properties Limited | Real estate | 2020 |
| Maltymint PUB Company Ltd | Hospitality | 2015 |
| Mama Fletch Ltd | Hospitality | 2018 |
| Mamhead Castle Limited | Real estate | 2012 |
| Mamhead Management Ltd | Administrative & support | 2020 |
| Mammoth Strength Club Ltd | Wholesale & retail | 2022 |
| Management Solutions SW Ltd | Transport & logistics | 2024 |
| Manchester Power Solutions Limited | Professional & scientific | 2017 |
| Mandalia Limited | Health & social care | 2015 |
| Mandy WAX Therapy Ltd | Health & social care | 2025 |
| Mane Buildings Limited | Real estate | 2019 |
| Manfield Investments Limited | Other services | 2023 |
| Manglin Limited | Real estate | 2012 |
| Mango Evolution Limited | Information & communication | 2003 |
| Mango Melon Limited | Financial services | 2019 |
| Mango Plumbing & Drainage Services Ltd | Construction | 2023 |
| Mani Cornershop Ltd | Real estate | 2021 |
| Maniyar Services Limited | Health & social care | 2022 |
| Mann Asset Group Ltd | Financial services | 2023 |
| Mann Power Generation Limited | Energy | 2012 |
| Manna ASH Court (Exeter) Management Company Limited | Households | 1974 |
| Mannarest Limited | Hospitality | 1964 |
| Manner Properties Ltd | Households | 2023 |
| Mannis Live Ltd | Administrative & support | 2019 |
| Manojmanish Holdings Ltd | Wholesale & retail | 2025 |
| Manor Farm Mews Limited | Households | 1990 |
| Manor Farm Park Limited | Energy | 2014 |
| Manor House (Marylebone) Limited | Real estate | 2006 |
| Manor House Holidays Ltd | Financial services | 2023 |
| Manor Mill Limited | Real estate | 2006 |
| Manor Print Shop Limited | Manufacturing | 2005 |
| Manor Validation Limited | Professional & scientific | 2023 |
| Mantia Properties Limited | Real estate | 2024 |
| Mantra Exeter Ltd | Other services | 2018 |
| Mantracourt Electronics Limited | Manufacturing | 1983 |
| Manx IT Ltd | Information & communication | 2022 |
| Maple Cross Management Company Limited | Households | 2025 |
| Maplewood Grange (Exeter) Management Company Limited | Households | 2025 |
| Marble Court Business Park TQ Ltd | Real estate | 2023 |
| Marbri Properties Ltd | Real estate | 2026 |
| March Farriers Limited | Agriculture & fishing | 2013 |
| Marco's Italian Limited | Hospitality | 2018 |
| Marco's Pasta Ltd | Hospitality | 2024 |
| Marcus Tozer & Co Ltd | Professional & scientific | 2018 |
| Maria Escribano Architects Ltd | Professional & scientific | 2020 |
| Mariamz Consulting Limited | Information & communication | 2013 |
| Marian Kocan Transport Ltd | Transport & logistics | 2014 |
| Marigold Pharma Limited | Wholesale & retail | 2023 |
| Marina Court (Exmouth) Limited | Households | 2004 |
| Marine Consultancy and Training Ltd | Professional & scientific | 2025 |
| Marine Electronics Ltd | Manufacturing | 2012 |
| Marine Mapping Ltd. | Information & communication | 2011 |
| Marinedeck UK & Eire Limited | Manufacturing | 2019 |
| Mario's Motor's (SW) Ltd | Wholesale & retail | 2017 |
| Marisol Properties Limited | Real estate | 2023 |
| Marius Daniel Transport Limited | Transport & logistics | 2026 |
| Marjon Tenancies 1 Limited | Real estate | 1993 |
| Mark Adie Ltd | Administrative & support | 2005 |
| Mark Blaber Landscaping Limited | Administrative & support | 2017 |
| Mark Bushby Optometrists Limited | Health & social care | 1962 |
| Mark Downey Ltd | Construction | 2025 |
| Mark Dyson Surveyors Limited | Professional & scientific | 2011 |
| Mark James Hawkins Limited | Extraterritorial | 2025 |
| Mark NH Consulting Ltd | Professional & scientific | 2019 |
| Mark Payne (SW) Limited | Construction | 1997 |
| Mark Phillips Limited | Administrative & support | 2008 |
| Mark Russ Trading Ltd | Health & social care | 2018 |
| Mark Whittle Limited | Administrative & support | 2008 |
| Markay Estates Ltd | Real estate | 2021 |
| Market Carpets Ltd | Wholesale & retail | 2003 |
| Market Carpets Properties Limited | Real estate | 2018 |
| Market Carpets SW Ltd | Financial services | 2021 |
| Market Carpets Trustee Limited | Professional & scientific | 2021 |
| Market Fields (Sturminster Newton) Management Company Limited | Real estate | 2025 |
| Marketing and SEO UK Ltd | Information & communication | 2021 |
| Marks Brothers Roofing Limited | Construction | 2019 |
| Markwell House Limited | Households | 2000 |
| Marlborough Court (Services) Co. Limited | Households | 1989 |
| Marlborough D. P. Limited | Health & social care | 2007 |
| Marles Farm Services Limited | Construction | 2012 |
| Marleway Ltd | Transport & logistics | 2022 |
| Marlow & Co Accountants Ltd | Administrative & support | 2009 |
| Maroon Duck Limited | Extraterritorial | 2011 |
| Marquis & Lord Limited | Professional & scientific | 2001 |