| Mount Batten Sailing and Water Sports Centre | Administrative & support | 1995 |
| Mount Gould Super Store Ltd | Wholesale & retail | 2014 |
| Mount Howe (Management Company) Limited | Households | 1990 |
| Mount Pleasant (Exeter) Limited | Health & social care | 2023 |
| Mountain Top Accountants Limited | Professional & scientific | 2020 |
| Mountain Water Experience Limited | Arts & recreation | 2004 |
| Mountbatten Boathouse Ltd | Wholesale & retail | 2001 |
| Moveswift Group Ltd | Water & waste | 2025 |
| Moxi Engineering Limited | Construction | 2013 |
| Moxilo Ltd | Information & communication | 2019 |
| Moyle Court (Plymstock) Management Limited | Households | 2018 |
| MP Welding Ltd | Construction | 2019 |
| MP4MSERVICES Ltd | Public administration | 2022 |
| MPC Roofing Contractors Ltd | Construction | 2017 |
| MPJ Properties Limited | Real estate | 2021 |
| MPL Properties Limited | Real estate | 2003 |
| Mpnm LLP | | 2008 |
| Mpwh Group Holdings Limited | Financial services | 2026 |
| MR Barbers (Nantwich) Ltd | Other services | 2014 |
| MR Chill Comcat Ltd | Construction | 2025 |
| MR Future Limited | Hospitality | 2025 |
| MR J Hall Limited | Construction | 2016 |
| MR Properties (SW) Ltd | Real estate | 2024 |
| MR Pubs (SW) Ltd | Hospitality | 2024 |
| MR Shane Matthews Ltd | Extraterritorial | 2025 |
| MR Toppings Ltd | Hospitality | 2023 |
| MR Tubs Hot TUB Hire Limited | Other services | 2017 |
| MR Woks Limited | Hospitality | 2018 |
| MR Woks Thai Noodle & Street Food Limited | Hospitality | 2023 |
| MR Worldwide Holdings Limited | Financial services | 2023 |
| MRB Property (SW) Ltd | Real estate | 2022 |
| MRC Elburton Butchery Limited | Wholesale & retail | 2020 |
| Mrclarke Limited | Professional & scientific | 2020 |
| MRS Blossoms Ltd. | Hospitality | 2015 |
| MS Construction Consultancy Ltd | Construction | 2019 |
| MS Global Transport Limited | Transport & logistics | 2026 |
| MSB Property Services Ltd | Construction | 2014 |
| MSF Estates Ltd | Real estate | 2024 |
| MSH Plumbing & Heating Limited | Construction | 2015 |
| MSJ Martial Arts Supplies Limited | Wholesale & retail | 2012 |
| MSM Developments Ltd | Construction | 2020 |
| MT Mobility Limited | Wholesale & retail | 2009 |
| MT Property Protection Limited | Administrative & support | 2025 |
| MT Property Protection Services Ltd | Administrative & support | 2023 |
| MT Radiology Ltd | Health & social care | 2023 |
| MT Soft Limited | Manufacturing | 2011 |
| MT49 Limited | Real estate | 2014 |
| MTA Energy UK Limited | Energy | 2026 |
| Mtabbypubs Ltd | Hospitality | 2024 |
| Mtaxi Ltd. | Wholesale & retail | 2016 |
| Mtgp Ltd | Financial services | 2019 |
| Mtjl Limited | Professional & scientific | 2015 |
| MTK Developments (UK) Limited | Real estate | 2004 |
| MTK Limited | Information & communication | 2003 |
| MUC Capital Limited | Real estate | 2023 |
| Muddy Boots Childcare Ltd | Health & social care | 2017 |
| Muddyman Motors Ltd | Wholesale & retail | 2010 |
| Muffinly & Meltsly Ltd | Hospitality | 2024 |
| Muganzi Ltd | Wholesale & retail | 2021 |
| Muganzirides Ltd | Wholesale & retail | 2026 |
| Mullin Consultancy Limited | Health & social care | 2023 |
| Multihull Centre Limited | Wholesale & retail | 2013 |
| Multihull Centre Services Limited | Manufacturing | 2022 |
| Multihull Developments Ltd | Manufacturing | 2024 |
| Multimarine Composites Limited | Manufacturing | 1998 |
| Multimarine EOT Limited | Administrative & support | 2025 |
| Multimarine Manufacturing Limited | Manufacturing | 2009 |
| Multiple House Ltd | Construction | 2016 |
| Mumbai Foods Limited | Wholesale & retail | 2011 |
| Mumbai Kitchen Group Limited | Hospitality | 2017 |
| Munchachos Ltd | Hospitality | 2017 |
| Munsif Group Ltd | Hospitality | 2025 |
| Murland Kerth Ltd | Real estate | 2020 |
| Murphy Pierce Projects Limited | Real estate | 2024 |
| Murray Holdings (SW) Limited | Professional & scientific | 2017 |
| Murray Plymouth TPS (Devon) Ltd | Wholesale & retail | 2019 |
| Musa Bargain Ltd | Wholesale & retail | 2025 |
| Musa Takeaway Ltd | Hospitality | 2022 |
| Musli Ltd | Construction | 2014 |
| Muslim Schools Education Network Limited | Education | 2025 |
| Musu Ltd | Construction | 2019 |
| Mutant Labs Limited | Information & communication | 2009 |
| Mutese Care Service Ltd | Health & social care | 2024 |
| Mutley Bakery Ltd | Wholesale & retail | 2017 |
| Mutley Barber Ltd | Other services | 2025 |
| Mutley Barbers 1 Ltd | Other services | 2020 |
| Mutley Bazzar Ltd | Wholesale & retail | 2021 |
| Mutley Court Ltd | Real estate | 1996 |
| Mutley Greenbank Trust | Other services | 2000 |
| Mutley Market Ltd | Wholesale & retail | 2025 |
| Mutley New Barber Ltd | Other services | 2024 |
| Mutley Plain Bars Limited | Hospitality | 2007 |
| Mutley Restaurant Ltd | Hospitality | 2023 |
| Mutley Wordlwide Foods Ltd | Wholesale & retail | 2023 |
| MV Consulting SW Ltd | Administrative & support | 2017 |
| MV Properties SW Ltd | Real estate | 2024 |
| MVV Environment Devonport Limited | Energy | 2010 |
| MVV Environment Limited | Financial services | 2008 |
| MVV Environment Medworth Limited | Energy | 2021 |
| MVV Environment Services Limited | Energy | 2013 |