| Modbury Facilities Limited | Administrative & support | 2025 |
| Modbury Pharmacy Limited | Wholesale & retail | 2002 |
| Modelland Ltd | Wholesale & retail | 2025 |
| Modern Catering Limited | Hospitality | 2014 |
| Modern Heat Home Solutions Ltd | Construction | 2024 |
| Mohamed Hossam Studio Ltd | Administrative & support | 2021 |
| Mohaus Ltd | Information & communication | 2026 |
| Mokkō Ltd | Manufacturing | 2020 |
| Molesworth Road Management Limited | Households | 2001 |
| Mollies Coffee Shop Ltd | Hospitality | 2026 |
| Molly Moon Limited | Arts & recreation | 2011 |
| Molveno Foods Ltd | Hospitality | 2019 |
| Molyneux Associates Limited | Financial services | 2004 |
| Mombay Brasserie Ltd | Hospitality | 2011 |
| Monet & Rove Capital Partners Ltd | Real estate | 2026 |
| Monet & Rove Livgreen Investments Ltd | Other services | 2026 |
| Monet & Rove Thergis Ltd | Financial services | 2026 |
| Monetary Perspectives Limited | Administrative & support | 2013 |
| Moneycasino Ltd | Arts & recreation | 2022 |
| Monk & Partners (SEV) Limited | Professional & scientific | 2020 |
| Monk Investment Management Ltd | Real estate | 1995 |
| Monmouth Park Estate Management Ltd | Real estate | 2022 |
| Montemax Limited | Real estate | 2004 |
| Montgomery Cottages Ltd | Real estate | 2025 |
| Montgomery Transfers Limited | Transport & logistics | 2025 |
| Montpellier Apartments Teignmouth (Freehold) Limited | Households | 2023 |
| Montpellier Teignmouth RTM Company Ltd | Households | 2021 |
| Monty's Classic Motorcycles Ltd | Wholesale & retail | 2013 |
| Monvrai Studio Ltd | Professional & scientific | 2026 |
| MOO Music Plymouth Ltd | Education | 2023 |
| Moolahfy Limited | Information & communication | 2025 |
| Moomin Properties Limited | Real estate | 2023 |
| Moondogz Mental Health Kayaking Support Group CIC | Arts & recreation | 2023 |
| Moongales Ltd | Manufacturing | 2025 |
| Moonstone Associates Limited | Professional & scientific | 1998 |
| Moor Consult Limited | Professional & scientific | 2016 |
| Moor Hearing Ltd | Health & social care | 2019 |
| Moor Holdings Limited | Financial services | 2016 |
| Moor Manage (CM) Limited | Construction | 2015 |
| Moor Power Limited | Extraterritorial | 2016 |
| Moor to Coast Electrical Services SW Ltd | Construction | 2026 |
| Moor to Life Education & Wellbeing CIC | Education | 2021 |
| Moor View (South Brent) Ltd | Real estate | 2005 |
| Moore Ceramics Limited | Construction | 2021 |
| Moore Construction Southwest Ltd | Construction | 2022 |
| Moorely Properties Limited | Real estate | 2010 |
| Moorheat Solutions Limited | Construction | 2018 |
| Moorhill Consulting Limited | Professional & scientific | 2025 |
| Moorland Heating Limited | Construction | 2009 |
| Moorland OIL Ltd | Construction | 2024 |
| Moorland Reach Plymouth Management Company Limited | Households | 2005 |
| Moorland Road Garage Limited | Wholesale & retail | 2011 |
| Moorland Rovers Ltd | Wholesale & retail | 2019 |
| Moorland View Properties Ltd | Real estate | 2023 |
| Moorland Villas Management Limited | Real estate | 2009 |
| Moorlands (Chagford) Limited | Households | 2003 |
| Moorside Garage (SW) Ltd | Wholesale & retail | 2021 |
| Moorsys Ltd | Information & communication | 2014 |
| Moorview Lets Ltd | Real estate | 2018 |
| Moorview Property Developments Ltd | Real estate | 2015 |
| Moorview Property Ltd | Real estate | 2015 |
| MOP, Bucket & Broom Ltd | Administrative & support | 2018 |
| Moras Brothers Limited | Transport & logistics | 2017 |
| Morbro Ltd | Other services | 2024 |
| Morehouse Services Ltd | Wholesale & retail | 2023 |
| Morello Property Limited | Real estate | 2023 |
| Morgan Properties (South West) Ltd | Real estate | 2019 |
| Morgan Shopfitting Services LLP | | 2004 |
| Morganhay Limited | Real estate | 2026 |
| Morley Court Limited | Construction | 2017 |
| Morning Rise Delivering Ltd | Transport & logistics | 2023 |
| Morph Marketing SW Ltd | Administrative & support | 2024 |
| Morpha Media Ltd | Information & communication | 2016 |
| Morpop Safety Limited | Administrative & support | 2013 |
| Morris Engineering Limited | Professional & scientific | 1999 |
| Morris Engineering New Holdco Limited | Financial services | 2023 |
| Mortar Renovations Management Ltd | Construction | 2017 |
| Mortgage & Insurance Services (SW) Ltd | Financial services | 2010 |
| Mortgage HQ Limited | Professional & scientific | 2022 |
| Mortgages 4 Plymouth Ltd | Financial services | 2014 |
| Mortimer Lodge Freehold Limited | Real estate | 1988 |
| Mortimer's Jewellers Limited | Wholesale & retail | 2009 |
| Morvent Mining Limited | Mining & quarrying | 2009 |
| Morweth Court Limited | Households | 2003 |
| Mosaic Masterpiece Ltd | Wholesale & retail | 2024 |
| Moses Court Management (NO.2) Limited | Households | 1989 |
| Moses Court Management Limited | Households | 1988 |
| Moss Automotive Ltd | Wholesale & retail | 2019 |
| Moss Eco Flooring Limited | Construction | 2012 |
| Moss Facilities Ltd | Construction | 2021 |
| Mostlot Limited | Wholesale & retail | 1994 |
| Motherbrew Ltd | Manufacturing | 2019 |
| Motivation Digital Ltd | Information & communication | 2019 |
| Motivation Group Ltd | Information & communication | 2016 |
| Motor Yacht Solutions Limited | Professional & scientific | 2014 |
| Motors South West Limited | Transport & logistics | 1991 |
| Motorvalley Limited | | 1992 |
| Mould & Muse Ltd | Arts & recreation | 2025 |
| Mount Batten Holdings Ltd | Financial services | 2026 |
| Mount Batten Park Limited | Arts & recreation | 1994 |