| Merlot Black Ltd | Administrative & support | 2024 |
| Merrett Houmoller Limited | Professional & scientific | 2015 |
| Merretts Mills Industrial Centre Limited | Professional & scientific | 1999 |
| Merus Software Limited | Information & communication | 2001 |
| Meta Digital Accounting Ltd | Administrative & support | 2023 |
| Metal Choirs Limited | Professional & scientific | 2017 |
| Metaverse Realtors Limited | Real estate | 2022 |
| Metel Restoration Ltd | Construction | 2015 |
| Mevagissey Methodist Chapel Management Company Limited | Households | 2003 |
| MFB Retail Ltd | Wholesale & retail | 2020 |
| MI Works (South West) Ltd | Construction | 2012 |
| MI Works Property Maintenance Ltd | Construction | 2012 |
| Michael Pritchett Limited | Agriculture & fishing | 1961 |
| Michael Property Management Ltd | Real estate | 2019 |
| Michaelwood PV & Bess Limited | Energy | 2024 |
| Michelle Holland Design Ltd | Construction | 2018 |
| Microtricity Limited | Professional & scientific | 2005 |
| Middlecote Ltd | Wholesale & retail | 2005 |
| Midge Property Limited | Real estate | 2021 |
| Mike Acton Building & Renovation Ltd | Construction | 2011 |
| Mike Butt Transport Limited | Transport & logistics | 2021 |
| Miko FD Ltd | Professional & scientific | 2018 |
| Miles Motor Services Ltd | Wholesale & retail | 2017 |
| Mill Lodge Properties Limited | Construction | 1968 |
| Millar Howard Investment 2 Limited | Extraterritorial | 2014 |
| Millar Howard Workshop Limited | Professional & scientific | 2005 |
| Mills Brewing Ltd | Manufacturing | 2025 |
| Mills Goodwin Talent Network Limited | Professional & scientific | 2012 |
| Milly Sinclair Associates Limited | Professional & scientific | 2019 |
| Minch Health Limited | Real estate | 2020 |
| Minchinhampton Community Hub CIC | Real estate | 2022 |
| Minchinhampton Community Library Trust Ltd. | Arts & recreation | 2012 |
| Minchinhampton Cotswold Club Limited(The) | Hospitality | 1977 |
| Minchinhampton Golf Club Limited (the) | Arts & recreation | 1972 |
| Minchinhampton Rugby Football Club Limited | Arts & recreation | 2010 |
| Minchinhampton Smile Ltd | Health & social care | 2020 |
| Mini Magic Makers Ltd | Wholesale & retail | 2025 |
| Minipart.Co.Uk Ltd | Wholesale & retail | 2005 |
| Minsmere Power Limited | Energy | 2011 |
| Minsmere Solar Limited | Energy | 2016 |
| Mintowt Wealth Management Ltd | Financial services | 2024 |
| Miro Psychometrics Limited | Information & communication | 2008 |
| Miserden Investments Limited | Real estate | 2018 |
| Miserden Stores Ltd | Wholesale & retail | 2015 |
| Miserden Sustainable Limited | Wholesale & retail | 2014 |
| MJP Book-Keeping Limited | Professional & scientific | 2003 |
| MKS Projects Limited | Information & communication | 2012 |
| ML PR & Marketing Ltd | Professional & scientific | 2021 |
| Mmplumber Ltd | Information & communication | 2023 |
| Moat Contracting Limited | Construction | 2021 |
| Mobile Smile Ltd | Health & social care | 2019 |
| Mobilisation LAB CIC | Professional & scientific | 2025 |
| Mobot Design Ltd | Information & communication | 2018 |
| MOD54 Limited | Professional & scientific | 2014 |
| Modern Grantmaking Ltd | Professional & scientific | 2016 |
| Moly Trading Limited | Financial services | 2015 |
| Molyneux Design Ltd | Manufacturing | 2026 |
| Momentum Lane Ltd | Administrative & support | 2026 |
| Monkey Dog Pictures Ltd | Information & communication | 2023 |
| Montal Holdings Limited | Financial services | 2024 |
| Montal Limited | Wholesale & retail | 2020 |
| Montana Floss Co. Ltd. | Information & communication | 2014 |
| Montpellier International Consulting Limited | Professional & scientific | 2002 |
| Monty Rail Ltd | Professional & scientific | 2018 |
| Montyandco Ltd. | Manufacturing | 2015 |
| Moonflight Ltd | Hospitality | 2018 |
| Moonshroom Ltd | Manufacturing | 2021 |
| Moor Court Residents Association Limited | Households | 2003 |
| Morgan Barnfield Construction Limited | Construction | 2015 |
| Morgans Property Maintenance Limited | Administrative & support | 2013 |
| Morley Asset Management Limited | Administrative & support | 2013 |
| Moser Limited | Arts & recreation | 2007 |
| Motion Maverick Ltd | Information & communication | 2023 |
| Motorfix (Stroud) Ltd | Wholesale & retail | 2021 |
| Mount Pleasant Quarry Limited | Construction | 2023 |
| Mountbatten Property Investment Limited | Real estate | 2018 |
| Moving Light Design Ltd | Arts & recreation | 2021 |
| Moxie Energy Limited | Professional & scientific | 2020 |
| MR and MRS Productions Ltd | Information & communication | 2013 |
| MR. Souvlaki Leamington Spa Ltd | Manufacturing | 2023 |
| Msqrd Labs Ltd | Information & communication | 2025 |
| MTB Collections Ltd | Wholesale & retail | 2025 |
| Mtdflow Ltd | Information & communication | 2026 |
| MTT Fine Art & Craft Ltd | Wholesale & retail | 2014 |
| Muddy Little Boots Publishing Limited | Information & communication | 2021 |
| Muffin Money Ltd | Financial services | 2021 |
| Mugswell Nursery Ltd | Construction | 2003 |
| Multi-Me Ltd | Information & communication | 2010 |
| Multimedia Outsourcing UK Ltd | Information & communication | 2008 |
| Multiverse Realty Limited | Real estate | 2022 |
| Multris Limited | Information & communication | 2016 |
| Mumo Ltd | Wholesale & retail | 2026 |
| Murrays Estate Agents Limited | Real estate | 2013 |
| My Leather Key FOB Ltd | Wholesale & retail | 2020 |
| Myce Ltd | Professional & scientific | 2025 |
| Mzima Limited | Administrative & support | 1999 |
| N M Stroud Ltd | Financial services | 2023 |
| N.G. Irelan-Hill Painting & Decorating Limited | Construction | 2002 |
| N.J. Usher & SON Limited | Construction | 2002 |
| Naff Food Ltd | Manufacturing | 2020 |