| MD Sapling Limited | Professional & scientific | 2026 |
| MD Town Planning Limited | Professional & scientific | 2023 |
| Mdcp Consultancy Limited | Information & communication | 2024 |
| MDH Groundworks & Maintenance Limited | Construction | 2015 |
| MDJ2 Associates Limited | Professional & scientific | 2010 |
| MDJ2 Consulting Limited | Administrative & support | 2005 |
| Mdln Nexus Limited | Information & communication | 2026 |
| MDM Developments (Southern) Limited | Construction | 2002 |
| Mdwg Consulting Limited | Information & communication | 2020 |
| Meade Property Limited | Real estate | 2017 |
| Meantime Limited | Professional & scientific | 2010 |
| Measureport Limited | Information & communication | 1993 |
| MED Analytics Limited | Information & communication | 2016 |
| MED Street Ltd | Hospitality | 2024 |
| Meday Ltd | Other services | 2022 |
| Medelinked Ltd | Information & communication | 2005 |
| Medicare Services Installations Ltd. | Health & social care | 1996 |
| Medicuslex Limited | Health & social care | 2014 |
| MEDIK9 Ltd | Wholesale & retail | 2016 |
| MEGA3 Utilities Ltd | Professional & scientific | 2014 |
| Megabowl Limited | Extraterritorial | 2008 |
| Meica Design Limited | Professional & scientific | 2015 |
| Meisner Limited | Professional & scientific | 2012 |
| Meiwai Limited | Wholesale & retail | 2024 |
| MEL Dyson Limited | Information & communication | 2021 |
| Melhado Limited | Construction | 2020 |
| Memo Solutions Limited | Wholesale & retail | 2015 |
| MEN at the Farm CIC | Health & social care | 2025 |
| MEN Don'T Blush Ltd | Wholesale & retail | 2019 |
| Menteith Limited | Information & communication | 2019 |
| MENTOR360 Limited | Administrative & support | 2020 |
| Meon Valley Building Consultancy Limited | Professional & scientific | 2018 |
| Mercantile Accountants Ltd | Financial services | 2017 |
| Mercantile Consultants Ltd | Professional & scientific | 2025 |
| Mercator & Pistor Limited | Wholesale & retail | 2024 |
| Meridian Commercial Refurbishments Ltd | Construction | 2018 |
| Meridian Home Investments Ltd | Real estate | 2022 |
| Meridian Meats Ltd. | Wholesale & retail | 2005 |
| Meridian Mechanical Services (Dorset) Limited | Construction | 2012 |
| Merkabah Retreats Limited | Arts & recreation | 2021 |
| Merryburn Consulting Limited | Professional & scientific | 2022 |
| Meshmade Limited | Professional & scientific | 2025 |
| Metal Finishings Limited | Manufacturing | 1996 |
| Metallic Media Limited | Information & communication | 2011 |
| Methodexcel Ltd | Information & communication | 2016 |
| Metian Advisory Limited | Professional & scientific | 2026 |
| Metismos Ltd | Information & communication | 2017 |
| Metisx Consulting Ltd | Professional & scientific | 2023 |
| Metta Consulting Limited | Administrative & support | 2012 |
| Mews Consultancy Limited | Professional & scientific | 2022 |
| Meyrick Gate Residents RTM Company Limited | Households | 2004 |
| MF Dynamics Consulting Limited | Information & communication | 2022 |
| MFG2024 Limited | Information & communication | 2024 |
| MG Communications Limited | Professional & scientific | 2001 |
| MG Morgan Limited | Professional & scientific | 2013 |
| MGB Wealth Management Limited | Financial services | 2012 |
| Mgok Consulting Limited | Administrative & support | 2016 |
| Mgok Enterprises Limited | Administrative & support | 2016 |
| Mhrproperty Ltd | Real estate | 2021 |
| Mias Marine Limited | Manufacturing | 2023 |
| Michael Coady Consultancy Limited | Information & communication | 2022 |
| Michael Lester Practice Limited | Financial services | 2006 |
| Michelli Glass Limited | Wholesale & retail | 2016 |
| Mickyhcorbett Productions Limited | Arts & recreation | 2010 |
| Miclaw Management Ltd | Professional & scientific | 2017 |
| Micro Power Electronics Limited | Manufacturing | 1991 |
| Microcebus Limited | Information & communication | 2010 |
| Midair Aviation Paint Ltd | Manufacturing | 2025 |
| Middenhead Limited | Information & communication | 2018 |
| Midnight Chef Ltd | Information & communication | 2023 |
| Midnight Design & Print Ltd | Professional & scientific | 2020 |
| Midori Consultants Ltd | Professional & scientific | 2022 |
| Migi Ltd | Wholesale & retail | 2019 |
| Migration Consultants Limited | Information & communication | 2007 |
| Miji Consulting Ltd | Information & communication | 2022 |
| Mike Haycox Financial Planning Ltd | Financial services | 2008 |
| Mikey's Dog Rescue CIC | Administrative & support | 2025 |
| Milderhurst Limited | Professional & scientific | 2026 |
| Miles Associates Ltd | Professional & scientific | 2014 |
| Milestones Matter Ltd | Information & communication | 2019 |
| Milika Limited | Agriculture & fishing | 2025 |
| Milkchip Limited | Information & communication | 2012 |
| Mill Court Wimborne Management Ltd | Households | 2022 |
| Milla Zagluvek Limited | Manufacturing | 2015 |
| Millbank Northwest Engineering Ltd | Professional & scientific | 2025 |
| Miller Entertainments Limited | Arts & recreation | 2021 |
| Miller Holdings (U.K) Ltd | Real estate | 2018 |
| Millhawke Trading Limited | Professional & scientific | 2003 |
| Millmoor Farm Ltd | Real estate | 2014 |
| Millosie Limited | Health & social care | 2020 |
| Mills Holdings Limited | Financial services | 2019 |
| Mills Keep Limited | Professional & scientific | 2013 |
| Mills Local Lettings Limited | Real estate | 2024 |
| Millstream Close Management Company Limited | Households | 1987 |
| Milo Limited | Information & communication | 2020 |
| Miltech Group Limited | Wholesale & retail | 2017 |
| Milvus Solutions Ltd | Professional & scientific | 2026 |
| Mima Analytics Limited | Information & communication | 2022 |
| Minack House Limited | Information & communication | 2020 |
| Mind & Co. Enterprises Limited | Professional & scientific | 2019 |