| Mamood Property Ltd | Real estate | 2025 |
| MAN and Beard Ltd | Other services | 2020 |
| MAN O Salwa Ltd | Wholesale & retail | 2021 |
| Mana Developments Limited | Real estate | 2019 |
| Manage.Management Limited | Information & communication | 2025 |
| Managed Self Limited | Information & communication | 2017 |
| Mandarin Maintenance Limited | Households | 2004 |
| Mandells Domestic Appliances LLP | | 2017 |
| Mane Street Ferndown Limited | Other services | 2007 |
| Mangel Global Ltd | Wholesale & retail | 2024 |
| Mango Accounting Ltd | Professional & scientific | 2025 |
| Mango Ignite Limited | Information & communication | 2021 |
| Manington Hall (Bournemouth) Limited | Households | 1966 |
| Manley Wood (Hamworthy) Management Company Limited | Households | 1997 |
| Manna Property Holdings Ltd | Real estate | 2022 |
| Mannin GAS Services Limited | Manufacturing | 2016 |
| Manor Farm Consultancy (Dewlish) Limited | Professional & scientific | 2014 |
| Manor House (Bournemouth) RTM Company Limited | Households | 2006 |
| Manor Lodge (Bournemouth) Management Co. Ltd. | Households | 2003 |
| Manor Pain Ltd | Health & social care | 2015 |
| Manorah Services Ltd | Health & social care | 2011 |
| Manorbourne Management Co Ltd | Real estate | 2002 |
| Manorial Services Ltd | Other services | 2020 |
| Mansfield Court (Bournemouth) Management Company Limited | Households | 1989 |
| Manta Risk Consultancy Limited | Professional & scientific | 1999 |
| Manuels&Co Ltd | Hospitality | 2019 |
| Maraben Ltd | Administrative & support | 2021 |
| Maracon Ltd | Mining & quarrying | 2014 |
| Maravi & Wellness Ltd | Wholesale & retail | 2025 |
| Marbar Ltd | Real estate | 2025 |
| Marbella Aesthetics Boscombe Ltd | Other services | 2026 |
| Marbella Aesthetics Ltd | Other services | 2023 |
| Marc of Approval Ltd | Construction | 2015 |
| Marcel T Ltd | Professional & scientific | 2018 |
| March Compliance LLP | | 2004 |
| Marchwood (Freehold 1996) Limited | Households | 1996 |
| Marchwood Management Company Limited | Households | 1971 |
| Marciosdelicacies Ltd | Wholesale & retail | 2022 |
| Marco Glass & Glazing Limited | Manufacturing | 1994 |
| Marcus Media Ltd | Information & communication | 2007 |
| Marele Accountancy CC Ltd | Professional & scientific | 2022 |
| Marele Accountancy Limited | Professional & scientific | 2015 |
| Marele Accountancy OP Ltd | Professional & scientific | 2018 |
| Maremma to Go Ltd | Information & communication | 2026 |
| Mareuse Construction Solutions Ltd | Construction | 2025 |
| Margarets Home Care Services Ltd | Health & social care | 2020 |
| Margit Properties Limited | Construction | 1965 |
| Marguerite Thorpe Limited | Wholesale & retail | 1980 |
| Maria R Ltd | Hospitality | 2025 |
| Mariasmartcars Ltd | Wholesale & retail | 2025 |
| Marina Court (Boscombe) Limited | Real estate | 1967 |
| Marina Court (Highcliffe) Management Company Limited | Households | 1973 |
| Marina Electricals Limited | Construction | 2025 |
| Marine 02 Limited | Households | 2020 |
| Marine Bedding Limited | Extraterritorial | 2015 |
| Marine Carpentry Projects Limited | Manufacturing | 2022 |
| Marine Insulation Services Ltd | Professional & scientific | 2017 |
| Marine Metal Services Limited | Manufacturing | 2010 |
| Marine Survey Tech Ltd | Professional & scientific | 2026 |
| Mariners Gate (Poole) Limited | Real estate | 2004 |
| Mariners Management Company Limited | Households | 1972 |
| Marini Pizza Ltd | Hospitality | 2023 |
| Marithia Limited | Households | 2025 |
| Marivale Projects Ltd | Real estate | 2014 |
| Marjorie Burnett Limited | Real estate | 1963 |
| Mark Colour & Decor Ltd | Construction | 2016 |
| Mark Comms Limited | Information & communication | 2014 |
| Mark Dixon Consultancy Limited | Information & communication | 2014 |
| Mark Fisher(Mans Shop)Limited | Real estate | 1960 |
| Mark Futter Limited | Information & communication | 2010 |
| Mark James Goldsmiths Limited | Wholesale & retail | 2013 |
| Mark ORR Limited | Real estate | 2003 |
| Mark Prentice Heating Ltd | Construction | 2025 |
| Mark Unique Ltd | Wholesale & retail | 2020 |
| Mark Ward Studio Limited | Arts & recreation | 2015 |
| Markate Energy Ltd | Wholesale & retail | 2025 |
| Market Donkey Ltd | Professional & scientific | 2024 |
| Market Position Limited | Financial services | 2004 |
| Market Way Ltd | Transport & logistics | 2025 |
| Marketforces Limited | Professional & scientific | 1989 |
| Marketing for Profits Ltd | Professional & scientific | 1998 |
| Markham Avenue Service Co. Ltd | Households | 2025 |
| Markham Road Management Company Limited | Households | 2012 |
| Markham Ruby ROO Ltd | Wholesale & retail | 2021 |
| Marlands Topco Limited | Financial services | 2023 |
| Marlborough Sterling Investment Group Limited | Financial services | 2016 |
| Marlin Joinery (Dorset) Ltd | Construction | 2013 |
| Marlow Architects Ltd | Professional & scientific | 2021 |
| Marlvict Investment Ltd | Extraterritorial | 2024 |
| Marmaston Investments Ltd | Real estate | 2003 |
| Marmion (Italia) Limited | Hospitality | 2019 |
| Marmion Food Services Limited | Hospitality | 2018 |
| Marmion Jewellers Ltd | Wholesale & retail | 2019 |
| Marmon Ltd | Real estate | 2020 |
| Maronsouth Limited | Administrative & support | 2008 |
| Maros Home Renovations Ltd | Construction | 2024 |
| Maroun's Food Ltd | Hospitality | 2023 |
| Marqueemedia Limited | Manufacturing | 2003 |
| Marquis International Ltd | Wholesale & retail | 2016 |
| Mars Kitchen Ltd | Hospitality | 2025 |