| Lynsey Smith Ltd | Health & social care | 2022 |
| Lynx Sports Management Limited | Professional & scientific | 2005 |
| Lyrical Games Limited | Hospitality | 2020 |
| Lyrical Investments Limited | Construction | 2021 |
| LYS Management Ltd | Professional & scientific | 2023 |
| M & J Air Conditioning Limited | Construction | 2006 |
| M & M Automotive Historic Limited | Wholesale & retail | 2016 |
| M and D Engineering Solutions Ltd | Professional & scientific | 2016 |
| M Custom Signage Solutions Ltd | Professional & scientific | 2025 |
| M Moody Welding Ltd | Professional & scientific | 2011 |
| M W V Ltd | Professional & scientific | 2016 |
| M.J.D. Sea Expeditions Limited | Transport & logistics | 2019 |
| Mabtek Construction Consultancy Ltd | Professional & scientific | 2020 |
| Macalister Elliott & Partners Limited | Professional & scientific | 1977 |
| Machetti Limited | Transport & logistics | 2025 |
| Madison Property Developments Limited | Real estate | 2006 |
| Madison Residential Property Limited | Real estate | 2006 |
| Madisons Interiors Limited | Construction | 2007 |
| Maestro Classics Limited | Arts & recreation | 2010 |
| Magnolia Landscaping Limited | Administrative & support | 2021 |
| Mahjong Ltd | Real estate | 2013 |
| Mainland Developments Limited | Real estate | 1998 |
| Maishem Limited | Transport & logistics | 2017 |
| Maitland Investments Limited | Real estate | 1971 |
| Malbie Business Services Ltd | Administrative & support | 2017 |
| Malcolm Mckeon Yacht Design Limited | Professional & scientific | 2012 |
| Malcolm Mckeon Yachts Limited | Extraterritorial | 2012 |
| Malfatti Ltd | Hospitality | 2022 |
| Mamaro Ltd | Manufacturing | 2023 |
| Manawa London Limited | Information & communication | 2015 |
| Mannequin Mouth Ltd | Information & communication | 2024 |
| Mansoori Heights Ltd. | Hospitality | 2017 |
| Maranta Limited | Professional & scientific | 2015 |
| Marcham Associates Ltd | Information & communication | 2023 |
| Marie-Anne Rose Limited | Professional & scientific | 2002 |
| Marine Game Ltd | Financial services | 2021 |
| Marine IP Limited | Arts & recreation | 2014 |
| Maritime Projects Ltd | Professional & scientific | 2023 |
| Mark Berryman Design Limited | Professional & scientific | 2007 |
| Mark Cutler Auto Engineering Limited | Wholesale & retail | 2014 |
| Mark Whiteley Design Limited | Professional & scientific | 2014 |
| Markin Finance Limited | Financial services | 1968 |
| Markwells Property Management Ltd | Households | 2026 |
| Marquis Professional Limited | Real estate | 1998 |
| Marssa Ltd | Real estate | 2019 |
| Marydale Residents Management Company Limited | Households | 1972 |
| Matatas 3 Cuisine Limited | Hospitality | 2025 |
| Materials Direct Limited | Other services | 2014 |
| Matford Farm Limited | Agriculture & fishing | 2018 |
| Mathewson and Sons Metals Ltd | Manufacturing | 2026 |
| Matt Roseveare Media Ltd | Information & communication | 2026 |
| Matthew Clarke Ltd. | Professional & scientific | 2021 |
| Matthew Palmer Limited | Construction | 2002 |
| Matthews Coastal Properties Ltd | Construction | 2020 |
| MAX Innovation Limited | Wholesale & retail | 2023 |
| Maxuna Ltd | Construction | 2026 |
| Maxwell Hamilton Lymington Ltd | Extraterritorial | 2017 |
| Mccafferty Design Limited | Professional & scientific | 2012 |
| Mcclounan Consulting Ltd | Other services | 2021 |
| MCE Roofing Ltd | Construction | 2023 |
| MCF Brickwork Limited | Construction | 2019 |
| Mcmanus Design Ltd | Professional & scientific | 2014 |
| MD Developments (New Forest) Limited | Construction | 2008 |
| MDM Contemporary Limited | Administrative & support | 2007 |
| Mead Wolfe Limited | Other services | 2024 |
| Meadowbrook Property Ltd | Real estate | 2026 |
| Mechelecsoft Ltd | Information & communication | 2024 |
| Memoryworks Hampshire CIC | Health & social care | 2018 |
| Meow 1215 Ltd | Education | 2023 |
| Meraki. Ironmongery Ltd | Wholesale & retail | 2026 |
| Metal by Design Services Limited | Manufacturing | 2018 |
| Metavoice Ltd | Information & communication | 2022 |
| Mezmerize Productions Limited | Information & communication | 2004 |
| MG Farriers Ltd | Other services | 2024 |
| Mgchiropractic Ltd | Health & social care | 2026 |
| Michael Jordan Estates Limited | Hospitality | 2019 |
| Michael Turner Studios Limited | Arts & recreation | 2012 |
| Microtech 96 Limited | Manufacturing | 2005 |
| Midak Engineering Ltd | Mining & quarrying | 2018 |
| Middlebere Limited | Construction | 2009 |
| Midnight Blue Coffee Limited | Wholesale & retail | 2018 |
| Midori Sustainability Ltd | Professional & scientific | 2022 |
| Mighty Property Ltd | Real estate | 2020 |
| Migrant JOB Search Limited | Administrative & support | 2021 |
| Mike Fuhr Advisory Services Ltd | Professional & scientific | 2012 |
| Mike Walsh Pressure Vessels Limited | | 1983 |
| Mildirect Ltd | Extraterritorial | 2024 |
| Milford Court Residents Association Limited | Real estate | 1973 |
| Milford House Management (Hampshire) Limited | Households | 1974 |
| Milford Marine Ltd | Wholesale & retail | 2023 |
| Milford Millennium Shop Limited | Wholesale & retail | 2014 |
| Milford-On-Sea Church of England Primary School Academy Trust | Education | 2013 |
| Military Precision Ltd | Construction | 2021 |
| Millennium Business Consultants Ltd | Professional & scientific | 2020 |
| Millmead Holdings Limited | Real estate | 2006 |
| Minber Developments Ltd. | Extraterritorial | 1992 |
| Mindsenseability Ltd | Health & social care | 2016 |
| Minute Details Limited | Professional & scientific | 2021 |
| Miranda Investments Limited | Real estate | 2013 |
| Mirrormakeover Limited | Extraterritorial | 2021 |