| Luktom Trading Limited | Transport & logistics | 1975 |
| Lullaloop Limited | Administrative & support | 2021 |
| Luminous Consultancy Limited | Professional & scientific | 2005 |
| Luxury Homes Overseas Limited | Real estate | 2007 |
| Lymington Golf Centre Limited | Arts & recreation | 2002 |
| Lymington Marina Limited | Arts & recreation | 1965 |
| Lymington Recycling Company Limited | Wholesale & retail | 2007 |
| Lymington Test Centre Limited | Wholesale & retail | 2007 |
| Lymington Yacht Haven Limited | Arts & recreation | 1973 |
| Lynchford Tyres Ltd | Manufacturing | 2003 |
| M & J Limousines Limited | Professional & scientific | 2005 |
| M & K Autobody Limited | Wholesale & retail | 2005 |
| M & L Page Construction Ltd | Construction | 2004 |
| M D Technical Services Limited | Professional & scientific | 2001 |
| M G Automation Limited | Manufacturing | 1994 |
| M G M Consultants Limited | Professional & scientific | 1997 |
| M H Bookkeeping Services Ltd | Professional & scientific | 2003 |
| M J Hooper Ltd | Manufacturing | 2003 |
| M L (UK) Limited | Manufacturing | 2002 |
| M M Tilmuth Ltd | Construction | 2019 |
| M. & M. Handling Limited | | 1974 |
| M.& K.Office Services Limited | | 1971 |
| M.A.S. Motorist Centre Limited | Wholesale & retail | 1988 |
| Macqueen International Insurance Brokers Limited | Financial services | 2002 |
| Macropolitan Limited | Administrative & support | 2005 |
| Maddy’S Mark | Other services | 2022 |
| Magdala Court Management Company Limited | Households | 2004 |
| Mailmax Limited | Professional & scientific | 2004 |
| Majorleaf Limited | Wholesale & retail | 1984 |
| Management Innovation Services Limited | Information & communication | 2007 |
| Managing Development Limited | Professional & scientific | 1998 |
| Manakau U.K. Limited | Information & communication | 2023 |
| Manchip Construction Limited | Construction | 2005 |
| Manhattan Enterprises Limited | Information & communication | 2001 |
| Manor Road Nursery Limited | Agriculture & fishing | 1984 |
| Marbow Limited | Wholesale & retail | 1984 |
| Marine Ropes International Limited | Manufacturing | 1999 |
| Mark 1 Double Glazing Limited | Professional & scientific | 1999 |
| Mark a. Ball Fencing and Landscaping Limited | Arts & recreation | 1989 |
| Mark Cooper Limited | Construction | 2002 |
| Mark Hammond Limited | Construction | 1998 |
| Marketing Connections International Ltd | Professional & scientific | 1996 |
| Marketing Solutions International Ltd. | | 1997 |
| Marmalade (UK) Limited | Information & communication | 2004 |
| Marshall Havard Limited | Professional & scientific | 1994 |
| Martin Back Carpentry Limited | Construction | 2003 |
| Martin Jackson Limited | Information & communication | 1997 |
| Masimo Europe Limited | Administrative & support | 2004 |
| Matt Dunkley Music Limited | Arts & recreation | 2008 |
| Matthew Monaghan Limited | Construction | 2019 |
| Matwood Ltd | Professional & scientific | 2024 |
| Mauve Limited | Extraterritorial | 2006 |
| Mauvica Limited | Health & social care | 2013 |
| Maxlogic I.T. Limited | Information & communication | 2000 |
| MAY & Scofield Limited | Manufacturing | 1992 |
| MAY Developments Limited | Construction | 1987 |
| Mayfair Estates Property Investment (MAC) Limited | Real estate | 2022 |
| Mayfair Estates Property Investment Limited | Real estate | 1996 |
| Mayfield Garage Ltd | Wholesale & retail | 2003 |
| Mayhill Motor Company Limited | Wholesale & retail | 2007 |
| Mayville High School Limited | Education | 1961 |
| MB Cabling Solutions Limited | Information & communication | 2013 |
| MC Tilers Limited | Construction | 2006 |
| Mcannor Property Services Ltd | Real estate | 2017 |
| Mckm Management Ltd | Professional & scientific | 2013 |
| Mcleman Forklift Services Limited | Extraterritorial | 1977 |
| MCR Building Services Limited | Construction | 2003 |
| MDA Satconn UK Ltd. | Information & communication | 2016 |
| MDL Pipework & Fabrications Limited | Manufacturing | 2007 |
| Meadowland Properties Limited | Construction | 2005 |
| Meadowtec Associates Limited | Information & communication | 1998 |
| Mebo Comms Limited | Information & communication | 2000 |
| Mebo Communications Limited | Information & communication | 2000 |
| Mebo Limited | Information & communication | 2000 |
| Medaire Limited | Wholesale & retail | 2002 |
| Media Attention Limited | Information & communication | 1998 |
| Mediaxtreme Limited | Professional & scientific | 2002 |
| Melaxe Limited | Administrative & support | 1987 |
| Mellor's Property Holding Company Limited | Real estate | 1992 |
| Mentat Limited | Information & communication | 2003 |
| Merchant Marketing Group Ltd | Professional & scientific | 1982 |
| Merchant Packaging Data Limited | Information & communication | 2025 |
| Mercury (PMC) Limited | Extraterritorial | 2007 |
| Merdon Limited | Construction | 2003 |
| Merrydown Consultants Limited | Professional & scientific | 2004 |
| Mestling Limited | Professional & scientific | 1999 |
| Metari Limited | Professional & scientific | 2000 |
| Metcase Enclosures Limited | Manufacturing | 2004 |
| Methuselah Properties Limited | Real estate | 2003 |
| Meyer Developments Ltd | Manufacturing | 1988 |
| MFI & Co Investments Ltd | Real estate | 2020 |
| Miami Sunbeds Limited | Administrative & support | 2002 |
| Micheldever Group Limited | Professional & scientific | 2005 |
| Micheter Limited | Professional & scientific | 2006 |
| Micro Plas Mouldings Ltd | Manufacturing | 2005 |
| Micro-Moulding Limited | | 1988 |
| Micron Maintenance Limited | Information & communication | 2001 |
| Micron Talk Limited | Information & communication | 2007 |
| Mid-Hants Railway Limited | Administrative & support | 1973 |
| Midlington House Residents Association Limited | Real estate | 1972 |