| Market Field Management Company Limited | Households | 1990 |
| Marlborough Road Wroughton (Swindon) Management Company Limited | Households | 2021 |
| Marnel Park (Basingstoke) Management Company Limited | Households | 2007 |
| Marnel Park Two (Basingstoke) Management Company Limited | Households | 2008 |
| Marshall GAS Heating and Plumbing Ltd | Construction | 2019 |
| Marston Fields (Marston Moretaine) Management Company Limited | Households | 2018 |
| Marston Grange Management Company Limited | Households | 2013 |
| Martello Park (Felixstowe) Residents Management Company Limited | Households | 2012 |
| Martin Industries (Services) Limited | Extraterritorial | 2015 |
| Martin Industries Limited | Manufacturing | 2005 |
| Martindale Place (Southwater) Management Company Limited | Households | 2013 |
| Martineau Court Management (Newbury) Limited | Administrative & support | 2008 |
| Martineau Gardens Harborne Management Company Limited | Households | 2015 |
| Martlesham (Bloor Homes) Management Company Limited | Real estate | 2014 |
| Martletts (Widford) Limited | Households | 2018 |
| Mary Noble Guild Limited | Professional & scientific | 2007 |
| MAS Salons Ltd | Manufacturing | 2023 |
| Mascalls Park Management Company Limited | Households | 2015 |
| Mason's View Management Company Limited | Households | 2004 |
| Matador Enterprises Limited | Manufacturing | 2001 |
| Matador Models Limited | Wholesale & retail | 2021 |
| Matchmaker CNC Ltd | Wholesale & retail | 2025 |
| Mathews Masonry Limited | Construction | 2019 |
| Mathews Property Limited | Real estate | 2020 |
| Matthew Court RTM Company Limited | Real estate | 2013 |
| Mawcott & Sons Ltd | Transport & logistics | 2019 |
| Maybush Fields Management Company Limited | Households | 2017 |
| Mayfield Gardens Management Company Limited | Households | 2018 |
| Mayflower Green (Saxmundham) Residents Company Limited | Households | 2013 |
| Mayhew Gardens (Plympton) Management Company Limited | Households | 2019 |
| Mays Close Management Company Limited | Real estate | 2008 |
| Mays Osteopathy and Bodywork Limited | Health & social care | 2013 |
| MBA Architecture Limited | Professional & scientific | 2017 |
| Mbos Commercial Windscreens Ltd | Construction | 2025 |
| MC Clinical Ltd | Health & social care | 2024 |
| MCJ Courier Services Ltd | Transport & logistics | 2025 |
| Mcom Telecom Limited | Information & communication | 2018 |
| Mead Fields Phase 2 (Leasehold Apartments) Management Company Limited | Households | 2021 |
| Meadow Close Management Company Limited | Households | 2005 |
| Meadow Rise (Braintree) Management Company Limited | Households | 2018 |
| Meadow Rise (Lydney) Management Limited | Households | 2014 |
| Meadow View (Redditch) Resident Management Company Limited | Households | 2018 |
| Meadowbank (Baldwins Gate) Management Company Limited | Extraterritorial | 2017 |
| Meadowbrook (Callington) Management Company Ltd | Households | 2019 |
| Meadowburne Place (Willingdon) Management Company Limited | Households | 2020 |
| Meadows View Residents Management Company Limited | Households | 2015 |
| MED - Aware Limited | Health & social care | 2006 |
| Medi - State Limited | Health & social care | 2006 |
| Medina Diglis Water Management Company Limited | Households | 2006 |
| Medley Court (Exeter) Management NO 2 Limited | Households | 2004 |
| Medley Court (Exeter) Management NO 4 Limited | Households | 2004 |
| Meldan Properties Limited | Construction | 1964 |
| Melly (Southampton 1991) Limited | Administrative & support | 1990 |
| Menear Meadows Amenity Management Company Limited | Households | 2014 |
| Meon Way Gardens Management Company Limited | Households | 2020 |
| Merchants Quay (Portishead) Management Company Limited | Households | 2011 |
| Merchants Walk Cullompton Management Company Limited | Households | 2007 |
| Mercians Place Management Company Limited | Households | 2018 |
| Mercury Bay Properties Limited | Real estate | 2019 |
| Mercury Mansions Limited | Real estate | 2017 |
| Meridien END (Peacehaven) Management Company Limited | Households | 2010 |
| Merlin (Bradley Stoke) Management Company Limited | Households | 1989 |
| Merrick J Limited | Wholesale & retail | 2018 |
| Merrydown Village Residents Ltd | Households | 2016 |
| Mertoch Leat Management Company Ltd | Households | 2017 |
| Meta Research Engine Ltd | Administrative & support | 2016 |
| Meta Social Housing Limited | Real estate | 2025 |
| Mgps Commercial Ltd | Professional & scientific | 2017 |
| Mhcable Holdings Limited | Financial services | 2016 |
| Middlebridge Management Ltd. | Households | 1998 |
| Milbury Reach Management Company Limited | Households | 2012 |
| Milcliff Court Limited | Real estate | 1988 |
| Mill Brook Place (East Grinstead) Residents Management Company Limited | Households | 2011 |
| Mill Court (Alvechurch) Estate Management Limited | Households | 2006 |
| Mill Farming LLP | | 2020 |
| Mill Green (Wheatley) Management Company Limited | Households | 2016 |
| Millbay Estate Management Company Limited | Professional & scientific | 2007 |
| Millbrook Holly Management Company Limited | Households | 2004 |
| Millbrook Meadows Amenity Management Company Limited | Households | 2008 |
| Millbrook Park (Inglis Point) Management Company Limited | Households | 2015 |
| Millbrook Park (Mill Hill) Management Company Limited | Households | 2013 |
| Millers Wharf (Solihull) Management Company Limited | Households | 2005 |
| Millwood Park (Hailsham) Residents Management Company Limited | Households | 2018 |
| Milton House RTM Company Limited | Households | 2008 |
| Milton Manor RTM Company Limited | Households | 2024 |
| Milton Mews (New Milton) Management Company Limited | Households | 2017 |
| Milton Road Investments Limited | Real estate | 1960 |
| Minerva Walk Management Company Limited | Households | 2006 |
| Minford Gardens (Freehold) Limited | Extraterritorial | 2020 |
| Mistletoe House Management Company Limited | Households | 2001 |
| Mistley (Newlands Park) Management Company Limited | Households | 2021 |
| Mitton Grange Management Company Limited | Households | 2022 |
| MJ Aerospace Ltd | Professional & scientific | 2009 |
| MJ Gibbons Financial Planning Ltd | Professional & scientific | 2026 |
| MJC GAS Works Limited | Energy | 2025 |
| MJT Painting Limited | Construction | 2009 |
| MKH Engineering & Motorsport Limited | Manufacturing | 2018 |
| MNS Group Ltd | Wholesale & retail | 2020 |
| Mobile Zone New Milton Ltd | Wholesale & retail | 2025 |
| Monachus ROW (Hartley Wintney) Management Company Limited | Households | 2015 |