| Lindair Investments Limited | Real estate | 2007 |
| Lingo Europe Limited | Education | 2004 |
| Litrezone Limited | Households | 1986 |
| Live and LET Live Limited | Administrative & support | 2002 |
| Lockygen Holdings Limited | Financial services | 2018 |
| Locomatrix Limited | Information & communication | 2007 |
| Lodestar Cleaning Contracts Limited | Administrative & support | 1980 |
| London Amore Skin LAB Ltd | Wholesale & retail | 2025 |
| Lonebay Limited | Construction | 2007 |
| Lovebirds Studio Ltd | Wholesale & retail | 2023 |
| Lower Claverham Farm Limited | Agriculture & fishing | 2002 |
| Lumbertubs Management Limited | Real estate | 2005 |
| Lynnik Property Services Limited | Extraterritorial | 2003 |
| Lyntec Security Systems Limited | | 1991 |
| M Appleton Plumbing & Heating Limited | Construction | 2003 |
| M. &. K. Contractors Limited | Construction | 1983 |
| M. K. Next Limited | Construction | 1996 |
| M.F.Fennell and Company Limited | Wholesale & retail | 1932 |
| M.J. Zara Associates Limited | Professional & scientific | 1999 |
| M.N.S. Music Limited | Arts & recreation | 1986 |
| M.R.G Decorating & Property Maintenance Limited | Other services | 2007 |
| M.S.B. Interiors Ltd | Construction | 2006 |
| Macguru Limited | Information & communication | 2002 |
| Mackay Products (Bristol) Limited | Construction | 1960 |
| Maclean Heating Limited | Wholesale & retail | 2007 |
| MAD4MOBILES (Maidstone) Limited | Wholesale & retail | 2006 |
| Made in Hastings Limited | Wholesale & retail | 2004 |
| Madison Gold Ltd | Real estate | 2023 |
| Madreselva Limited | Information & communication | 1995 |
| Madrigal Mansions Limited | Households | 1998 |
| MAF Surveying Services Limited | Professional & scientific | 2001 |
| Maffco Ltd | Information & communication | 2005 |
| Magnum Opus Developments Limited | Real estate | 1999 |
| Main Systems Distributors Limited | Professional & scientific | 1977 |
| Main Systems Limited | Manufacturing | 1971 |
| Main Systems Processes Limited | Professional & scientific | 1975 |
| Main Systems Services Limited | Professional & scientific | 1974 |
| Mainway Designs Limited | | 1987 |
| Majestic Barbers Ltd | Other services | 2026 |
| Majic Limited | Administrative & support | 2006 |
| Malcolm Clear Limited | Real estate | 1995 |
| Maldwyn Bowden International Sales Limited | Administrative & support | 1979 |
| Mamleo Limited | | 1982 |
| Management Consultancy Services Limited | Professional & scientific | 2005 |
| Management Inspirations Limited | Professional & scientific | 2004 |
| Mane Attraction Limited | Other services | 2002 |
| Manningtons Ltd | Administrative & support | 2003 |
| Mansell Mctaggart Newick Ltd | Real estate | 2007 |
| Manywares Limited | Hospitality | 1976 |
| Marchants Garages (Tunbridge Wells) Limited | Wholesale & retail | 1946 |
| Marconite Residents Company Limited | Households | 1987 |
| Marcucci Limited | Real estate | 2000 |
| Marevista Limited | Administrative & support | 2016 |
| Marine Property Investments (Brighton) Limited | Real estate | 1939 |
| Mark Fernell Limited | Other services | 2002 |
| Mark Johnston Ltd | Arts & recreation | 2006 |
| Mark Mantey Ltd. | Wholesale & retail | 1988 |
| Mark Soper Opticians Ltd | Wholesale & retail | 2005 |
| Markies Antiques Limited | Wholesale & retail | 2003 |
| Marmyte Management Limited | Households | 1999 |
| Marsden Court (Telscombe Cliffs) Residents Association Limited | Hospitality | 1974 |
| Marshall Hoad Electrical Limited | Construction | 2006 |
| Marshflex Ltd | Professional & scientific | 2003 |
| Martello Court Properties Limited | Households | 1992 |
| Martello Mews Flats Management Limited | Households | 1999 |
| Martin D Johnson Antiques Limited | Wholesale & retail | 2006 |
| Martin Pryke Tailoring Limited | Wholesale & retail | 2004 |
| Martin Szczerbicki Associates Limited | Professional & scientific | 2003 |
| MAS Systems Limited | Construction | 1998 |
| Maskell Heating Services Limited | Administrative & support | 2000 |
| Massey Group Limited | Real estate | 1974 |
| Massey Property Services Limited | Real estate | 1998 |
| Master Parts (UK) Limited | Wholesale & retail | 1993 |
| Matra Carpentry Limited | Construction | 2007 |
| Matterhorn Capital Mayfair NO.1 LP | | 2007 |
| Mavrap Limited | Real estate | 2002 |
| MAX5 Ltd | Administrative & support | 2017 |
| Maxima Homes Limited | Construction | 2004 |
| MAY (Imports) Limited | Administrative & support | 1999 |
| Mayfair Property Renovations Limited | Construction | 2006 |
| Mayfair RE Limited | Construction | 2005 |
| Mayfield School Services Ltd. | Wholesale & retail | 1992 |
| MB Derivatives Limited | Financial services | 2007 |
| Mcconnel Construction S.E. Limited | Construction | 2002 |
| Mcfl Service Charge Limited | Households | 2025 |
| Mcintyre Developments Limited | Construction | 2007 |
| Medfield Property Co (Putney) Limited | Extraterritorial | 1963 |
| Medina Gina Katiuska Limited | Real estate | 2024 |
| Medwest Investments Limited | Real estate | 2003 |
| Melward Plays Limited | Extraterritorial | 1949 |
| Memtis Limited | Construction | 2004 |
| Merchant & General Estates Limited | Construction | 2001 |
| Mercury Minibuses Limited | Transport & logistics | 2004 |
| Meridian Marquees Limited | Administrative & support | 2001 |
| Mersell Management Limited | Real estate | 2002 |
| Mesterdene Limited | Administrative & support | 2001 |
| Metamorphosis Interiors Limited | Other services | 1964 |
| Metropolitan Insurance Bureau Ltd | Professional & scientific | 1930 |
| MEY George Hair Ltd | Other services | 2023 |
| MGP Plant Limited | Professional & scientific | 1999 |