| Lulu Construction Ltd | Construction | 2001 |
| Lulu Properties Ltd | Real estate | 2007 |
| Lunhall Limited | Professional & scientific | 1986 |
| Lupus Leisurewear Limited | | 1983 |
| Lushi Chauffeur Services Ltd | Transport & logistics | 2005 |
| Luvenex Ltd | Manufacturing | 2025 |
| LUX Regulatory Solutions Ltd | Other services | 2018 |
| Luxmi Limited | Wholesale & retail | 2000 |
| Luxurious Holding Ltd | Real estate | 2025 |
| Lynbett Properties Limited | Construction | 1985 |
| Lynx Financial Services Ltd | Financial services | 2006 |
| Lyons Tetley Limited | Extraterritorial | 1962 |
| Lysis Limited | Professional & scientific | 2001 |
| Lytestyle Designs Limited | Manufacturing | 2007 |
| M & E Plumbing and Heating Ltd | Construction | 2007 |
| M & M Business Solutions Limited | Wholesale & retail | 2001 |
| M & N Associates (UK) Ltd | Real estate | 2002 |
| M a Heating & Plumbing Limited | Construction | 2005 |
| M Arts Club Ltd | Arts & recreation | 2013 |
| M Fenton and Partner | | 1989 |
| M J H K Properties Limited | Information & communication | 1999 |
| M J Sear Limited | Construction | 2002 |
| M P R U Developments Limited | Real estate | 2006 |
| M R Land Limited | Administrative & support | 2007 |
| M R Shah & Co Limited | Professional & scientific | 2000 |
| M Rabin & Co Limited | Professional & scientific | 2002 |
| M Sparkling Cleaning Service Limited | Extraterritorial | 2015 |
| M Technologies Limited | Information & communication | 1981 |
| M Y S Property Limited | Real estate | 2015 |
| M&A Building Ltd | Construction | 2018 |
| M&E Majestic Empire Ltd | Manufacturing | 2025 |
| M&T Building & Extensions Services Ltd | Construction | 2014 |
| M. Pegram and Associates Limited | Professional & scientific | 1987 |
| M.C. Electronics Limited | Manufacturing | 1980 |
| M.G. Building Contractors Limited | Construction | 1997 |
| M.L.L.C. Limited | Other services | 1997 |
| M.N.C. Management Ltd | Administrative & support | 1998 |
| M25 Security Systems Limited | Administrative & support | 1994 |
| MA Procurement Ltd | Professional & scientific | 2015 |
| MA9 Limited | Other services | 2009 |
| Mabak Limited | Professional & scientific | 1986 |
| Macco (UK) Ltd | Other services | 2002 |
| MACH23 Ltd | Information & communication | 2013 |
| Machindo Limited | Arts & recreation | 2008 |
| Machine Monitoring Systems Limited | Administrative & support | 1990 |
| Machine Point Limited | Extraterritorial | 1999 |
| Mackenzie Jackson Limited | Professional & scientific | 2012 |
| Mackev Solutions Limited | Wholesale & retail | 2004 |
| Maclean London Limited | Professional & scientific | 2009 |
| Madeira UK Services Limited | Transport & logistics | 2015 |
| Madhu Enterprise Limited | Health & social care | 2024 |
| Madhu's Limited | Hospitality | 2002 |
| Madre Properties Ltd | Construction | 2018 |
| Madre Property Ltd | Real estate | 2024 |
| Maestro Films Limited | Arts & recreation | 2002 |
| Mageida Ltd | Health & social care | 2013 |
| Magitex Ltd | Wholesale & retail | 1995 |
| Magnibuild Ltd | Construction | 2015 |
| Magnifico Travel Limited | Education | 1999 |
| Magnocrest Limited | Wholesale & retail | 1998 |
| Magsonic Limited | Information & communication | 1998 |
| Mahesh Carpentry Services Limited | Construction | 2000 |
| Main AIM Holding Co Limited | Financial services | 2024 |
| Main Event Party Planners Limited | Arts & recreation | 1987 |
| Mainstream Data Limited | Information & communication | 2001 |
| Maison Advisory Group Ltd | Professional & scientific | 2026 |
| MAJ I-D Limited | Information & communication | 2005 |
| Major TOM Limited | Administrative & support | 1998 |
| Majorquest Limited | Real estate | 1997 |
| Makem Scrivener Limited | Real estate | 2007 |
| Maksons Limited | Real estate | 2005 |
| Malar Spice Ltd | Hospitality | 2021 |
| Malcolm Paget Limited | Professional & scientific | 2002 |
| Maldwyn Investments Limited | Real estate | 2001 |
| Malhi Developers Limited | Other services | 1999 |
| Malik Traders Limited | Professional & scientific | 2005 |
| Malmau Property Ltd | Real estate | 2020 |
| MAN Mandir Elders Empowerment Hub Community Interest Company | Health & social care | 2006 |
| Manage UK Ltd. | Real estate | 2003 |
| Mandara Consulting Limited | Information & communication | 2006 |
| Mangelwurzel Limited | Professional & scientific | 2006 |
| Mangia CON Gusto Ltd | Hospitality | 2003 |
| Mango Healthcare Limited | Other services | 2002 |
| Manning & Boyce Accident Repairs Limited | Wholesale & retail | 2001 |
| Manor Bar Ltd | Hospitality | 2018 |
| Manor Chase Connections Limited | Construction | 1998 |
| Mansbridge Estates Limited | Real estate | 2003 |
| Manson Limited | Transport & logistics | 1993 |
| Mantoush Limited | Hospitality | 2021 |
| Manu Pabari Letting Agents Limited | Real estate | 2019 |
| Maplewood Court Residents Association Limited | Households | 2001 |
| MAR System Solutions Ltd. | Information & communication | 2002 |
| Marac International Marketing Limited | Wholesale & retail | 2002 |
| Marc International Limited | Transport & logistics | 1988 |
| Marcel. Enujuba | | 1998 |
| Marchant Consultancy Limited | Administrative & support | 1990 |
| Marcus J Catlin Productions Limited | Information & communication | 2006 |
| Mardondale Limited | | 1979 |
| Marigold Footcare Ltd. | Wholesale & retail | 1984 |
| Mark Hoey | | 1998 |