| Lumara Care Ltd | Health & social care | 2026 |
| Luxborough Leisure Limited | Arts & recreation | 2020 |
| Luxro Ltd | Transport & logistics | 2026 |
| LW Building & Construction Ltd | Construction | 2016 |
| Lycett Place Development Limited | Construction | 2015 |
| Lyle JV Holdings Limited | Financial services | 2016 |
| L’Eree Group Ltd | Construction | 2025 |
| M E Property Investments Limited | Real estate | 2013 |
| M Grieves Properties Limited | Real estate | 2015 |
| M H S Electricals Ltd | Construction | 2014 |
| M S M Developers Limited | Construction | 2009 |
| M Samra Construction Limited | Construction | 2024 |
| M&E Search Limited | Administrative & support | 2020 |
| M.Lee Building Services Limited | Construction | 2011 |
| M.R.T. Limited | Construction | 1998 |
| M1 Properties Ltd | Real estate | 2025 |
| M4 Supplies Ltd | Wholesale & retail | 2015 |
| Macarty’S Mobile Tyres Ltd | Manufacturing | 2023 |
| Mack Business Services Limited | Professional & scientific | 2002 |
| Mack Monroe Limited | Construction | 2024 |
| Mackie Family Investment Co Limited | Real estate | 2021 |
| Magic Services Ltd | Construction | 2026 |
| Magnavision Ltd | Information & communication | 2016 |
| Mainline Contractors & Co Limited | Construction | 2012 |
| Mainline Contractors (Eltham) Limited | Construction | 2006 |
| Maitland Engineering Limited | Construction | 2009 |
| Malvi Consultancy Limited | Professional & scientific | 2017 |
| Malyons Construction Ltd | Construction | 2020 |
| Malyons Superstore Ltd | Wholesale & retail | 2024 |
| Mamalisa Shoes Limited | Wholesale & retail | 2016 |
| Mamorgan Properties Ltd | Real estate | 2026 |
| Mamt Projects Limited | Professional & scientific | 2014 |
| Manor Roofing and Building Contractors Ltd | Construction | 2026 |
| Maple Farm Limited | Real estate | 2007 |
| Mapped OUT Media Limited | Professional & scientific | 2023 |
| Mariglass Ltd | Construction | 2015 |
| Marinov Electrical Limited | Construction | 2003 |
| Marisa Consultancy Limited | Information & communication | 2023 |
| Marisa Residences Ltd | Extraterritorial | 2002 |
| Maritime Applications Limited | Information & communication | 2013 |
| Mark Beckley GAS Services Limited | Construction | 2003 |
| Mark Nelson 1ST Class Roofing Services Limited | Construction | 2007 |
| Marke Property Services Limited | Construction | 2016 |
| Martin Arnold Developments Limited | Construction | 2020 |
| Martyn.Proficient.Services Limited | Construction | 2018 |
| Mary Philip Limited | Health & social care | 2019 |
| Maryland Gardens (Management) Limited | Households | 1968 |
| MAS Construction Ltd | Construction | 2022 |
| Masi Medical Ltd | Health & social care | 2019 |
| Mastermind Real Estate Group Ltd | Real estate | 2019 |
| Materia Group Limited | Professional & scientific | 2017 |
| Material Resources Limited | Construction | 1994 |
| Materials Resources Southern Limited | Construction | 2020 |
| Materiatech Limited | Professional & scientific | 2017 |
| Mathu Housing Ltd | Real estate | 2022 |
| Mathu Property Ltd | Real estate | 2019 |
| Mathu Retail Ltd | Wholesale & retail | 2022 |
| Matt Wainwright Ltd | Information & communication | 2011 |
| Mattcorp Ltd | Information & communication | 2016 |
| Matter Recruit Limited | Administrative & support | 2025 |
| Mavelstone Building Services Ltd | Construction | 2022 |
| Maxwell Valentine Estates Limited | Real estate | 2017 |
| Mayfair Construction Developments Ltd | Manufacturing | 2009 |
| Mayfair Homes (Kent) Ltd | Real estate | 2020 |
| Mayfield Management Limited | Households | 2024 |
| Mayowa Samuels Ltd | Wholesale & retail | 2016 |
| Mazeeds Prized Limited | Health & social care | 2023 |
| MB Event Hire Limited | Administrative & support | 2023 |
| MB Windows Limited | Construction | 2008 |
| Mbpscleaningservices Ltd | Administrative & support | 2024 |
| Mcallister Developments Limited | Construction | 2006 |
| Mccourts Solutions Limited | Professional & scientific | 2021 |
| Mcging Interiors and Buildings Limited | Construction | 2017 |
| Mclaughlin Regulation Services Limited | Professional & scientific | 2026 |
| Mcnair-Wilson Innes & Co Limited | Professional & scientific | 2022 |
| MDN Technology and Services Ltd | Wholesale & retail | 2020 |
| Mdntechuk Ltd | Wholesale & retail | 2024 |
| Me&P Cost Consulting Ltd | Professional & scientific | 2011 |
| ME19 Interior Construction Ltd | Construction | 2020 |
| Meafy Ltd | Wholesale & retail | 2025 |
| Medictainer Limited | Health & social care | 2023 |
| Medilake Limited | Wholesale & retail | 1999 |
| Medlake Homes Limited | Construction | 2014 |
| Medway Group Limited | Professional & scientific | 2000 |
| Meif 5 Green Infrastructure Ventures FE Limited | Financial services | 2019 |
| Meif 5 Green Infrastructure Ventures RE Limited | Financial services | 2019 |
| Melbourne Grove Freehold Ltd | Households | 2019 |
| Menil Limited | Hospitality | 2019 |
| Mercer Lane Care Limited | Health & social care | 2025 |
| Meridian Capital Holdings Limited | Real estate | 2026 |
| Meridian Hospital Company (Holdings) Limited | Administrative & support | 1997 |
| Meridian Hospital Company PLC | Administrative & support | 1997 |
| Merlewood Drive Residents Association Limited | Extraterritorial | 2012 |
| Merlin Industrial Estate Holdings Ltd | Real estate | 2025 |
| Meropo Ltd | Professional & scientific | 2023 |
| Merrisha Gordon Coaching & Consultancy Limited | Professional & scientific | 2021 |
| Messi Bear Limited | Professional & scientific | 2020 |
| Metrix Data Limited | Other services | 2024 |
| Mgref 2 Cooks Bidco Limited | Financial services | 2022 |
| Mgref 2 Cooks Holdings 2 Limited | Financial services | 2025 |