| Mandezu Ltd | Transport & logistics | 2015 |
| Mandici Capital Ltd | Real estate | 2019 |
| Mandici Construct Ltd | Construction | 2017 |
| Mandix Ltd | Financial services | 2019 |
| Mane Utility Ltd | Construction | 2021 |
| Mangodilla Limited | Professional & scientific | 2025 |
| Manicomio Limited | Hospitality | 2000 |
| Manish Desai Investments Limited | Real estate | 2017 |
| Manish Desai Medical Services Limited | Health & social care | 2015 |
| Maniyagems Limited | Manufacturing | 2025 |
| Manjeet Infosys Ltd | Information & communication | 2019 |
| Manmade Web Limited | Information & communication | 1998 |
| Mann TAN Ltd | Public administration | 2019 |
| Manocha Enterprise Limited | Wholesale & retail | 2021 |
| Manocha Property Holdings Limited | Other services | 2016 |
| Manolis Group Ltd | Construction | 2020 |
| Manor Estate Cleaning Ltd | Administrative & support | 2020 |
| Mansfield Place Management Co Ltd | Real estate | 2013 |
| Mansfield Roderick Limited | Professional & scientific | 2023 |
| Mansheen Ltd | Wholesale & retail | 2022 |
| Mansoor Electrical Installation Ltd | Construction | 2024 |
| Manta & Alex Ltd. | Construction | 2007 |
| Manta UK Limited | Construction | 2009 |
| Manticore Limited | Real estate | 2023 |
| Mantle Ministries International | Other services | 2019 |
| Mantoo Edgware Ltd | Hospitality | 2024 |
| Manzel Properties Ltd | Real estate | 2024 |
| MAP & Co Construction Ltd | Construction | 2026 |
| Mapas Services Ltd | Administrative & support | 2026 |
| Mapburn Limited | Professional & scientific | 2024 |
| Maple Homes (1 Wesley Walk) Limited | Construction | 2017 |
| Maple Homes (11A High Street) Ltd | Construction | 2014 |
| Maple Homes (5 Thames Street) Ltd | Construction | 2015 |
| Maple Homes (Holdings) Ltd | Construction | 2014 |
| Mapnet Limited | Administrative & support | 2012 |
| Mapogo Records Ltd | Information & communication | 2021 |
| Mappamundi Architects Limited | Professional & scientific | 2005 |
| Mapsat Limited | Real estate | 2021 |
| MAR & SOL Ltd | Real estate | 2024 |
| Marble Exotic Ltd | Construction | 2025 |
| Marc Citron Ltd | Administrative & support | 2010 |
| March SIX Limited | Financial services | 2019 |
| Marco Polo Import & Export Limited | Professional & scientific | 2021 |
| Marcostech Ltd | Information & communication | 2026 |
| Margin Curve Ltd | Professional & scientific | 2022 |
| Margin Trade Ltd | Wholesale & retail | 2021 |
| Marhaba Kabul Ltd | Hospitality | 2026 |
| Maria Vrachni Ltd | Information & communication | 2018 |
| Maria's Services Limited | Health & social care | 2017 |
| Marikon Ltd | Professional & scientific | 2022 |
| Marini Enterprises Limited | Professional & scientific | 2023 |
| Mario MB Ltd | Construction | 2018 |
| Marion Group Limited | Construction | 2023 |
| Marius a Ltd | Construction | 2015 |
| Mark Baum Enterprises Ltd | Other services | 2024 |
| Mark Coward Consulting Limited | Professional & scientific | 2025 |
| Mark Sparks Ltd | Construction | 2014 |
| Marked Estates Limited | Other services | 2023 |
| Market Connectors Ltd | Wholesale & retail | 2024 |
| Market Makers Investments Limited | Real estate | 2006 |
| Marketcase Ltd | Information & communication | 2019 |
| Marketing Sciences Limited | Professional & scientific | 2023 |
| Marley Investment Holdings Ltd | Real estate | 2026 |
| Marlox Holdings Ltd | Wholesale & retail | 2022 |
| Marluc Construction Ltd | Construction | 2019 |
| Marn Limited | Other services | 2006 |
| Marnc Limited | Real estate | 2016 |
| Marnin Limited | Real estate | 2024 |
| Maro Effects Ltd | Information & communication | 2025 |
| Marom Ltd | Construction | 2021 |
| Marpo Limited | Construction | 2024 |
| Marquesa Management Services Limited | Professional & scientific | 1997 |
| Marrant Securities Limited | Households | 1977 |
| Marrwell Ltd | Professional & scientific | 2025 |
| Marrygold Limited | Real estate | 2017 |
| Marsh Lane (Stanmore) Freehold Limited | Financial services | 2017 |
| Marsh Lane (Stanmore) Management Limited | Households | 1982 |
| Marshal's Court Management Company Limited | Households | 1990 |
| Marshalls Brickwork Ltd | Construction | 2021 |
| Marson Tret Technology Solutions Limited | Information & communication | 2019 |
| Mart Informatica Limited | Information & communication | 2025 |
| Martin Chilton Associates Limited | Extraterritorial | 1973 |
| Martin Trans Ltd | Transport & logistics | 2018 |
| Martiniex Limited | Professional & scientific | 2013 |
| Martram Solutions Ltd | Professional & scientific | 2015 |
| Martyn Building Ltd | Construction | 2022 |
| Marutinandan Wholesale Ltd | Wholesale & retail | 2026 |
| MARVA3 Limited | Professional & scientific | 2017 |
| Marvellous Dwellings Limited | Real estate | 2020 |
| Marvina Company Limited | Construction | 2017 |
| Mary Care Properties Limited | Real estate | 2025 |
| Mary Food & Drinks Ltd | Hospitality | 2023 |
| Mary-Ana Cleaning Ltd | Administrative & support | 2020 |
| Maryland Chicken Ltd | Hospitality | 2026 |
| Marylebone Vegetarian Restaurants Limited | Financial services | 2023 |
| Marymar Construction Ltd | Construction | 2016 |
| MAS Clinical Services Ltd | Other services | 2024 |
| MAS Retail Services Ltd | Wholesale & retail | 2026 |
| Masala Bowl Limited | Hospitality | 2020 |
| Mascarenhas Freehold Limited | Households | 2021 |