| Maohub Ltd | Wholesale & retail | 2025 |
| MAP Brands Ltd | Other services | 2025 |
| MAP Electrical (Yorkshire) Ltd | Construction | 2017 |
| MAP Estates Ltd | Real estate | 2002 |
| MAP Financial Planning Ltd | Financial services | 2020 |
| MAP Trading Leeds Ltd | Real estate | 2022 |
| Mapfs Limited | Financial services | 2016 |
| Mapinguari Ltd | Information & communication | 2021 |
| Maple Business Solutions Limited | Professional & scientific | 2008 |
| Maple Green (Hyde Park) Management Company Limited | Real estate | 2017 |
| Maple Park (Wentworth) Limited | Real estate | 2005 |
| Maple Project Solutions Ltd | Professional & scientific | 2013 |
| Maple Surgical Ltd | Health & social care | 2022 |
| Maple Tree Joinery Limited | Construction | 2015 |
| Maple Tree Property Investments Ltd | Real estate | 2021 |
| Maplecode Limited | Information & communication | 2011 |
| Maplecrest Limited | Administrative & support | 2017 |
| Maples and Calder Services Europe Limited | Administrative & support | 2009 |
| Mapleside Property Network Ltd | Real estate | 2023 |
| Maplin Electronics Limited | Wholesale & retail | 1976 |
| Maposa Ltd | Health & social care | 2018 |
| Mapped Civils Limited | Construction | 2024 |
| Mappo's Printing Services Ltd | Manufacturing | 2024 |
| Maqbool Medical Care Ltd | Health & social care | 2024 |
| Maqbool Optometry Ltd | Health & social care | 2019 |
| Maqh Logistics Ltd | Transport & logistics | 2018 |
| MAR Hall Hospitality Limited | Hospitality | 2023 |
| MAR Investments Ltd | Real estate | 2024 |
| Mar-Tex Research Ltd | Professional & scientific | 2010 |
| Mara's Cleaning Ltd | Administrative & support | 2023 |
| Marai Properties Ltd | Real estate | 2022 |
| Maranar Limited | Real estate | 1971 |
| Maranatha Africa Shop Ltd | Wholesale & retail | 2025 |
| Marase Home Ltd | Wholesale & retail | 2026 |
| Marble 4 Life Ltd | Manufacturing | 2004 |
| Marble Arch Assets Ltd | Real estate | 2023 |
| Marble Development Services Ltd | Information & communication | 1992 |
| Marble Run Ltd | Information & communication | 2019 |
| Marbob Ltd | Financial services | 2022 |
| Marcdallimore Media Ltd | Professional & scientific | 2021 |
| Marcel Developments Limited | Real estate | 1983 |
| Marcel Holdings Limited | Financial services | 2024 |
| Marcher Roofing Limited | Construction | 1997 |
| Marchewka Ltd | Information & communication | 2023 |
| Marching OUT Together CIC | Other services | 2024 |
| Marchwiel Properties Limited | Construction | 1960 |
| Marcin Morus Transport Limited | Construction | 2013 |
| Marco & Sons Holdings Ltd | Real estate | 2025 |
| Marco Consultancy Limited | Professional & scientific | 2025 |
| Marco Courier Ltd | Transport & logistics | 2025 |
| Marcu Marius Limited | Transport & logistics | 2025 |
| Marcus Black Design Limited | Wholesale & retail | 2019 |
| Marcus Developments Limited | Construction | 2020 |
| Marcus Marks Estates Ltd | Real estate | 2019 |
| Marcus Tech Consulting Ltd | Wholesale & retail | 2021 |
| Marden Properties Ltd | Real estate | 2025 |
| Mardon Asset Consultancy Ltd | Professional & scientific | 2017 |
| Mardy Cat Ltd | Information & communication | 2025 |
| Mareia Limited | Information & communication | 2015 |
| Marein Ltd | Real estate | 2022 |
| Marek Tkaczyk Ltd | Transport & logistics | 2018 |
| Marekdevelopment Ltd | Information & communication | 2025 |
| Margaret Reid Properties Limited | Real estate | 1997 |
| Margaret-Rose Properties Maintenance Ltd | Real estate | 2020 |
| Margate Limited | Professional & scientific | 2015 |
| Margina Trading Ltd | Other services | 2019 |
| Margo Dirckx Ltd | Health & social care | 2022 |
| Margos Driver Ltd | Transport & logistics | 2014 |
| Marha Ltd | Hospitality | 2018 |
| Marhaba Money Ltd | Financial services | 2026 |
| MARHABA-1 Limited | Wholesale & retail | 2021 |
| Maria Ahmed 234 Limited | Professional & scientific | 2025 |
| Maria Community Ltd | Education | 2025 |
| Maria Jacob Ltd | Professional & scientific | 2022 |
| Maria Mallaband (6) Limited | Health & social care | 2010 |
| Maria Mallaband 11 Limited | Health & social care | 2011 |
| Maria Mallaband 12 Limited | Health & social care | 2013 |
| Maria Mallaband 13 Limited | Extraterritorial | 2013 |
| Maria Mallaband 14 Limited | Health & social care | 2013 |
| Maria Mallaband 15 Limited | Health & social care | 2013 |
| Maria Mallaband 16 Limited | Health & social care | 2014 |
| Maria Mallaband 17 Limited | Health & social care | 2014 |
| Maria Mallaband 7 Limited | Health & social care | 2010 |
| Maria Mallaband 9 Limited | Extraterritorial | 2011 |
| Maria Mallaband Care Group Limited | Construction | 1995 |
| Maria Mallaband Care Homes (2) Limited | Health & social care | 2006 |
| Maria Mallaband Care Homes Limited | Health & social care | 1995 |
| Maria Mallaband Limited | Health & social care | 1987 |
| Maria Mallaband Properties (4) Limited | Health & social care | 2008 |
| Maria Mallaband Properties (5) Limited | Health & social care | 2009 |
| Maria Nuneza Ltd | Health & social care | 2015 |
| Marian Acatrinei Limited | Transport & logistics | 2025 |
| Marian Delivery Ltd | Transport & logistics | 2025 |
| Marianevelyn Ltd | Transport & logistics | 2018 |
| Mariano Marino Limited | Information & communication | 2013 |
| Marici Health Ltd | Health & social care | 2021 |
| Marie Brown Aesthetics Ltd | Other services | 2021 |
| Marie Brown Aesthetics Training Academy Ltd | Education | 2021 |
| Marie Cowling Limited | Information & communication | 2017 |
| Marie Myers Photography Ltd | Professional & scientific | 2023 |