| Manan Trading Ltd | Transport & logistics | 2024 |
| Mani Trading Ltd | Transport & logistics | 2021 |
| Mania UK Trading Ltd | Construction | 2019 |
| Mano Rajendran Ltd | Real estate | 2025 |
| Mansoor Holds Ltd | Financial services | 2024 |
| Mansoor Property INV Ltd | Real estate | 2024 |
| Mansoor Traders Ltd | Transport & logistics | 2021 |
| Manzal Property Group Ltd | Households | 2020 |
| MAQ Constructions Ltd | Construction | 2021 |
| MAQ Consulting Ltd | Information & communication | 2012 |
| MAQ London Ltd | Construction | 2017 |
| MAR Builders London Limited | Construction | 2016 |
| MAR Medical Ltd | Health & social care | 2020 |
| MAR Trading London Ltd | Transport & logistics | 2020 |
| Mara Management Properties Ltd | Real estate | 2026 |
| Marac Trans Ltd | Transport & logistics | 2017 |
| Marconi London Ltd | Construction | 2016 |
| Marcwilliambannerman Ltd | Extraterritorial | 2025 |
| Mardar Management Singing Waiters Limited | Arts & recreation | 2000 |
| Marfat Trading Company Ltd. | Wholesale & retail | 2024 |
| Marginmotors Ltd | Wholesale & retail | 2026 |
| Marjan Trading Ltd | Wholesale & retail | 2026 |
| Mark William Bannerman Limited | Extraterritorial | 2024 |
| Market Dada Ltd | Wholesale & retail | 2025 |
| Marketing Commando Ltd | Information & communication | 2012 |
| Marlay Digital Limited | Information & communication | 2013 |
| Marlins Developments Ltd | Real estate | 2015 |
| Marlins Enterprises Limited | Administrative & support | 2015 |
| Marlins Holdings Limited | Real estate | 2017 |
| Marlins West Limited | Real estate | 2017 |
| Marni Matharu Limited | Real estate | 2025 |
| Marnz Holds Ltd | Financial services | 2024 |
| Marnz Property Investment Ltd | Real estate | 2024 |
| Maroon Solis CIC | Health & social care | 2021 |
| Maroush Elite Limited | Hospitality | 2023 |
| Marry Sunshining Limited | Construction | 2024 |
| Marsal ALY & Heathers Ltd | Professional & scientific | 2025 |
| Marta Canga Limited | Professional & scientific | 2022 |
| Martin Cars Ltd | Wholesale & retail | 2016 |
| Martini Contractors Limited | Construction | 2010 |
| Mary Louise Gill Limited | Extraterritorial | 2024 |
| Maryam Estates and Investment Ltd | Real estate | 2020 |
| MAS Holds Ltd | Financial services | 2026 |
| Masa Enterprise Limited | Health & social care | 2013 |
| Masa Holds Ltd | Financial services | 2024 |
| Masa Housing LLP | | 2017 |
| Maskd Property Ltd | Real estate | 2020 |
| Masood Dadras Ltd | Real estate | 2020 |
| Maspack Trading Ltd | Wholesale & retail | 2025 |
| Masras Medical Services Limited | Health & social care | 2018 |
| Masroor Healthcare Foundation | Other services | 2023 |
| Master Bricks Limited | Wholesale & retail | 2025 |
| Matco Civils and Utilities Ltd | Construction | 2026 |
| Matco Real Estate Ltd | Real estate | 2025 |
| Matco Structures & Consulting Ltd | Professional & scientific | 2026 |
| Maticsmart Ltd | Wholesale & retail | 2026 |
| Matt Brash Builders Ltd | Construction | 2023 |
| Matulo Holding 25 Ltd | Financial services | 2021 |
| Mauj-Uk Limited | Health & social care | 2026 |
| Mavesevans Ltd | Wholesale & retail | 2017 |
| Mavigo Groups Limited | Wholesale & retail | 2025 |
| MAX Holds Ltd | Financial services | 2024 |
| MAX London Limited | Health & social care | 2015 |
| MAX Management Solutions Ltd | Real estate | 2024 |
| MAX Property INV Ltd | Real estate | 2024 |
| MAX Space Ltd | Construction | 2016 |
| Maxland Management Limited | Administrative & support | 2001 |
| Maxx Motors Ltd | Wholesale & retail | 2021 |
| MAY Project Gardens CIC | Education | 2015 |
| Maycross Admin Ltd | Real estate | 2024 |
| Maycross Properties Limited | Real estate | 2003 |
| Mayfield Housing Ltd | Real estate | 2022 |
| Mazovia Projects Ltd | Construction | 2026 |
| MB London Limited | Financial services | 2022 |
| MBF Publishing Ltd | Education | 2021 |
| MBI Curtain Wall Solutions Ltd | Construction | 2004 |
| MBT Properties Ltd | Real estate | 2018 |
| MC Vascular Ltd | Health & social care | 2021 |
| Mcbigc Limited | Professional & scientific | 2021 |
| Mclansey Consulting Limited | Information & communication | 2013 |
| MCM Installations Ltd | Construction | 2019 |
| Mcompany Consulting Ltd | Wholesale & retail | 2022 |
| MD Rarawa UK Limited | Professional & scientific | 2024 |
| MD Super Safety Ltd | Professional & scientific | 2023 |
| MD Trading London Ltd | Transport & logistics | 2024 |
| MDK Plumbing Limited | Construction | 2023 |
| MDN Trading Ltd | Transport & logistics | 2019 |
| Mdyers Limited | Construction | 2015 |
| Meals for Keyworkers Ltd | Hospitality | 2020 |
| Meat&Meat Traders UK Ltd | Wholesale & retail | 2025 |
| Meda Trading Ltd | Transport & logistics | 2020 |
| Medclix Holds Ltd | Financial services | 2025 |
| Medclix Limited | Wholesale & retail | 2013 |
| Medecure Ltd | Manufacturing | 2024 |
| Medi Consultants Limited | Information & communication | 2011 |
| Medi Gazette Ltd | Manufacturing | 2018 |
| Media Art Ltd | Information & communication | 2001 |
| Media Finance Consulting Ltd | Information & communication | 2024 |
| Medic Martin Ltd | Health & social care | 2023 |
| Medicawise Ltd | Health & social care | 2025 |