| Mayakka Ltd | Administrative & support | 2024 |
| Mayannan Consultancy Limited | Professional & scientific | 2015 |
| Mayannan Portfolios Limited | Real estate | 2019 |
| Maybank Lodge Management Company Limited | Households | 2003 |
| Maybrook House (Caterham) Management Company Ltd | Households | 2020 |
| Maybury Sports Limited | Wholesale & retail | 1986 |
| Mayday LDN Properties Ltd | Real estate | 2025 |
| Mayday Travel Limited | Transport & logistics | 2004 |
| Mayfair Cobblers Limited | Other services | 2015 |
| Mayfair Housing & Commercial Concerns Limited | Real estate | 2008 |
| Mayfair Housing & Commercial Investments Ltd. | Construction | 1949 |
| Mayfair Prestige Motors Ltd | Wholesale & retail | 2020 |
| Mayfield Court (Bromley) Limited | Households | 2002 |
| Mayfield Court (Bromley) Management Company Limited | Households | 1998 |
| Mayfield Court Estate Management Company Limited | Households | 2008 |
| Mayfield Mansions Freehold Limited | Households | 2000 |
| Mayfield Sussex Beef Producers Limited | Agriculture & fishing | 2000 |
| Mayfields Albert Road Management Limited | Households | 1987 |
| Mayflower House Management Company Limited | Households | 2013 |
| Mayford Construction Ltd | Construction | 2015 |
| Mayite Ltd | Information & communication | 2020 |
| Mayscope Limited | Extraterritorial | 2003 |
| Mayupp Limited | Wholesale & retail | 2024 |
| MAZ Car Hire Limited | Administrative & support | 2013 |
| Maze’S Cocktails Limited | Hospitality | 2025 |
| Mazha Ltd | Wholesale & retail | 2025 |
| Mazrreku Construction Ltd | Construction | 2015 |
| Mazumder TEC Inc Ltd | Information & communication | 2025 |
| Mazzard (South West) Limited | Construction | 2004 |
| MB Ductwork Limited | Construction | 2015 |
| MB Facilities Limited | Construction | 2017 |
| MB Health Limited | Health & social care | 2014 |
| MB Hillingdon Limited | Construction | 2015 |
| Mbalive Ltd | Professional & scientific | 2025 |
| Mbembi Ltd | Wholesale & retail | 2024 |
| Mbkcare Ltd | Public administration | 2024 |
| MBM Bathrooms Ltd | Construction | 2020 |
| MBO Resources UK Ltd | Professional & scientific | 2015 |
| Mboho Akwa Ibom State (UK & Ireland) Association Ltd | Administrative & support | 2003 |
| Mbw.O Ltd | Financial services | 2014 |
| MBZ Services Ltd | Transport & logistics | 2023 |
| MC Autos South Limited | Wholesale & retail | 2025 |
| MC Distributors UK Ltd | Wholesale & retail | 2020 |
| MC Hall Landscapes Ltd | Administrative & support | 2010 |
| MC Lift Installation Ltd | Manufacturing | 2026 |
| MC Solutions London Ltd | Construction | 2024 |
| MC SPV One Ltd | Real estate | 2021 |
| MC& Maintenance Ltd Ltd | Administrative & support | 2019 |
| Mc.Angel Ltd | Wholesale & retail | 2017 |
| MCA Plumbing Ltd | Construction | 2023 |
| Mcara Limited | Wholesale & retail | 2003 |
| MCB Butchers Ltd | Hospitality | 2017 |
| MCB Butchery Ltd | Hospitality | 2025 |
| Mccarthy Cars (UK) Limited | Wholesale & retail | 1988 |
| Mccobby Ltd | Wholesale & retail | 2024 |
| Mcdonough Clinical Research Limited | Professional & scientific | 2006 |
| Mcdrake Limited | Information & communication | 2020 |
| MCG MPF Enterprise Ltd | Wholesale & retail | 2025 |
| Mcguirk Capital Limited | Real estate | 2026 |
| Mckat Magic Masala PVT Ltd | Hospitality | 2023 |
| Mckenzie Dinnall Ltd | Real estate | 2025 |
| Mckenzies Inc Ltd | Financial services | 2025 |
| Mckoy Holdings Ltd | Real estate | 2024 |
| Mclaren (Finance 1) Limited | Administrative & support | 2016 |
| Mcleod & Gayle Holdings Ltd | Real estate | 2026 |
| Mcloughlin Maisons Limited | Real estate | 2019 |
| Mcmm PR Limited | Professional & scientific | 2021 |
| MCQ Entertainments Limited | Wholesale & retail | 1975 |
| Mcrae Residential Care Services Limited | Health & social care | 1998 |
| MCS Express Ltd | Transport & logistics | 2024 |
| Mcyp Limited | Administrative & support | 2020 |
| MD Cafe Ltd | Hospitality | 2026 |
| MD Investments Limited | Real estate | 1999 |
| MD Sweets Limited | Wholesale & retail | 2021 |
| MD Walker Property Ltd | Administrative & support | 2023 |
| MDA Healthcare Limited | Administrative & support | 2017 |
| MDA Jones Limited | Professional & scientific | 2012 |
| Mdcec Ltd | Administrative & support | 2017 |
| Mdgb Holdco Limited | Financial services | 2024 |
| MDH Accountants Limited | Extraterritorial | 2017 |
| MDH Audit Limited | Extraterritorial | 2012 |
| MDH Bookkeeping Limited | Extraterritorial | 2012 |
| MDH CC Accountants Ltd | Extraterritorial | 2012 |
| MDH Financial Partners Ltd. | Financial services | 2015 |
| MDH Limited | Financial services | 2010 |
| MDH Secretarial Limited | Extraterritorial | 2014 |
| MDH Small Business Limited | Professional & scientific | 2006 |
| MDH Tax Ltd | Extraterritorial | 2014 |
| MDI Electrical Limited | Construction | 2019 |
| MDK Electrical Services Ltd | Construction | 2021 |
| MDL Solicitors Ltd. | Professional & scientific | 2012 |
| Mdm-It Ltd. | Wholesale & retail | 2013 |
| Mdmk 2506 Ltd | Construction | 2022 |
| Mdosteo Ltd | Health & social care | 2022 |
| MDR Gems & Jewellery Limited | Wholesale & retail | 2017 |
| MDS Facilities Ltd | Administrative & support | 2026 |
| MDU Consulting Ltd | Administrative & support | 2022 |
| ME & My Sister Ltd | Real estate | 2018 |
| ME Taxi Services Ltd | Transport & logistics | 2026 |
| Mead Estates Investments Limited | Real estate | 2010 |