| Martakosa Ltd | Real estate | 2022 |
| Master Home Chef Limited | Hospitality | 2021 |
| Master POL Plus Ltd | Construction | 2021 |
| Master Roofers UK Limited | Education | 2020 |
| Masu Industrial Services Ltd | Professional & scientific | 2020 |
| Match Lettings Ltd | Real estate | 2020 |
| Mawutornam Ltd | Health & social care | 2026 |
| MAX Drone Pro Ltd | Other services | 2020 |
| Maximum Impact Accountants Ltd | Professional & scientific | 2019 |
| Maxwell Tech Solutions Ltd | Wholesale & retail | 2021 |
| MB Hydrographic Limited | Professional & scientific | 2006 |
| Mbrook Holdings Ltd | Professional & scientific | 2022 |
| Mbrook Investments Ltd | Professional & scientific | 2022 |
| MC Leak Detection Limited | Construction | 2024 |
| Mcaj Solutions Limited | Professional & scientific | 2014 |
| Mccormack Fabrications Limited | Manufacturing | 2014 |
| Mcg&Co Ltd | Professional & scientific | 2023 |
| Mcgibbon Logistics Ltd | Transport & logistics | 2025 |
| MCL Homes Limited | Real estate | 2012 |
| Mclarney PUB and Bar Services Ltd | Hospitality | 2024 |
| MCM Fleet Services Ltd | Wholesale & retail | 2023 |
| Mcnamaras Sports Bar & Academy Ltd | Hospitality | 2026 |
| MDB GAS Ltd | Energy | 2018 |
| MDS Haulage Ltd | Transport & logistics | 2022 |
| Meac Limited | Construction | 2026 |
| Meadowgate Farm Management Company Limited | Extraterritorial | 2000 |
| Mechanical and Electrical Associates (UK) Limited | Professional & scientific | 1988 |
| Medallion Properties Ltd | Real estate | 2019 |
| Median Consulting Ltd | Professional & scientific | 2022 |
| Medical Beauty Enhancement Ltd | Health & social care | 2013 |
| Meerock Ltd | Wholesale & retail | 2025 |
| Meerum Limited | Wholesale & retail | 2024 |
| Mega-Watt Electronics LLP | | 2011 |
| Meller Print & Design Limited | Administrative & support | 2016 |
| Mellow’S Wellness Creations C.I.C. | Education | 2025 |
| Memo-Ziol Ltd | Transport & logistics | 2024 |
| Mercer Law Ltd | Professional & scientific | 2013 |
| Meridian 1968 Limited | Extraterritorial | 2014 |
| Meridian Electrical Solutions Ltd | Construction | 2024 |
| Mersey Bridge View Limited | Hospitality | 2013 |
| Mersey Bunkering Limited | Wholesale & retail | 1975 |
| Mersey Gateway Crossings Board Ltd | Professional & scientific | 2013 |
| Mersey Gateway Environmental Trust | Professional & scientific | 2010 |
| Mersey MOT Ltd | Wholesale & retail | 2024 |
| Mersey Valley Land Recovery Limited | Water & waste | 2013 |
| Merseyflow Limited | Professional & scientific | 2017 |
| Merseylink (Finance) Limited | Construction | 2013 |
| Merseylink (Holdings) Limited | Construction | 2013 |
| Merseylink (Issuer) PLC | Financial services | 2014 |
| Merseylink Limited | Construction | 2013 |
| Merseyside Industrial Services Limited | Manufacturing | 2011 |
| Merseyview Garage Ltd | Wholesale & retail | 2023 |
| Merseyview Garage Rent Ltd | Real estate | 2023 |
| Metrohm UK Limited | Wholesale & retail | 1994 |
| Mexichem Fluor EU B.V. | | 2017 |
| Mexichem UK Limited | Manufacturing | 2009 |
| MF Express Laundry Ltd | Other services | 2013 |
| Mfl-Com Limited | Wholesale & retail | 2021 |
| MG GAS Ltd | Construction | 2023 |
| Middlebrook Holdings Limited | Financial services | 2021 |
| Middlebrook Transport Limited | Transport & logistics | 1984 |
| Midway Homes Ltd | Real estate | 2025 |
| Mihai Petrisor Limited | Transport & logistics | 2016 |
| Mike Cowley Ltd | Information & communication | 2003 |
| Mikelyte Ltd | Hospitality | 2023 |
| Milkwood Marketing Ltd. | Professional & scientific | 2012 |
| Millb 2018 Ltd | Financial services | 2018 |
| Millbank Holdings Limited | Professional & scientific | 1995 |
| Millbank Rail Limited | Administrative & support | 2017 |
| Millbank Resource Management Limited | Administrative & support | 1985 |
| Mimo (NW) Ltd | Wholesale & retail | 2025 |
| Mind & Beyond Healthcare Ltd | Public administration | 2024 |
| Mindset Strength Fitness Ltd | Arts & recreation | 2025 |
| Mini Party Hire Ltd | Administrative & support | 2026 |
| Miranda’S Interiors Ltd | Wholesale & retail | 2024 |
| Mirno Ltd | Information & communication | 2026 |
| Mirror Image Community Training Ltd | Education | 2020 |
| Mirror Image Hairdressers (Runcorn) Limited | Other services | 2002 |
| Mislingford Ltd | Transport & logistics | 2015 |
| MIT Beauty & Spa Ltd | Other services | 2025 |
| MJ Beauty Room Ltd | Wholesale & retail | 2014 |
| MJM Property Holdings Limited | Real estate | 2003 |
| MJO Sons Ltd | Construction | 2013 |
| MK Sports Academy Ltd | Education | 2026 |
| Mkav Consultancy Ltd | Financial services | 2012 |
| ML Procurement Services Ltd | Professional & scientific | 2010 |
| MLB Solutions Ltd | Transport & logistics | 2016 |
| MLR Networks (Holdings) Limited | Information & communication | 2009 |
| MLR Networks Ltd | Information & communication | 1988 |
| MMG Logistics Ltd | Transport & logistics | 2023 |
| MMJ Services Ltd | Transport & logistics | 2009 |
| Mobathrooms Ltd | Construction | 2026 |
| Modol Transport Ltd | Transport & logistics | 2025 |
| Modular Refrigeration Systems Ltd | Construction | 2001 |
| Molster Ltd | Real estate | 2026 |
| Moodboard Stock Photography Ltd | Professional & scientific | 2005 |
| Moore Business Management Limited | Administrative & support | 2015 |
| Moore Homes U.K. Ltd | Real estate | 2017 |
| More Glass and Joinery Limited | Construction | 2007 |
| Motorrad Limited | Professional & scientific | 2015 |