| MDP Express Transport Ltd | Transport & logistics | 2019 |
| MDR Technical Services Limited | Administrative & support | 2025 |
| MDS CEM Holdings Limited | Information & communication | 2011 |
| MDS Global Ltd | Information & communication | 1988 |
| MDS Group Autos Limited | Wholesale & retail | 2025 |
| MDS Group Cheshire Limited | Construction | 2014 |
| MDT Rentals Ltd | Real estate | 2021 |
| Mduk Transport Services Limited | Transport & logistics | 2022 |
| MDW Consultancy Solutions Ltd | Professional & scientific | 2020 |
| MEA Trans Ltd | Transport & logistics | 2025 |
| Meacher Enterprises Ltd | Administrative & support | 2021 |
| Meadow Cross Construction Limited | Construction | 2018 |
| Meadow View Consultancy Ltd | Professional & scientific | 2020 |
| Meadowbrook Woodland Trust Ltd | Other services | 2014 |
| Meadowcroft Projects Ltd | Construction | 2023 |
| Meadows Design Limited | Administrative & support | 2026 |
| Meadowside Studio Limited | Professional & scientific | 2021 |
| Meadway Associates Limited | Professional & scientific | 2017 |
| Meakin&Co Ltd | Wholesale & retail | 2025 |
| Mean Studio Limited | Information & communication | 2018 |
| Meass Group Ltd | Construction | 2024 |
| MEB Electrical Services Ltd | Professional & scientific | 2023 |
| MEC IT Consulting Limited | Information & communication | 2016 |
| Mechanical Engineering & Aviation Solutions Ltd | Administrative & support | 2025 |
| Mecre Thomson Ltd | Administrative & support | 2026 |
| Mecrews Healthcare Ltd | Health & social care | 2021 |
| Mecx Limited | Professional & scientific | 2022 |
| Medd Ltd | Administrative & support | 2007 |
| Meddiary Ltd | Information & communication | 2017 |
| Medflex Locum Ltd | Health & social care | 2024 |
| Media and Digital Ltd | Other services | 2000 |
| Media Technology Group Ltd | Professional & scientific | 2018 |
| Mediation and Drafting Experts Limited | Administrative & support | 2025 |
| Medical and Medico Legal Secretarial Services Limited | Administrative & support | 2015 |
| Medical Assessment Reporting Services Limited | Administrative & support | 2002 |
| Medical Research Services Ltd | Professional & scientific | 2026 |
| Medical RT Limited | Administrative & support | 2025 |
| Medication Management Solutions Ltd | Information & communication | 2004 |
| Medico (Warrington) Ltd | Health & social care | 2021 |
| Mediscans Diagnostics Limited | Health & social care | 2025 |
| Medispace Diagnostics Ltd | Health & social care | 2020 |
| Mediterranean Yacht Charters Limited | Arts & recreation | 2019 |
| Medley Music for Schools Ltd | Education | 2017 |
| Medline Industries Limited | Administrative & support | 1996 |
| Medline Operations Ltd | Wholesale & retail | 2017 |
| Medline Stellar UK Limited | Financial services | 2011 |
| Medprotect Limited | Health & social care | 2003 |
| Medway Consultancy Limited | Professional & scientific | 2024 |
| Meesh Information and Communications Knowledge Limited | Information & communication | 2014 |
| Meet the Baby Ltd | Other services | 2019 |
| Mega Pink Horse Ltd | Agriculture & fishing | 2012 |
| Megan Jayne Hair Studio Ltd | Other services | 2023 |
| Mehdi Consulting Co. Ltd | Mining & quarrying | 2019 |
| Mehta Technology Limited | Information & communication | 2018 |
| MEI Investment Holdings Ltd | Financial services | 2021 |
| Meica Construction Systems Limited | Administrative & support | 2010 |
| Meikle Wartle Engineering Limited | Professional & scientific | 2019 |
| Meistech Ltd | Wholesale & retail | 2017 |
| Meiwear Limited | Wholesale & retail | 2025 |
| MEJ IT Consultancy Limited | Administrative & support | 2014 |
| Mejah Limited | Wholesale & retail | 2021 |
| MEL Capelli Ltd | Other services | 2023 |
| Melanie Berry Ltd | Administrative & support | 2023 |
| Melapis Consulting Limited | Professional & scientific | 2023 |
| Melba Petcare Ltd | Professional & scientific | 2020 |
| Melbourne Care Limited | Health & social care | 2015 |
| Meleo Group Ltd | Professional & scientific | 2023 |
| Meliant Ltd | Administrative & support | 2023 |
| Meliora Consulting Limited | Administrative & support | 2011 |
| Meliora Software Ltd | Information & communication | 2018 |
| Melissa Wood Ltd | Professional & scientific | 2015 |
| Melling Lane Developments Limited | Construction | 2021 |
| Mellon Motor Limited | Wholesale & retail | 2023 |
| Mellor & Smith Design Ltd | Professional & scientific | 2009 |
| Mellow Medical PVT Ltd | Health & social care | 2024 |
| Mellowe Landscapes Limited | Administrative & support | 2012 |
| Mellymoo Consulting Ltd | Administrative & support | 2026 |
| Melody Residential Ltd | Real estate | 2020 |
| Melomania Limited | Administrative & support | 2015 |
| Melso Print Company Limited | Manufacturing | 1997 |
| Melstock Inspections Limited | Administrative & support | 2024 |
| Memco Collaborations Ltd | Professional & scientific | 2021 |
| Memerootfotwo Limited | Information & communication | 2017 |
| Memory Lane Holidays & Travel Ltd | Transport & logistics | 2020 |
| Mendez Prestige Ltd | Wholesale & retail | 2020 |
| Menendez Software Limited | Information & communication | 2017 |
| Menic Designs Ltd | Arts & recreation | 2025 |
| Menono Ltd | Information & communication | 2018 |
| Menopause and ME Limited | Health & social care | 2024 |
| Mentalia Locums Ltd | Administrative & support | 2025 |
| Mentalitee CIC | Health & social care | 2026 |
| Mentally Limited | Wholesale & retail | 2002 |
| Mentor Partners Ltd | Education | 2024 |
| Menzies Consultants Ltd. | Administrative & support | 2021 |
| Meraki Medical Aesthetics Clinic Ltd | Other services | 2021 |
| Meraki Woodcraft Ltd | Manufacturing | 2020 |
| Meramo Ltd | Information & communication | 2013 |
| Mercho Ltd | Professional & scientific | 2013 |
| Mercury Project Engineering Limited | Professional & scientific | 2008 |
| Mercury Storm Ltd | Professional & scientific | 2016 |