| MC Utility Limited | Construction | 2019 |
| MC336 Limited | Real estate | 2004 |
| MC337 Limited | Real estate | 2004 |
| MC4 Properties Ltd | Real estate | 2025 |
| Mcalpine Grant Ilco Limited | Construction | 1998 |
| MCB Assets Ltd | Financial services | 2021 |
| MCB Group Holdings Ltd | Financial services | 2023 |
| Mcbill Illustration Ltd | Information & communication | 2013 |
| Mccabemedicolegal Limited | Financial services | 2011 |
| Mccadam Ltd | Construction | 2020 |
| Mccauley Build Ltd | Construction | 2025 |
| Mccauley Construction Limited | Construction | 2016 |
| Mccourt Developments Limited | Real estate | 2021 |
| Mccubbin Properties Ltd | Real estate | 2025 |
| MCD Equity Ltd | Real estate | 2024 |
| Mcdonagh PUB Group Ltd | Hospitality | 2025 |
| Mcet Consulting Ltd | Information & communication | 2021 |
| Mcevoy Consulting Limited | Professional & scientific | 2013 |
| Mcgann Medical Limited | Health & social care | 2011 |
| Mcgee Scaffolding Contractors Ltd | Construction | 2007 |
| Mcgonnell & Gillatt Equine Veterinary Practice Limited | Administrative & support | 2005 |
| Mcguire Plumbing & Heating Specialist Ltd | Construction | 2019 |
| Mcgvp | Professional & scientific | 2017 |
| MCH Connection Ltd | Real estate | 2025 |
| MCH Hawthorn Ltd | Extraterritorial | 2024 |
| MCH Staverton Ltd | Real estate | 2024 |
| MCH Transfer Ltd | Real estate | 2024 |
| MCH Woodlands Ltd | Real estate | 2024 |
| Mchuk Ltd | Transport & logistics | 2024 |
| Mckelvey Properties Ltd | Real estate | 2025 |
| Mckeown Investments Limited | Financial services | 2023 |
| Mckeown Lettings Ltd | Real estate | 2017 |
| Mcloughlin Planning Ltd | Professional & scientific | 2009 |
| Mcneile Bloodstock Ltd | Agriculture & fishing | 2026 |
| Mcphee Engineering & Technology Services Limited | Administrative & support | 2016 |
| Mcpherson Shooting Ltd | Arts & recreation | 2016 |
| Mcwilliam International Finance Limited | Financial services | 2004 |
| MD Builders Limited | Construction | 2018 |
| MDB 1 Limited | Professional & scientific | 2025 |
| MDB 2 Limited | Professional & scientific | 2025 |
| Mdesigns Associates Ltd | Professional & scientific | 2012 |
| MDN Construction (Cheltenham) Limited | Construction | 2005 |
| MDS Financial Services Ltd | Financial services | 2024 |
| ME and YOU Estate Agents Ltd | Real estate | 2015 |
| ME and YOU Sales Ltd | Real estate | 2021 |
| ME Estates Limited | Real estate | 2016 |
| ME Time Solutions Limited | Health & social care | 2020 |
| Mead Park Management Limited | Real estate | 2002 |
| Meadent Limited | Health & social care | 2019 |
| Meades & Wiggan Childcare Ltd | Education | 2010 |
| Meadgate Pharma Solutions Limited | Other services | 2018 |
| Meadow Cafe Limited | Hospitality | 2018 |
| Meadow Cafe Trading Limited | Hospitality | 2025 |
| Meadow Fields Marquees Limited | Hospitality | 2006 |
| Meadowbrook Holdings Limited | Professional & scientific | 2004 |
| Meadowmews Management Company Limited | Households | 1998 |
| Meadows Day Nursery Limited | Education | 1998 |
| Meanings Matter Limited | Health & social care | 2017 |
| Measured Wealth Management Ltd | Financial services | 2025 |
| MEC Equity Ltd | Real estate | 2017 |
| Mechanical Asset Contractors Ltd | Construction | 2025 |
| Mechanical Simulations Limited | Professional & scientific | 2023 |
| Mechelec Bodies Ltd | Manufacturing | 2014 |
| Mecs Capital Management PTY Ltd | | 2021 |
| MED Hold Ltd | Financial services | 2019 |
| MED Style Limited | Hospitality | 2018 |
| Medi-Ceuticals Limited | Administrative & support | 2014 |
| Media Storm Ltd | Professional & scientific | 2019 |
| Mediareach Limited | Administrative & support | 2003 |
| Medica Instrumentae Limited | Professional & scientific | 2017 |
| Medical Aesthetics by ZIA Ltd | Health & social care | 2026 |
| Medical Aesthetics London Limited | Health & social care | 2018 |
| Medical Secretarial Solutions Limited | Administrative & support | 2024 |
| Medics and Surgeons Limited | Health & social care | 2018 |
| Medilink Communications Ltd. | Professional & scientific | 2008 |
| Medilink Pharma Limited | Administrative & support | 2024 |
| Medimex Ltd | Real estate | 2017 |
| Medina Trading Ltd | Wholesale & retail | 2017 |
| Medlar Consultants Limited | Administrative & support | 2020 |
| Medsoner Ltd | Professional & scientific | 2019 |
| Medway Flexpower Ltd | Energy | 2021 |
| Meelboom Consulting Ltd | Information & communication | 2025 |
| Meep Limited | Financial services | 2025 |
| Meeru Property Services Limited | Real estate | 2012 |
| Meetfit Ltd | Arts & recreation | 2022 |
| Megalodon Electrical Ltd | Construction | 2022 |
| Mego Properties Limited | Real estate | 2019 |
| Mehendale Orthopaedics Limited | Health & social care | 2020 |
| Meher Catering Ltd | Hospitality | 2019 |
| Meister Masonry Limited | Construction | 2005 |
| Mejconsult Ltd | Professional & scientific | 2026 |
| Mejventures Ltd | Arts & recreation | 2026 |
| Mekkara Architectural Consultants Limited | Real estate | 2016 |
| Meko Trade Ltd | Construction | 2020 |
| Mekong Property Limited | Real estate | 2019 |
| Mekong Solutions Limited | Information & communication | 2004 |
| Meleam Ltd | Real estate | 2024 |
| Mellington Management Limited | Households | 1981 |
| Mello Drinks Ltd | Manufacturing | 2011 |
| Mellor Enterprises Ltd | Information & communication | 2011 |