| MSR Research Ltd | Health & social care | 2026 |
| Msrj Properties Ltd | Construction | 2023 |
| MSS Capital Limited | Financial services | 2000 |
| Mssa Health Ltd | Public administration | 2021 |
| Mssa Investments Ltd | Real estate | 2020 |
| MST Service Ltd | Wholesale & retail | 2019 |
| Msv.Sm Ltd | Real estate | 2023 |
| MSW Law Ltd | Professional & scientific | 2025 |
| MT Financial Planning Limited | Administrative & support | 2020 |
| MT Management Services Ltd | Professional & scientific | 2023 |
| MTA Aurelion Ltd | Professional & scientific | 2021 |
| MTA Consultants Ltd | Financial services | 2018 |
| MTC Consultancy Services Limited | Professional & scientific | 2023 |
| MTD Digital Solutions Ltd | Information & communication | 2025 |
| MTD Harrow Bookkeepers Ltd | Professional & scientific | 2018 |
| Mtdh Consulting Ltd | Professional & scientific | 2015 |
| MTK Life Ltd | Wholesale & retail | 2018 |
| MTK Property Investments Limited | Real estate | 2022 |
| MU Property Group Ltd | Real estate | 2025 |
| Mualifahh Limited | Real estate | 2016 |
| Muanda Consulting Limited | Professional & scientific | 2018 |
| Mubarak Property Development Limited | Real estate | 2022 |
| Muchachos Kingsbury Limited | Other services | 2016 |
| Muchnote Limited | Professional & scientific | 2003 |
| Mudan AD Ltd | Professional & scientific | 2021 |
| Mudassir ALI Group Limited | Wholesale & retail | 2016 |
| Muddy Brand Ltd | Wholesale & retail | 2025 |
| MUG Productions Ltd | Information & communication | 2021 |
| Mugen (GB) Limited | Hospitality | 2014 |
| Mugen Farringdon Limited | Real estate | 2014 |
| Mughal Brothers Global Ltd | Wholesale & retail | 2025 |
| Muhammad Ishaq Commando & Co. Global Ltd | Construction | 2025 |
| Muji Consulting Ltd | Information & communication | 2019 |
| Mukherjee Family Properties Limited | Real estate | 2019 |
| Mukt Muni Ltd | Hospitality | 2021 |
| Mukti Properties Ltd | Real estate | 2021 |
| Mulberry Business Group Ltd | Health & social care | 2016 |
| Mulberry Food Ltd | Wholesale & retail | 2024 |
| Mulberry Land and Development Limited | Professional & scientific | 2018 |
| Mulberry Whole Foods Plus Ltd | Wholesale & retail | 2018 |
| Mule-It Ltd | Other services | 2026 |
| Mullai Food Limited | Wholesale & retail | 2019 |
| Mullarkey Contractors Ltd | Construction | 2015 |
| Mullarkey Developments Ltd | Construction | 2023 |
| Mullarkey Group Limited | Financial services | 2023 |
| Mullarkey Holdings Limited | Real estate | 2017 |
| Mullarkey Investments Ltd | Real estate | 2015 |
| Mulley Management Ltd | Professional & scientific | 2025 |
| Mullion Cove Ltd | Real estate | 2019 |
| Mully Consultancy Limited | Extraterritorial | 2019 |
| Multani's Solutions Ltd | Professional & scientific | 2024 |
| Multi Group Construction Limited | Construction | 2019 |
| Multi Hospitality Supplies UK Ltd | Wholesale & retail | 2022 |
| Multi House Ltd | Real estate | 2024 |
| Multi Industrial Estate Limited | Real estate | 2015 |
| Multi Trade Links (UK) Ltd | Wholesale & retail | 2008 |
| Multichannel Marketing Ltd | Professional & scientific | 2011 |
| Multicount Limited | Financial services | 1988 |
| Multie Choice Ltd | Other services | 2015 |
| Multifab-Tech Ltd. | Administrative & support | 2017 |
| Multiped Ltd | Administrative & support | 2019 |
| Multipeduk Limited | Wholesale & retail | 2019 |
| Multisteel Doors Limited | Manufacturing | 2004 |
| Multiuse Property Services Limited | Real estate | 2018 |
| Mulvir & Sons Limited | Wholesale & retail | 1977 |
| Mulvir Investments Limited | Real estate | 2021 |
| Mumbai 3D Conversion Ltd | Information & communication | 2012 |
| Mumbai Junction Ltd | Hospitality | 2026 |
| Mumbai Mirchi Ltd | Hospitality | 2025 |
| Mumbaikar Vadapav Limited | Hospitality | 2021 |
| Mumbaiwala Ltd | Hospitality | 2023 |
| Mumbaiwala Restaurant Ltd | Hospitality | 2025 |
| Muna Pharma Ltd | Health & social care | 2026 |
| Munch "N" Crunch Limited | Hospitality | 2012 |
| Munch Mates UK Ltd | Hospitality | 2025 |
| Mundari LLP | | 2020 |
| Mundhari Limited | Wholesale & retail | 2019 |
| Mundo Cognito Ltd | Professional & scientific | 2018 |
| Munizah UK Limited | Wholesale & retail | 2024 |
| Munster Surveying Limited | Professional & scientific | 2010 |
| Munteanu Services Ltd | Construction | 2020 |
| Murad Hire Ltd | Other services | 2017 |
| Muragen Limited | Hospitality | 2017 |
| Muralii Usha Property Ltd | Real estate | 2018 |
| Muraru Trans Ltd | Transport & logistics | 2018 |
| Muriwai Consultants Limited | Professional & scientific | 2024 |
| Murlidhar Business Limited | Wholesale & retail | 2025 |
| Murphy Logic Limited | Information & communication | 2000 |
| Murphys Contractors Limited | Administrative & support | 2010 |
| Murphys Roofing and Building Ltd | Construction | 2021 |
| Murray & Flynn Decorators Limited | Construction | 2021 |
| Murray Chauffeur Services Limited | Administrative & support | 2010 |
| Murray-Johnson Consultants Limited | Professional & scientific | 2012 |
| Murray-West Media Limited | Information & communication | 2013 |
| Murugathasan Limited | Real estate | 2025 |
| Murugesh & Co Ltd | Professional & scientific | 2025 |
| Muruguna Investments Ltd | Real estate | 2023 |
| Musa Academy Limited | Education | 2018 |
| Musam Limited | Professional & scientific | 2023 |
| Muse Paper Limited | Information & communication | 2020 |