| Lyrus Life Sciences Limited | Professional & scientific | 2016 |
| LYV Transport Limited | Other services | 2016 |
| M & R Edwards Limited | Real estate | 2023 |
| M & S Reprographics Limited | Extraterritorial | 1993 |
| M a Abedian Ltd | Real estate | 2016 |
| M AAR Building Limited | Construction | 2018 |
| M Biring Ltd | Wholesale & retail | 2026 |
| M C and P C Investments Ltd | Real estate | 2022 |
| M Cannon Engineering Ltd | Professional & scientific | 2025 |
| M Eyecare Limited | Health & social care | 2025 |
| M Flynn Carpentry and Building Ltd | Construction | 2026 |
| M J Design & Building Ltd | Construction | 2016 |
| M King & Co Ltd | Professional & scientific | 2022 |
| M LIS Beauty Stylist Limited | Other services | 2017 |
| M Nambiar Limited | Professional & scientific | 2016 |
| M P Landscaping Ltd | Extraterritorial | 2022 |
| M R Scenic Design Ltd | Information & communication | 2016 |
| M S Gosal Builders Limited | Construction | 2008 |
| M Safi Ltd | Wholesale & retail | 2023 |
| M Trim Ltd | Manufacturing | 2020 |
| M Walsh Plant Hire Limited | Construction | 1987 |
| M&B Trade Group Ltd | Wholesale & retail | 2025 |
| M&C Imports Group Ltd | Wholesale & retail | 2024 |
| M&I Tiling Solution Ltd | Construction | 2023 |
| M&I Wholesalers Limited | Wholesale & retail | 2023 |
| M&M City Plumbing and Heating Limited | Construction | 2015 |
| M&M Construction (London) Ltd | Construction | 2017 |
| M&M Executives Ltd | Transport & logistics | 2023 |
| M&M Hair Studio 4 Limited | Other services | 2025 |
| M&M Property Lets Limited | Administrative & support | 2026 |
| M&M Property Partners Ltd | Real estate | 2025 |
| M&P Homes & Investments Ltd | Real estate | 2022 |
| M&S Fusion Ltd | Administrative & support | 2025 |
| M&S Patel Real Estate Limited | Real estate | 2018 |
| M&U Collection Ltd | Wholesale & retail | 2024 |
| M-Base Property Management Ltd | Households | 2019 |
| M. a. Productions Dumfries Ltd | Arts & recreation | 2011 |
| M.A Fashionz Ltd | Wholesale & retail | 2025 |
| M.A.Sempa Limited | Professional & scientific | 2007 |
| M.G.K. Consultancy Ltd | Professional & scientific | 2023 |
| M.J.M.Maintenance Ltd | Administrative & support | 2015 |
| M.L. Trading International Ltd | Wholesale & retail | 2026 |
| M.Ohm Ltd | Real estate | 2014 |
| M.S (London) Properties Ltd | Construction | 2013 |
| M.S.L Properties Without Limits Ltd | Real estate | 2024 |
| M1'S Kitchen Limited | Hospitality | 2024 |
| M13 Restoration Ltd | Construction | 2014 |
| M2 Computing Ltd | Information & communication | 1997 |
| M23 Projects Limited | Wholesale & retail | 2024 |
| M25 Copiers Limited | Wholesale & retail | 1999 |
| M3K Ltd | Extraterritorial | 2022 |
| M4 Group Limited | Construction | 2020 |
| M4SUNITED(THROUGH Sport) CIC | Other services | 2025 |
| MAA Cars Ltd | Wholesale & retail | 2019 |
| MAA Energy Ltd | Energy | 2025 |
| Maahi Properties Limited | Real estate | 2023 |
| Maav Ltd | Real estate | 2026 |
| Mabb Ltd | Information & communication | 2025 |
| Mace & Armaan Investments Ltd | Construction | 2020 |
| Macmillan House Management Limited | Households | 1993 |
| Macroy Property Limited | Real estate | 2021 |
| Macstore Ltd | Real estate | 2026 |
| Macys Group Limited | Construction | 2022 |
| MAD Label Ltd | Information & communication | 2022 |
| Madad Holding Limited | Real estate | 2021 |
| Madamm SI Ltd | Other services | 2022 |
| Madan Homes Ltd | Real estate | 2024 |
| Made by Masih Ltd | Professional & scientific | 2024 |
| Madhan Holding Group Ltd | Real estate | 2024 |
| Madinah & Shahzadi Ltd | Wholesale & retail | 2020 |
| Madison Property Maintenance Ltd | Construction | 2023 |
| Madjec Properties Ltd | Real estate | 2005 |
| Mads Products Ltd | Wholesale & retail | 2021 |
| Maenterprisess Ltd | Wholesale & retail | 2025 |
| Mafhh Tech Limited | Wholesale & retail | 2020 |
| MAG General Building Ltd | Construction | 2016 |
| Magdaviss Limited | Health & social care | 2013 |
| Magic Clean London Ltd | Administrative & support | 2024 |
| Magic FIX Enterprises Limited | Construction | 2022 |
| Magic Transport Ltd | Transport & logistics | 2019 |
| Magicmob Ltd | Professional & scientific | 2025 |
| Magics Ace Limited | Other services | 2022 |
| Magnastruck Ltd | Transport & logistics | 2022 |
| Magnolia Court Limited | Health & social care | 2005 |
| Mahal (Spring Grove) Limited | Real estate | 2025 |
| Mahal Construction UK Limited | Construction | 2021 |
| Mahal Holdings Limited | Financial services | 2023 |
| Mahal Properties Development Limited | Real estate | 2025 |
| Mahamed High Ticket Sales Ltd | Administrative & support | 2025 |
| Maharaj Ltd | Administrative & support | 2018 |
| Mahi Express Limited | Transport & logistics | 2025 |
| Mahrukh Ltd | Wholesale & retail | 2023 |
| Mahstyles Ltd | Wholesale & retail | 2025 |
| Maidan Brickwork Solutions Ltd | Construction | 2019 |
| Maiden Brickworks Ltd | Construction | 2022 |
| Maiden Contractors Ltd | Construction | 2022 |
| Maihan Commodities Limited | Wholesale & retail | 2010 |
| Main Unit Location Services Limited | Administrative & support | 2011 |
| Maina Freight Forwarders Limited | Transport & logistics | 1981 |
| Maina Imports Limited | Transport & logistics | 1995 |