| Mmmk Drylining Limited | Construction | 2010 |
| MMS Family Investments Ltd | Real estate | 2021 |
| MMS Smart Limited | Construction | 2019 |
| MNA Property Group Limited | Real estate | 2024 |
| Moaa Services Limited | Health & social care | 2023 |
| Mobile Surveillance Vehicles Group Limited | Professional & scientific | 2017 |
| Mobilecarers Limited | Health & social care | 2018 |
| Mobilitybase Limited | Construction | 2014 |
| Mobilynx Healthcare Services Limited | Health & social care | 2019 |
| Mobilynx Limited | Construction | 2015 |
| Mobilynx Projects Limited | Construction | 2023 |
| Mobs Ventures Ltd | Information & communication | 2007 |
| Moco Tech Ltd | Information & communication | 2011 |
| Modern Accounting Ltd | Professional & scientific | 2022 |
| Modern Alarms Limited | Other services | 2010 |
| Modern Bathrooms Ltd | Construction | 2020 |
| Modium Developments Limited | Construction | 2001 |
| Modtrad Zinc Roofing Ltd | Construction | 2020 |
| Mogaino Ltd | Wholesale & retail | 2024 |
| Mohan Realty Ltd | Real estate | 2022 |
| Mohani Estates Limited | Real estate | 2025 |
| Mojac Software Limited | Information & communication | 2026 |
| MOKE92021 Limited | Real estate | 2024 |
| Moldotrans Ltd | Transport & logistics | 2025 |
| Molives Ltd | Professional & scientific | 2018 |
| Mollward Ltd | Financial services | 2019 |
| Molpat Ltd | Extraterritorial | 2016 |
| Momiji Properties Limited | Real estate | 2025 |
| Momist Limited | Hospitality | 2025 |
| MON Universe Ltd | Wholesale & retail | 2022 |
| Monax Entertainment Ltd | Arts & recreation | 2024 |
| Money Monster Limited | Wholesale & retail | 2020 |
| Monform Limited | Construction | 2022 |
| Monitor Cleaning Services Limited | Administrative & support | 1990 |
| Monitor Hygiene Services Limited | Administrative & support | 2000 |
| Monitor Services Limited | Administrative & support | 1991 |
| Mono Nexo Ltd | Professional & scientific | 2024 |
| Monochrome Homes Lettings Ltd | Other services | 2022 |
| Monochrome Homes Sales Ltd | Other services | 2022 |
| Monotechnical Limited | Professional & scientific | 2013 |
| Monro Design Studio Ltd | Professional & scientific | 2020 |
| Monte Group Holding Ltd | Wholesale & retail | 2017 |
| Monument Group Holdings Ltd | Construction | 2019 |
| Monzah Limited | Real estate | 2026 |
| MOO Consultancy Ltd | Professional & scientific | 2025 |
| Moonbeam Property Ltd | Real estate | 2024 |
| Moonbow Properties Limited | Real estate | 2021 |
| Moonstars Nursery Limited | Education | 2024 |
| Mooreshalom Ltd. | Health & social care | 2014 |
| Moove Lubricants Limited | Manufacturing | 1986 |
| Mora Transport Limited | Transport & logistics | 2015 |
| Moraks Limited | Health & social care | 2010 |
| More Collins Ltd | Health & social care | 2021 |
| More Soon Services Ltd | Wholesale & retail | 2025 |
| Morg Ltd | Hospitality | 2019 |
| Morh Services Limited | Other services | 2026 |
| Morris & Steed Limited | Wholesale & retail | 2007 |
| Morris Cleaning Limited | Other services | 2003 |
| Morrow Bridging Ltd | Financial services | 2026 |
| Morrow Money Ltd | Administrative & support | 2019 |
| Mortgage Sense Limited | Financial services | 2015 |
| Mortgage-Eez (Kent) Limited | Financial services | 2001 |
| Mortlake 17 LLP | | 2016 |
| Mosero Automotive 121 Ltd | Wholesale & retail | 2020 |
| Mosero Limited | Wholesale & retail | 2019 |
| Moses Cosmetic Ltd | Wholesale & retail | 2026 |
| Mosflo Ltd | Health & social care | 2009 |
| Moss & Mortar Limited | Real estate | 2025 |
| Moss-Me Ltd | Wholesale & retail | 2025 |
| Motason Group Ltd | Construction | 2025 |
| Mothada Records Ltd | Wholesale & retail | 2025 |
| Motor Racing Ltd | Wholesale & retail | 2024 |
| Motorosi Service Ltd | Wholesale & retail | 2015 |
| Mount Edgecumbe Limited | Hospitality | 2019 |
| Mount Express Services Limited | Transport & logistics | 2006 |
| Mount Pleasant Dawlish Ltd | Hospitality | 2023 |
| Mount Shaw Limited | Real estate | 2025 |
| Move Your Car Ltd | Transport & logistics | 2022 |
| Movebuilder Ltd | Construction | 2024 |
| Moveswithmaci Ltd | Other services | 2024 |
| Moyo Salawu Ltd | Information & communication | 2022 |
| MPC Cars 1 Limited | Wholesale & retail | 2025 |
| MPP Electrical Ltd | Construction | 2015 |
| MQ Autoparts Ltd | Wholesale & retail | 2026 |
| MR Construction Contractors Ltd | Construction | 2020 |
| MR FIX ALL Ltd | Other services | 2023 |
| MR Gills Investments Ltd | Real estate | 2024 |
| MR Possible Services and Logistics Limited | Transport & logistics | 2025 |
| MR. Morris & Partners Limited | Other services | 1981 |
| MRI (London) Limited | Construction | 1997 |
| Mrik Properties Ltd | Real estate | 2018 |
| MRJ Care Limited | Health & social care | 2018 |
| MRM Trans Ltd | Transport & logistics | 2018 |
| MRP Direct Limited | Wholesale & retail | 2004 |
| MRV Limited | Transport & logistics | 2014 |
| MS Cabling Services Ltd | Construction | 2023 |
| MS Drives & Patios Ltd | Construction | 2023 |
| MS Music Limited | Education | 2013 |
| MS Property Development Ltd | Construction | 2016 |
| MS RAJ Construction Ltd | Construction | 2024 |