| Most Valuable Minds Film Production Ltd | Information & communication | 2018 |
| Mostyn House Leasehold Management Company Limited | Households | 2014 |
| Motalogic Limited | Wholesale & retail | 2024 |
| Mother Hubbards Croydon Limited | Hospitality | 2024 |
| Mother Hubbards Feast Ltd | Hospitality | 2024 |
| Mother Nutri Foods UK Ltd | Hospitality | 2015 |
| Mothers Care Ltd | Administrative & support | 2018 |
| Mothers Inspiring Angels Community Interest Company | Education | 2019 |
| Motherwell Care Ltd | Health & social care | 2019 |
| Motherwell Health Care Limited | Hospitality | 2024 |
| Motive Sports CIC | Arts & recreation | 2025 |
| Moto City Ltd | Wholesale & retail | 2016 |
| Motocom Limited | Administrative & support | 2002 |
| Motocom Properties Limited | Real estate | 2019 |
| Motol DOC Ltd | Wholesale & retail | 2026 |
| Motor Car Hub Ltd | Wholesale & retail | 2019 |
| Motor Smart Limited | Wholesale & retail | 2008 |
| Motorcycle Village Limited | Wholesale & retail | 1997 |
| Motorsmart London Ltd | Wholesale & retail | 2019 |
| Moumasi Properties Limited | Real estate | 2018 |
| Mount Ararat Road Management Company Limited | Households | 1968 |
| Mount Connaught Ltd | Administrative & support | 2012 |
| Mount Horeb Victorious Church International Ltd | Other services | 1999 |
| Mount View (Enfield) Management Company Limited | Households | 1990 |
| Mount Villas Management Company Limited | Households | 2002 |
| Mountain Interval LLP | | 2013 |
| Mountain Movers Ministries | Other services | 2019 |
| Mountain View Builders Ltd | Construction | 2023 |
| Mountbatten Mews Management Limited | Households | 2004 |
| Mountbatten Road Management Limited | Households | 1976 |
| Mountberry Ltd | Professional & scientific | 2024 |
| Mountsfield Gardens (NO 4) Management Limited | Households | 1997 |
| Mountwest UK Limited | Real estate | 2018 |
| Mourrya Limited | Information & communication | 2024 |
| Mouthy Media Ltd | Information & communication | 2017 |
| Move for YOU Removals Ltd | Transport & logistics | 2020 |
| Move IT ALL Removals Ltd | Transport & logistics | 2025 |
| Move Properties One Limited | Real estate | 2024 |
| Movement Careservices Ltd | Health & social care | 2014 |
| Movers Cleaning Ltd | Administrative & support | 2025 |
| Movex 360 Ltd | Transport & logistics | 2026 |
| Moving in OUT on Ltd | Transport & logistics | 2023 |
| Mowali Ltd | Wholesale & retail | 2024 |
| Mowbi Ltd | Professional & scientific | 2020 |
| Mowbray Apartments Management Company Limited | Households | 2022 |
| Moyami Ltd | Construction | 2019 |
| MP Cons Ltd | Construction | 2026 |
| MP Cybersecurity Limited | Information & communication | 2024 |
| MP Painter & Decorator Ltd. | Construction | 2016 |
| MP Trader Limited | Wholesale & retail | 2021 |
| MPG Groundworks Ltd | Construction | 2021 |
| Mposi Ltd | Health & social care | 2021 |
| MPP Music Publishing Ltd | Information & communication | 2021 |
| MPS AC & Renewables Ltd | Construction | 2026 |
| MPS Sports Management Ltd | Arts & recreation | 2014 |
| Mpwrd Ltd | Wholesale & retail | 2019 |
| MPX Consultancy Limited | Professional & scientific | 2026 |
| MR & MRS Yadav Ltd | Wholesale & retail | 2010 |
| MR Boyz Ltd | Other services | 2022 |
| MR Donnington RD Ltd | Real estate | 2026 |
| MR Jerk Catering Ltd | Hospitality | 2025 |
| MR JS REM Ltd | Hospitality | 2025 |
| MR Meat Halal Butchers and Grocers Limited | Wholesale & retail | 2021 |
| MR Monday to Friday Business Solutions Limited | Professional & scientific | 2025 |
| MR Moneyjar Limited | Education | 2019 |
| MR Mullans Limited | Other services | 2015 |
| MR Pitcroft Avenue Ltd | Real estate | 2026 |
| MR Pro Mobile Tech Ltd | Other services | 2024 |
| MR Tinto Limited | Hospitality | 2016 |
| MR. Prospect C.I.C. | Education | 2022 |
| Mr.K-Mas Ltd | Financial services | 2015 |
| Mrasta Limited | Professional & scientific | 2023 |
| Mrbk Ltd | Information & communication | 2021 |
| MRC Best Ltd | Health & social care | 2022 |
| Mrcarcabin Ltd | Transport & logistics | 2022 |
| Mreps Trustees (NO 47) Limited | Professional & scientific | 2003 |
| MRI Haque Limited | Hospitality | 2023 |
| MRI Management Group Ltd | Hospitality | 2025 |
| Mrks Global Ltd | Transport & logistics | 2022 |
| Mrlk Consulting Ltd | Professional & scientific | 2020 |
| MRM Coulsdon Ltd | Wholesale & retail | 2019 |
| MRM Retailers Ltd | Wholesale & retail | 2022 |
| MRM Whitgift Ltd | Wholesale & retail | 2018 |
| Mrnh Holdings Limited | Real estate | 2023 |
| Mrphonelondon Ltd | Wholesale & retail | 2023 |
| MRS Burney's BEE Club CIC | Education | 2021 |
| MRS. Pottsbury Limited | Wholesale & retail | 2026 |
| MRT Property Management Ltd | Households | 2023 |
| Mrta Services Ltd | Construction | 2022 |
| MRW Contractors Limited | Construction | 2022 |
| MS Building Group Ltd | Construction | 2020 |
| MS Digital Electronics Ltd | Wholesale & retail | 2023 |
| MS Ismart Cars Ltd | Wholesale & retail | 2023 |
| MS Loft Conversion Ltd | Construction | 2025 |
| MS Medical Services Ltd | Health & social care | 2018 |
| MS Planning & Design Ltd | Construction | 2024 |
| MS TVK Ltd | Professional & scientific | 2026 |
| MS Wholesale Distribution Ltd | Wholesale & retail | 2026 |
| Msaber Limited | Wholesale & retail | 2023 |
| Msamex Brokerage in Securities Listed in Foreign Markets Ltd | Financial services | 2025 |