| ML Racing Bloodstock Ltd | Agriculture & fishing | 2022 |
| MM Taxi Service Limited | Transport & logistics | 2025 |
| MMB Green Solutions Limited | Professional & scientific | 2026 |
| MMB Specialist Services Limited | Professional & scientific | 2025 |
| Mmclr Ltd | Transport & logistics | 2024 |
| Mmcsb Limited | Transport & logistics | 2017 |
| Mmiddleton Maintenance Ltd | Manufacturing | 2014 |
| Mmtm Properties Ltd | Real estate | 2025 |
| MN Global Logistic Ltd | Transport & logistics | 2024 |
| Mncrownsecurity Services Limited | Administrative & support | 2025 |
| MND Solution Ltd | Transport & logistics | 2024 |
| MNK Trans Ltd | Transport & logistics | 2015 |
| MNS Accident Repair Centre Limited | Wholesale & retail | 2000 |
| MNU Estate Ltd | Real estate | 2023 |
| MO Miller Ltd | Information & communication | 2022 |
| Mo-Star Tech Ltd | Information & communication | 2025 |
| Moavlo Limited | Real estate | 2013 |
| Mobile Welding Solutions Ltd | Manufacturing | 2020 |
| Mobile Wheel Clinic Ltd | Wholesale & retail | 2022 |
| Mobilise for Growth Group Limited | Professional & scientific | 2025 |
| Modern Practice Guidance Consultancy Ltd | Professional & scientific | 2025 |
| MODLAN69 Ltd | Professional & scientific | 2020 |
| Modora Store Limited | Wholesale & retail | 2026 |
| Moduhire Limited | Administrative & support | 2026 |
| Mogor Consulting Limited | Construction | 2024 |
| Moira Holdings Ltd | Financial services | 2023 |
| Moksh Property Investment Limited | Real estate | 2024 |
| Molter Ltd | Transport & logistics | 2024 |
| Moments 2 Memories Limited | Information & communication | 2026 |
| Monarch Knight Contracting Ltd | Construction | 2025 |
| Money for My Car Ltd | Wholesale & retail | 2019 |
| Mongold Ltd | Health & social care | 2022 |
| Monika Kuras Ltd | Other services | 2023 |
| Monty Smith Limited | Wholesale & retail | 2003 |
| Monument Court Management Company Limited | Households | 1990 |
| Monument London Limited | Wholesale & retail | 2022 |
| Moonlight Technology Limited | Extraterritorial | 2006 |
| Moore's Building and Restoration Ltd | Construction | 2017 |
| Moravian Engineering Limited | Professional & scientific | 2004 |
| More Events Ltd | Arts & recreation | 2016 |
| More Production Limited | Arts & recreation | 2005 |
| Morewood Plant Hire Limited | Construction | 2018 |
| Morgan Properties (Midlands) Limited | Real estate | 2023 |
| Morgann Enterprise's Limited | Hospitality | 2025 |
| Morlais Ltd. | Professional & scientific | 1997 |
| Morley & Scott Limited | Real estate | 2019 |
| Morley Design and Build Ltd | Construction | 2015 |
| Mosaic Workhouse Ltd | Wholesale & retail | 2021 |
| Motiva(C)Tion Ltd | Transport & logistics | 2024 |
| Motor Hydraulics Limited | Professional & scientific | 1946 |
| Motorazo Ltd | Wholesale & retail | 2025 |
| Mounts & More Ltd | Manufacturing | 2004 |
| MOV Engineering Ltd | Construction | 2026 |
| Move-It-Man Limited | Transport & logistics | 2021 |
| Moyo Hi-Tech Ltd | Health & social care | 2020 |
| MP PL Services Ltd | Wholesale & retail | 2017 |
| Mpgs Investments Limited | Financial services | 2026 |
| MR Barber's Decor Ltd | Wholesale & retail | 2022 |
| MR Cleaning Solutions Ltd | Administrative & support | 2010 |
| MR Mobile & Tech Limited | Wholesale & retail | 2023 |
| MR Road Hand Car Wash Ltd | Wholesale & retail | 2019 |
| MR Rooster Limited | Hospitality | 2018 |
| MR Scaffolding (UK) Limited | Construction | 2011 |
| MR. Buddy Pet Shop Limited | Wholesale & retail | 2022 |
| Mrcelery Limited | Wholesale & retail | 2026 |
| Mrci Limited | Real estate | 2016 |
| MRD Plant Ltd | Administrative & support | 2021 |
| MRJ Solutions Limited | Professional & scientific | 2017 |
| MRL Motoring Art Ltd | Arts & recreation | 2022 |
| MRM Group 2025 Limited | Professional & scientific | 2025 |
| MRM Group Holdings Limited | Financial services | 2023 |
| MRM Group Investment Limited | Construction | 2021 |
| MRM Group Limited | Construction | 2020 |
| MS Team & Co Ltd | Other services | 2014 |
| MSB Telecoms Ltd | Information & communication | 2025 |
| Msendame Corporation Ltd | Transport & logistics | 2015 |
| Mskes Ltd | Construction | 2026 |
| MSP International Ltd | Transport & logistics | 2022 |
| MT Creative Ltd | Arts & recreation | 2023 |
| MTA Supply Group Ltd | Transport & logistics | 2021 |
| MTB Transport Limited | Transport & logistics | 2022 |
| Mubarak Gifts Ltd | Wholesale & retail | 2026 |
| Mufaddal Enterprise Limited | Health & social care | 2019 |
| Mukhtar Property 786 Limited | Real estate | 2024 |
| Mulligan Brickwork and Maintenance Ltd | Construction | 2018 |
| Multi Roots Services Ltd | Agriculture & fishing | 2016 |
| Multi-Vision UK Limited | Construction | 1999 |
| Munene Limited | Wholesale & retail | 2021 |
| Muneris IT Limited | Information & communication | 2020 |
| Mur-Lec Electrical Contractors Limited | Construction | 2015 |
| Murray RIX Geotechnical Limited | Extraterritorial | 2019 |
| Murray RIX Limited | Professional & scientific | 2019 |
| Musa Ibrar Limited | Wholesale & retail | 2025 |
| Muse:Hr & Training Ltd | Professional & scientific | 2019 |
| Musgrove Investments Limited | Administrative & support | 2012 |
| Muslim Community Relations CIC | Professional & scientific | 2024 |
| Mustardgeo Ltd | Professional & scientific | 2022 |
| Mutt and Moggy Pet Shop Limited | Wholesale & retail | 2026 |
| Mutta Constructions Limited | Construction | 2020 |
| Mutta Professional Services Limited | Professional & scientific | 2021 |