| Merakivirtualservices Ltd | Health & social care | 2019 |
| Merdos Kebab Limited | Hospitality | 2025 |
| Meridian Data Solutions Limited | Professional & scientific | 2017 |
| Meridyens Investment Ltd | Construction | 2024 |
| Merit Risk Management and Consultancy Ltd | Professional & scientific | 2015 |
| Merry Gardens Developments Limited | Construction | 2023 |
| Mert Tutors Ltd | Education | 2025 |
| Metisys Ltd | Information & communication | 2026 |
| Metro Property Developers Ltd | Construction | 2020 |
| Metropol Media Limited | Information & communication | 2009 |
| MF Accounting & Taxation Limited | Professional & scientific | 2018 |
| MF Homes Ltd | Households | 2023 |
| MFA Hala Ltd | Hospitality | 2026 |
| MFA Plumbing and Heating Limited | Construction | 2016 |
| MFM Prayer City Church Ltd | Other services | 2021 |
| MGH Skyline Build Ltd | Construction | 2026 |
| MGP Property Limited | Real estate | 2000 |
| MH Manor Limited | Real estate | 2024 |
| Mia-Tech and Logistics Ltd | Transport & logistics | 2025 |
| Miah Apartments Ltd | Real estate | 2020 |
| MIC International Ltd | Information & communication | 2025 |
| Micaman Services Ltd | Water & waste | 2020 |
| Micart (Holdings) LLP | | 2009 |
| Micart Development Limited | Wholesale & retail | 2014 |
| Micart LLP | | 2008 |
| Michael Gerard Electrical Supplies Limited | Extraterritorial | 2008 |
| Michael Gerard Limited | Extraterritorial | 2008 |
| Michael Idowu Ltd | Professional & scientific | 2021 |
| Michael Kumar Limited | Information & communication | 2018 |
| Michael Mcgahern Construction Ltd | Administrative & support | 2017 |
| Michael Motors Limited | Wholesale & retail | 2025 |
| Michelle Bassam Psychological Therapist Limited | Health & social care | 2010 |
| Michelle Pinnock-Troupe Limited | Professional & scientific | 2014 |
| Microprolab Ltd | Wholesale & retail | 2018 |
| Micul Londonez Ltd | Hospitality | 2025 |
| Mielis Capital Limited | Financial services | 2024 |
| Mien Group Ltd | Real estate | 2024 |
| Mightee Construction Ltd | Construction | 2018 |
| Mike&Nic Ltd | Construction | 2019 |
| Milay Ltd | Hospitality | 2024 |
| Miles Brothers Building & Civil Engineering Ltd | Construction | 2025 |
| Miles Builders (Hertfordshire) Ltd | Construction | 2009 |
| Mill Regeneration Ltd | Manufacturing | 2009 |
| Miller Imports and Exports Limited | Other services | 2024 |
| Miller X Limited | Wholesale & retail | 2021 |
| Millyworldhealth Solution Ltd | Administrative & support | 2022 |
| Milr Properties Limited | Construction | 2016 |
| Mima Company Ltd | Transport & logistics | 2009 |
| Mind & Body Works Limited | Transport & logistics | 2025 |
| Mind Focus Counselling Limited | Health & social care | 2019 |
| Mindov & Co Ltd | Administrative & support | 2017 |
| Mini Manes Ltd | Other services | 2015 |
| Mini Morgans Nursery Limited | Health & social care | 2025 |
| Mint and Mint Limited | Other services | 2024 |
| Mint Green Group Holdings Limited | Construction | 2024 |
| Minx Investments Limited | Real estate | 2024 |
| Mirablau Limited | Professional & scientific | 2021 |
| Miracle Massage Ltd | Administrative & support | 2019 |
| Misol Solutions Limited | Information & communication | 2021 |
| Missing Link Care Training & Recruitment Consultants Ltd. | Health & social care | 2020 |
| Mistry Residential Ltd | Real estate | 2026 |
| Mitchelson Consultancy Services Limited | Professional & scientific | 2026 |
| Mithraic Limited | Administrative & support | 2021 |
| Mitu Costruct Ltd | Construction | 2021 |
| Miyamaya Limited | Health & social care | 2022 |
| MJA Comms Ltd | Information & communication | 2019 |
| MJB Creative Building Contractors Ltd | Construction | 2021 |
| MJC Group Ltd | Financial services | 2025 |
| MJC Investment Group Limited | Professional & scientific | 2019 |
| MJO Property Portfolio Ltd | Real estate | 2026 |
| MJP Building London Limited | Other services | 2022 |
| MK Access Scaffolding Limited | Construction | 2016 |
| MK Bazaar North Ltd | Wholesale & retail | 2025 |
| MK Media Group Ltd | Professional & scientific | 2025 |
| Mkag Media Ltd | Information & communication | 2023 |
| ML Autotech Ltd | Professional & scientific | 2025 |
| ML Legal Ltd | Professional & scientific | 2026 |
| ML Translation Ltd | Professional & scientific | 2026 |
| MM & Freight Services Limited | Other services | 2026 |
| Mm&D Ltd | Other services | 2015 |
| MMI TB Limited | Construction | 2015 |
| MMP Consultancy Limited | Administrative & support | 2013 |
| MMP Support Services Ltd | Administrative & support | 2016 |
| Mnjc Property Ltd | Real estate | 2025 |
| MO Snaps Ltd | Information & communication | 2017 |
| Mo's Motorcycles Ltd | Wholesale & retail | 2016 |
| Mobile Windscreen Repair and Replacement Limited | Wholesale & retail | 2019 |
| MOD Games CIC | Arts & recreation | 2025 |
| Modest Roots Ltd | Other services | 2025 |
| Modtec Limited | Administrative & support | 1993 |
| MOH Cleaner Ltd | Administrative & support | 2022 |
| Moia Services Limited | Information & communication | 2015 |
| Mojid Estates Limited | Real estate | 2026 |
| Mojid Homes Limited | Real estate | 2026 |
| Mojos MA Limited | Hospitality | 2025 |
| MOL Construct Ltd | Construction | 2024 |
| Moment Together Residential Limited | Real estate | 2024 |
| MON Divine Limited | Administrative & support | 2024 |
| Monarch Films Ltd | Information & communication | 2020 |
| Monarch S & M Ltd | Real estate | 2025 |