| Miraj Films Creative Limited | Information & communication | 2020 |
| Miraj Films Limited | Information & communication | 2010 |
| Miraya Consultancy Limited | Information & communication | 2022 |
| MIS Concierge Ltd | Transport & logistics | 2023 |
| Mishu Limited | Administrative & support | 2013 |
| Misogi Health Limited | Health & social care | 2026 |
| Miss Birdi Ltd | Wholesale & retail | 2023 |
| Mister a T Autos Limited | Wholesale & retail | 2015 |
| Mitchell Production Limited | Arts & recreation | 2026 |
| Mitchla Management Limited | Construction | 2022 |
| Mitchla Marketing Ltd | Professional & scientific | 2012 |
| Mitnal Investigations Ltd | Professional & scientific | 2010 |
| Mivster Limited | Real estate | 2015 |
| MIX in Spirit Limited | Wholesale & retail | 2026 |
| Mixconcrete Holdings Limited | Professional & scientific | 1965 |
| Mixconcrete Limited | Professional & scientific | 1953 |
| Mixed Motion Ltd. | Arts & recreation | 2012 |
| Mixed Property Assets Limited | Real estate | 2013 |
| Miyazaki UK Ltd | Hospitality | 2014 |
| MJ Booze Ltd | Wholesale & retail | 2021 |
| MJ Property Developments Limited | Construction | 2011 |
| MJA Chase Consulting Ltd | Professional & scientific | 2014 |
| Mjak Property Development Ltd | Real estate | 2024 |
| MJD Carpentry Limited | Construction | 1996 |
| Mjgfitness Ltd | Professional & scientific | 2021 |
| Mjjn Ltd | Real estate | 2022 |
| MJL Electrical Installations Ltd | Construction | 2008 |
| MJO Property Agents Ltd | Real estate | 2023 |
| MJP Kitchens and Electrical Ltd | Other services | 2012 |
| MK Beauty Saloon Limited | Other services | 2026 |
| MK Berkshire Limited | Transport & logistics | 2024 |
| MK Fitness Ltd | Arts & recreation | 2026 |
| MK Sohi Ltd | Health & social care | 2017 |
| MK9 Security Ltd | Financial services | 2022 |
| MKB Residential Limited | Real estate | 2025 |
| Mklt Consultancy Limited | Transport & logistics | 2019 |
| MKR Webtech Ltd | Information & communication | 2022 |
| MKS Brickwork Ltd | Construction | 2025 |
| MLK Impact Marketing Services Limited | Professional & scientific | 2025 |
| MLS Natural Product Consultancy Limited | Wholesale & retail | 2021 |
| MM Studio Design Ltd | Professional & scientific | 2017 |
| Mm&P & Co Ltd | Financial services | 2025 |
| MMA Corporation Ltd | Construction | 2024 |
| MMK Innovation Ltd | Information & communication | 2025 |
| MMK Telecom Limited | Professional & scientific | 2017 |
| MNH Homez Limited | Real estate | 2018 |
| Mnry Investments Ltd | Real estate | 2022 |
| Mobile & Wireless (UK) Limited | Administrative & support | 2006 |
| Mobile Help Mechanics Ltd | Professional & scientific | 2025 |
| Mobile Tekniks Limited | Wholesale & retail | 2021 |
| Mobilus Limited | Administrative & support | 2001 |
| MOD Home Improvements Ltd | Construction | 2011 |
| Modal AV Ltd | Information & communication | 2019 |
| Modal Energy Limited | Construction | 2022 |
| MODE5 Ltd | Professional & scientific | 2015 |
| Model Farm Management Limited | Construction | 2011 |
| Modern Music Education Ltd | Education | 2026 |
| Modus Financial Solutions UK Ltd | Professional & scientific | 2023 |
| Moga Limited | Transport & logistics | 2025 |
| Mogad Solidarity Foundation | Information & communication | 2026 |
| Mohammed Rafiq Consultancy Ltd | Health & social care | 2020 |
| Mohan LAL Orthopaedic Services Ltd | Health & social care | 2010 |
| Moka Finance Ltd | Financial services | 2019 |
| Mokitte Trade Marks Ltd | Professional & scientific | 2024 |
| Molberry Limited | Professional & scientific | 2026 |
| Mollington Co. Limited | Professional & scientific | 2018 |
| Moment of Life Ltd | Arts & recreation | 2016 |
| Momentum Portfolio Property Limited | Real estate | 2024 |
| Monax Tech Limited | Wholesale & retail | 2020 |
| Monch Bidco Limited | Financial services | 2021 |
| Monch Midco Limited | Financial services | 2021 |
| Monch Topco Limited | Financial services | 2021 |
| Monellohairdressing Limited | Other services | 2026 |
| Moneyrow Beans Ltd | Manufacturing | 2020 |
| Monkey Madness Limited | Extraterritorial | 2016 |
| Monkey Muay Thai Ltd | Arts & recreation | 2015 |
| Monovale Properties Limited | Real estate | 1971 |
| Monox Group Ltd | Professional & scientific | 2026 |
| Monroc Limited | Real estate | 2024 |
| Monster Medical Limited | Extraterritorial | 2016 |
| Montague Freehold Limited | Real estate | 2013 |
| Montemerch Ltd | Wholesale & retail | 2025 |
| Monterroso Consulting Limited | Information & communication | 2017 |
| Mood Health Ltd | Health & social care | 2024 |
| Mood Interiors LLP | | 2016 |
| Moogbrew Ltd | Manufacturing | 2014 |
| Moonbeam Tech Investments Limited | Extraterritorial | 2021 |
| Moongate Ltd | Professional & scientific | 2025 |
| Moonglade Group Limited | Financial services | 2025 |
| Moorbridge House Ltd | Real estate | 2025 |
| Moore Accounting Services Ltd | Professional & scientific | 2011 |
| Moores Homes Ltd | Construction | 2022 |
| Moorethan Consulting Ltd | Information & communication | 2025 |
| Moorland Way Consulting Limited | Information & communication | 2021 |
| Moorside Garage Limited | Wholesale & retail | 1986 |
| Moorstud Farm Ltd | Administrative & support | 2020 |
| Moorstud Ltd | Professional & scientific | 2022 |
| Morage Management Ltd | Professional & scientific | 2023 |
| Morden Plus Ltd | Wholesale & retail | 2025 |
| Morebeat Limited | Professional & scientific | 1981 |