| Magic Wills Ltd | Professional & scientific | 2025 |
| Magical Nails Ltd | Other services | 2023 |
| Magical Whiz Limited | Wholesale & retail | 2023 |
| Magical Whizz Limited | Wholesale & retail | 2020 |
| Magicare Services Ltd | Health & social care | 2020 |
| Magmo Ltd | Transport & logistics | 2024 |
| Magna Fidus Solutions Ltd | Other services | 2018 |
| Magna Lettings Limited | Real estate | 2015 |
| Magnatrax Ltd | Wholesale & retail | 2025 |
| Magnet UK Consultancy Limited | Professional & scientific | 2017 |
| Magnum Transport Ltd | Transport & logistics | 2015 |
| Magratonics Ltd | Professional & scientific | 2022 |
| Magunje Limited | Health & social care | 2021 |
| Maha Shahzad Ltd | Wholesale & retail | 2026 |
| Mahal Group Ltd | Real estate | 2024 |
| Mahal Stores Ltd | Wholesale & retail | 2023 |
| Mahal Tavern Ltd | Hospitality | 2023 |
| Mahan Solutions Ltd | Wholesale & retail | 2018 |
| Maharani B Limited | Hospitality | 2025 |
| Maharani Hampton Limited | Hospitality | 2019 |
| Maharanis of Deeping Ltd | Hospitality | 2008 |
| Mahav Crest Ltd | Real estate | 2025 |
| Mahdi Pharma Services Ltd | Health & social care | 2016 |
| Maheed International Ltd | Real estate | 2016 |
| Maia Drive Ltd | Transport & logistics | 2021 |
| Maiafreight Ltd | Transport & logistics | 2025 |
| Mailmarque Ltd | Manufacturing | 2022 |
| Main Stage Ltd | Administrative & support | 2025 |
| Mainard JR Limited | Wholesale & retail | 2016 |
| Mainline Lifting Equipment Limited | Extraterritorial | 2007 |
| Mainline Vehicle Auction Ltd | Wholesale & retail | 2026 |
| Mainspring Enterprises Ltd | Information & communication | 2016 |
| Mainstrim Consortium UK Ltd | Transport & logistics | 2022 |
| Maintenance 24 7 Limited | Administrative & support | 2003 |
| Maison DE LA Bride Ltd | Wholesale & retail | 2010 |
| Maison DE MAY Beauty Ltd | Other services | 2025 |
| Maison Flavours Ltd | Hospitality | 2026 |
| MAJ 275 Ltd | Professional & scientific | 2023 |
| Maja Asset Management Ltd | Financial services | 2023 |
| Majestic Kesari Limited | Administrative & support | 2024 |
| Majestic Lettings Limited | Real estate | 2014 |
| Majid Investments Group Ltd | Wholesale & retail | 2025 |
| Majikrose Limited | Wholesale & retail | 2025 |
| MAK Building & Electric Maintenance Ltd | Construction | 2019 |
| MAK Knight Ltd | Financial services | 2021 |
| MAK Trans Ltd | Transport & logistics | 2023 |
| MAK Windows & Doors Ltd | Manufacturing | 2025 |
| Maka Market Ltd | Wholesale & retail | 2025 |
| Makarios Cleaning Services Ltd | Administrative & support | 2025 |
| Makati Express Cargo Ltd | Transport & logistics | 2020 |
| Make a Difference (UK) Limited | Health & social care | 2002 |
| Make Real Progress Ltd | Professional & scientific | 2021 |
| Makel Holdings Ltd | Administrative & support | 2021 |
| Makhmal Doctors Ltd | Health & social care | 2025 |
| Makkahs Autos Ltd | Wholesale & retail | 2024 |
| Makkaly Ecom Ltd | Wholesale & retail | 2025 |
| Makkan International Limited | Health & social care | 2015 |
| Mako Driving Ltd | Transport & logistics | 2015 |
| Maks 123 Ltd | Wholesale & retail | 2025 |
| Maksa Ltd | Manufacturing | 2013 |
| Makx Developments Limited | Real estate | 2019 |
| Malax Ltd | Wholesale & retail | 2021 |
| Malcolm James & Partners Estate Agents Limited | Extraterritorial | 2004 |
| Malcolm James & Partners Property Rentals Limited | Real estate | 2004 |
| Malcolm Leigh Decorating Limited | Construction | 2003 |
| Maleesa Limited | Information & communication | 2010 |
| Malel Ltd | Health & social care | 2019 |
| Malewski Ltd | Transport & logistics | 2025 |
| Malick & Co Limited | Professional & scientific | 2008 |
| Malletti Ltd | Wholesale & retail | 2026 |
| Malrat Foods Ltd | Hospitality | 2014 |
| Malsa Ltd | Other services | 2019 |
| MAM INT UK Ltd | Real estate | 2020 |
| MAM UK Properties Ltd | Real estate | 2023 |
| Mama's Embrace 4U Ltd | Administrative & support | 2024 |
| Mama's Embrace Community Interest Company | Health & social care | 2024 |
| Mamal Limited | Transport & logistics | 2016 |
| Mambo Arts Ltd | Arts & recreation | 2025 |
| Mamde Ltd | Health & social care | 2023 |
| Mamm Properties Limited | Real estate | 2006 |
| Mammoth Workwear Limited | Manufacturing | 2022 |
| Mamos Super Market Ltd | Wholesale & retail | 2025 |
| MAN International Limited | Information & communication | 2016 |
| Manab Ltd | Administrative & support | 2026 |
| Manage Plant (Peterborough) Limited | Wholesale & retail | 2020 |
| Manage Plant Limited | Wholesale & retail | 2011 |
| Management Company 10 Vantage Park Limited | Households | 2009 |
| Mandaa Property Limited | Real estate | 2025 |
| Mandairs Estate Agents Ltd | Real estate | 2017 |
| Mandalay Park Limited | Wholesale & retail | 2024 |
| Mandric Ltd | Transport & logistics | 2023 |
| Manduria Developments Limited | Construction | 2001 |
| Mandy Ashton Consultants Limited | Professional & scientific | 2014 |
| Mane Services Ltd | Construction | 2017 |
| Mangadze Ltd | Health & social care | 2016 |
| Mangla Catering Services Ltd | Hospitality | 2024 |
| Mango Global Ltd | Professional & scientific | 2024 |
| Mango Heating Ltd | Construction | 2024 |
| Mangold Investments Ltd | Financial services | 2006 |
| Mangwa Holdings Ltd | Wholesale & retail | 2026 |