| Logolicious Ltd | Information & communication | 2020 |
| Lokman Liais Ltd | Education | 2025 |
| London Islamic Capital Limited | Financial services | 2025 |
| Longevity Clinical Ltd | Health & social care | 2022 |
| Longevity IQ Limited | Health & social care | 2023 |
| Lrsvn Ltd | Real estate | 2025 |
| LRT Heating Ltd | Construction | 2013 |
| Lucas and Lucas Ltd | Professional & scientific | 2021 |
| Luee Limited | Wholesale & retail | 2026 |
| Lunar E-Learning Academy Limited | Education | 2022 |
| M&E Transport Ltd | Transport & logistics | 2007 |
| M.A.D. Investment Holding Limited | Manufacturing | 2020 |
| M.F Property Improvement Limited | Construction | 2022 |
| M.L. Sellitto Holding Limited | Financial services | 2024 |
| M11 Vehicle Services Limited | Wholesale & retail | 2013 |
| M3 Estates Limited | Real estate | 2016 |
| M4 Estates Limited | Real estate | 2017 |
| M5 Estates Limited | Administrative & support | 2017 |
| MA Lucas Ltd | Health & social care | 2021 |
| Macca Design Limited | Construction | 2014 |
| Maceldon Education Ltd | Education | 2022 |
| Made Group Limited | Education | 2020 |
| Made Lettings Ltd | Real estate | 2023 |
| Made Structures Ltd | Construction | 2024 |
| Magic Equine Assisted Therapy C.I.C. | Health & social care | 2023 |
| Maia Leisure Limited | Arts & recreation | 2016 |
| Maid Magic Ltd | Administrative & support | 2026 |
| Makilla Audio Ltd | Information & communication | 2026 |
| Mallett Productions Ltd | Information & communication | 2025 |
| Mandorlo Services Limited | Professional & scientific | 2023 |
| Mane (UK) Limited | Wholesale & retail | 1983 |
| Manfrica Family | Education | 2023 |
| Marke Wasteaway Limited | Water & waste | 2026 |
| Marketing Compliance Associates Limited | Other services | 2020 |
| Marra Properties Ltd | Real estate | 2021 |
| Masala Takeaway Broxbourne Ltd | Hospitality | 2020 |
| Massdan Limited | Real estate | 2003 |
| Master Knifeman Limited | Professional & scientific | 2020 |
| Master Scaffolding Ltd | Construction | 2015 |
| Match ME Swimwear Ltd | Wholesale & retail | 2022 |
| MAX H Limited | Construction | 2026 |
| Mazi Broxbourne Limited | Hospitality | 2025 |
| Mazi Cafe Limited | Hospitality | 2024 |
| MCK Property & Energy Limited | Real estate | 2015 |
| Mckenzie Royce Ltd | Information & communication | 2023 |
| Mcpake Properties Ltd | Real estate | 2026 |
| MCS Sports Limited | Other services | 2009 |
| MD Baldwin Consulting Limited | Professional & scientific | 2016 |
| MD Projects Glendee Limited | Construction | 2026 |
| MD Projects London Limited | Construction | 2015 |
| MD Projects Wimbledon Limited | Real estate | 2015 |
| MDA Autos Ltd | Wholesale & retail | 2025 |
| MDF Advisory Limited | Professional & scientific | 2019 |
| Mdsquared Limited | Professional & scientific | 2010 |
| Mebek Ltd | Professional & scientific | 2021 |
| Meesha Ltd | Wholesale & retail | 2026 |
| Memorials of Distinction Ltd | Manufacturing | 2022 |
| Mercury Couriers Limited | Transport & logistics | 2018 |
| Merih Arif Limited | Wholesale & retail | 2024 |
| Messy Media Limited | Information & communication | 2021 |
| Metro Meat Products Ltd | Wholesale & retail | 2019 |
| MG1 Limited | Real estate | 2023 |
| Micana Inc Limited | Information & communication | 2014 |
| Michail Medical Ltd | Health & social care | 2009 |
| Middleton Legal Limited | Professional & scientific | 2021 |
| Middleton Partners Limited | Professional & scientific | 2020 |
| Mighty YOU Ltd | Other services | 2022 |
| Mijie Ltd | Health & social care | 2020 |
| Mikaliana Apartments Ltd | Real estate | 2024 |
| Millapede Ltd | Professional & scientific | 2016 |
| MIN Trading AS Good Choice 8 Ltd | Hospitality | 2026 |
| Mithu & Achu Food Ltd | Hospitality | 2023 |
| Mithu & Achu Ltd | Real estate | 2023 |
| MJR2 Ltd | Construction | 2026 |
| MKJ Food Limited | Hospitality | 2024 |
| ML Infiniti Properties Ltd | Real estate | 2024 |
| MN FIX Ltd | Construction | 2019 |
| Moashfoods Limited | Wholesale & retail | 2022 |
| Modern Industrial Technology Group Ltd | Financial services | 2019 |
| Mokate Food Ltd | Wholesale & retail | 2020 |
| Molmans Limited | Real estate | 2018 |
| Moore Wellness Ltd | Health & social care | 2021 |
| Moreton Dairy Limited | Wholesale & retail | 2005 |
| Moreton Freehold Limited | Households | 2021 |
| Moretto Brothers Limited | Manufacturing | 1977 |
| Mountstep Group Limited | Wholesale & retail | 2024 |
| MPG Construction Ltd | Construction | 2010 |
| MPM Connect 2 Limited | Extraterritorial | 2021 |
| MPM Connect Limited | Professional & scientific | 2010 |
| MR Tanaka's Ltd | Administrative & support | 2017 |
| MRDJ2K Limited | Real estate | 2025 |
| MS Brickwork Limited | Construction | 2013 |
| MS Estates Limited | Real estate | 2015 |
| MSD Estates Limited | Construction | 2005 |
| MSW Tech Ltd | Information & communication | 2014 |
| MT Catering Herts Ltd | Wholesale & retail | 2025 |
| MTI Accounting Solutions Limited | Professional & scientific | 2010 |
| Much Hadham Estate Management Limited | Households | 2017 |
| MVM Consultants Limited | Construction | 2012 |
| My Fine Ltd | Wholesale & retail | 2019 |