| LT Medicals Ltd | Health & social care | 2022 |
| LTG Group Limited | Wholesale & retail | 2019 |
| Ltorg Limited | Information & communication | 2013 |
| LU Properties Limited | Real estate | 2021 |
| Lucian Mihai Ltd | Construction | 2018 |
| Lucie Houchin Creative Limited | Information & communication | 2026 |
| Lucky Bones Ltd | Professional & scientific | 2026 |
| Lukasz Stawarz Ltd | Transport & logistics | 2021 |
| Lukaszb Ltd | Transport & logistics | 2018 |
| Lumenstone Ltd | Real estate | 2025 |
| Lumos Clinic Limited | Other services | 2021 |
| Luna Safety Group Ltd | Administrative & support | 2024 |
| Lunahub Limited | Wholesale & retail | 2026 |
| Lunar Broking Services Ltd | Financial services | 2022 |
| Lunar Mail Ltd | Arts & recreation | 2020 |
| Luoxing Technologies Limited | Information & communication | 2015 |
| Lupe Business Solutions Ltd | Wholesale & retail | 2025 |
| Lupus Transport Ltd | Transport & logistics | 2017 |
| Lutley IQ Limited | Information & communication | 2009 |
| Luux Two Limited | Professional & scientific | 2010 |
| Luxcutz Limited | Other services | 2026 |
| Luxesoft Ltd | Information & communication | 2024 |
| Luxus Stays Limited | Real estate | 2024 |
| Luzannah Healthcare Ltd | Health & social care | 2015 |
| LV Technical Services Ltd | Construction | 2023 |
| Lynn Road Dental Practice Limited | Health & social care | 2008 |
| L’Illa Holdings Limited | Professional & scientific | 2023 |
| M & H2 Associates Limited | Administrative & support | 2006 |
| M and H Steel Fabrications Ltd | Manufacturing | 2009 |
| M Angold Services Ltd | Construction | 2026 |
| M D Henshaw Construction Ltd | Construction | 2023 |
| M J Saunders Consultancy Ltd | Professional & scientific | 2017 |
| M L Gundry Scaffolding Limited | Construction | 2012 |
| M Mitchell Construction Ltd | Construction | 2018 |
| M N Fashion Ltd | Wholesale & retail | 2022 |
| M N Steeden Plumbing & Heating Limited | Construction | 2012 |
| M&D Wealth Management Limited | Financial services | 2020 |
| M&E Property Associates Ltd | Construction | 2025 |
| M&M Roofing Ltd | Construction | 2022 |
| M&T Roofing Ltd | Construction | 2024 |
| M.A.D. to Make a Difference Limited | Professional & scientific | 2018 |
| M.C. Pegg Plumbing, Heating & GAS Ltd | Manufacturing | 2017 |
| M.E.Percival Decorator Ltd | Construction | 2026 |
| M.N Electrical and Building Services Ltd | Construction | 2025 |
| M.P Brickwork & Building Services Limited | Construction | 2025 |
| M.W. Accounting Ltd | Professional & scientific | 2000 |
| M3 Automation Limited | Construction | 2021 |
| M3 User Association | Information & communication | 2005 |
| M923 Consulting Ltd | Professional & scientific | 2017 |
| MA Business Solutions Ltd | Professional & scientific | 2021 |
| Maabos Ltd | Wholesale & retail | 2024 |
| Maash Consultants Ltd | Other services | 2018 |
| MAC Project Oversight Ltd | Construction | 2026 |
| MAC Property Funding Ltd | Financial services | 2014 |
| Macdonald Stephens Limited | Information & communication | 2002 |
| Machabwa Ltd | Health & social care | 2025 |
| Macintosh Legal & Financial Services Limited | Financial services | 2019 |
| Macintyre Hudson Worldwide Ltd. | Extraterritorial | 2007 |
| Macmillan Children's Books Limited | Extraterritorial | 1979 |
| Macmillan Direct Limited | Extraterritorial | 1984 |
| Macmillan Publishers International Limited | Information & communication | 1986 |
| MAD Trans Ltd | Transport & logistics | 2025 |
| Madalin Driving Ltd | Transport & logistics | 2025 |
| Maddsuperstore Limited | Wholesale & retail | 2018 |
| Made 4 U Leather Limited | Wholesale & retail | 2024 |
| Madebypaid Ltd. | Professional & scientific | 2024 |
| Madina Halal Supermarket Limited | Wholesale & retail | 2026 |
| Madiza Limited | Real estate | 2022 |
| Madone Enterprises Limited | Information & communication | 2025 |
| Maestro Development Group Ltd | Education | 2026 |
| MAF Associates Limited | Professional & scientific | 2012 |
| MAG IT Solutions Limited | Information & communication | 2006 |
| Maggsy's Home Improvements Ltd | Construction | 2025 |
| Magic Pro Cleaning Ltd | Administrative & support | 2014 |
| Magus Accountancy Ltd | Professional & scientific | 2018 |
| Maharani Employment Services Limited | Administrative & support | 2020 |
| Mahasan Ltd | Hospitality | 2026 |
| Maid in Basingstoke Limited | Administrative & support | 2012 |
| Mailosaur Ltd | Information & communication | 2012 |
| Main Computer Systems Limited | Information & communication | 2014 |
| Main Excellent CUT Ltd | Other services | 2021 |
| Maison DE Choup Limited | Wholesale & retail | 2016 |
| Majestic Manes Ltd | Other services | 2025 |
| Majestic Spice House Limited | Hospitality | 2025 |
| MAK Insight Ltd | Information & communication | 2012 |
| Maka Designs Limited | Professional & scientific | 2016 |
| Make Social Ltd | Professional & scientific | 2018 |
| Make Unique Limited | Manufacturing | 2024 |
| Making Numbers Talk Ltd | Extraterritorial | 2013 |
| Malden Risk Solutions Limited | Financial services | 2025 |
| Malilani Global Metals Ltd | Wholesale & retail | 2025 |
| Mallards Wood Education Ltd | Education | 2015 |
| Mallards Wood Group Ltd | Education | 2003 |
| Mallards Wood Property Limited | Real estate | 2016 |
| Malm Holdings Ltd | Manufacturing | 2026 |
| Malthouse Bridge Limited | Professional & scientific | 2019 |
| Mamajays Food Ltd | Manufacturing | 2020 |
| Mamayana Ltd | Wholesale & retail | 2025 |
| Mammir Ltd | Real estate | 2017 |
| Managed Training Services Limited | Professional & scientific | 1993 |