| Lumley Hill Consulting Ltd | Professional & scientific | 2026 |
| Luna Consultancy Limited | Administrative & support | 2009 |
| Lunatistic Ltd | Extraterritorial | 2012 |
| Lund House Management Limited | Households | 2003 |
| Lupins (Middlesbrough) Ltd | Hospitality | 2026 |
| Luscombe Gray Ltd | Professional & scientific | 2018 |
| Luxe Line for Trade Ltd | Information & communication | 2020 |
| Luxealu Ltd | Wholesale & retail | 2023 |
| Luxedent Ltd | Health & social care | 2026 |
| Luxhux Media Ltd | Arts & recreation | 2024 |
| Luxury Beauty HG1 Ltd | Other services | 2026 |
| Luxury Beauty Spa Ltd | Other services | 2025 |
| Luxury Lifestyle Group Limited | Real estate | 2017 |
| Lvcollett Limited | Other services | 2020 |
| Lybtech Limited | Professional & scientific | 2009 |
| Lydan Global Ltd | Wholesale & retail | 2025 |
| LYN Consulting Limited | Administrative & support | 2009 |
| Lynd Products Limited | Professional & scientific | 2011 |
| Lynn Warren Consultants Ltd | Professional & scientific | 2021 |
| Lynx Dynamics Limited | Extraterritorial | 2025 |
| Lynx FM Limited | Extraterritorial | 2025 |
| Lynx Medical Limited | Extraterritorial | 2026 |
| Lynx Menswear Limited | Wholesale & retail | 2002 |
| Lynx Womenswear Limited | Wholesale & retail | 2005 |
| Lyon Landscapes Limited | Administrative & support | 2007 |
| Lypso Limited | Wholesale & retail | 2024 |
| Lzdb Limited | Information & communication | 2017 |
| M & D Business Consultants Limited | Professional & scientific | 2020 |
| M & D Investment Group Limited | Transport & logistics | 2026 |
| M & D Leasing Limited | Administrative & support | 2026 |
| M & S Brearton Ltd | Hospitality | 2017 |
| M Break Ltd | Extraterritorial | 2025 |
| M C Capital Holdings Limited | Financial services | 2024 |
| M Duerden Electrical Limited | Construction | 2023 |
| M K Reporting Ltd | Health & social care | 2019 |
| M P D Quantity Surveying Limited | Professional & scientific | 2011 |
| M P F Holdings Ltd | Financial services | 2019 |
| M S Cunningham Ltd | Energy | 2012 |
| M U R Precision Developments Limited | | 1990 |
| M. & S. Hire Limited | Extraterritorial | 1984 |
| M. D. R. Decorators Limited | Construction | 1979 |
| M. Epoch Limited | Hospitality | 2018 |
| M. Sutton Decorators Ltd | Construction | 2006 |
| M.A.D. Design Co. Limited | Administrative & support | 1999 |
| M.E Education Ltd | Education | 2025 |
| M.H. Whittaker & SON Limited | Construction | 1978 |
| M.I. Ward Enterprises Ltd | Construction | 2009 |
| M1 LF Ltd | Extraterritorial | 2015 |
| M1CHAEL Limited | Extraterritorial | 2020 |
| M1CHELLE Limited | Extraterritorial | 2022 |
| M1DAS Ltd | Extraterritorial | 2019 |
| M1KE Ltd | Extraterritorial | 2016 |
| M2MGUBBINS Limited | Information & communication | 2020 |
| M4RC Ltd | Extraterritorial | 2017 |
| M4RCO Ltd | Extraterritorial | 2017 |
| MA LO Creative Ltd | Professional & scientific | 2025 |
| MA Shangyun for Investment Ltd | Wholesale & retail | 2024 |
| MA UK Builders Ltd | Construction | 2025 |
| Maatsen Properties Limited | Real estate | 2025 |
| Mabie Todd Limited | Wholesale & retail | 2017 |
| Mabo Capital Holding Ltd | Financial services | 2024 |
| MAC Capital Holdings Ltd | Financial services | 2018 |
| Macallam Limited | Administrative & support | 2000 |
| Maccafferty LLP | | 2012 |
| Maccafferty Plastics Limited | Financial services | 2001 |
| Macdougall Investment Ltd | Real estate | 2023 |
| Macey Construction Limited | Construction | 2014 |
| Machina Engineering Ltd | Manufacturing | 2026 |
| Maclean Architecture Ltd | Professional & scientific | 2015 |
| Macleod Property Ltd | Real estate | 2025 |
| Macvanta Advisory Limited | Professional & scientific | 2026 |
| Macvanta Resources Limited | Professional & scientific | 2025 |
| MAD1SON Limited | Extraterritorial | 2026 |
| Madala Limited | Financial services | 2015 |
| Madani Pro Company Ltd | Wholesale & retail | 2021 |
| Madbel Limited | Manufacturing | 2013 |
| Maddison Education Consultancy Limited | Education | 2015 |
| Maddock Limited | Extraterritorial | 2026 |
| Made by Two Ltd | Professional & scientific | 2021 |
| Made Scents Limited | Extraterritorial | 2013 |
| Madeley Property Ltd | Real estate | 2020 |
| Madhatters Dining Room Ltd | Hospitality | 2023 |
| MAG1C Ltd | Wholesale & retail | 2021 |
| Magicdust Consulting Limited | Professional & scientific | 2020 |
| Magictiger Limited | Real estate | 2023 |
| Magnolia Box Limited | Wholesale & retail | 2006 |
| Magnus Civil Engineering Ltd | Construction | 2023 |
| MAH Garden Maintenance Limited | Administrative & support | 2010 |
| Maid at Home Interiors Ltd | Wholesale & retail | 2024 |
| Mail Order DOT COM Ltd | Extraterritorial | 2012 |
| Main Site Farm Dalton Limited | Construction | 2024 |
| Main Street Homes Limited | Real estate | 2021 |
| Maineside Management Company Limited | Households | 2004 |
| Maison Group Limited | Extraterritorial | 2025 |
| Maitland Manor Thoroughbred Racing Ltd. | Professional & scientific | 2007 |
| MAJ1D Limited | Extraterritorial | 2020 |
| MAJEST1C Limited | Wholesale & retail | 2023 |
| Majestic Court (Harrogate) Owners Association | Households | 1989 |
| Majestic Facilities Limited | Extraterritorial | 2025 |
| Majestic Gateway Limited | Extraterritorial | 2022 |