| Luvent Brilliance Ltd | Wholesale & retail | 2024 |
| Luxeadmin Ltd | Professional & scientific | 2024 |
| LW Ltd | Extraterritorial | 2009 |
| LX Limited | Extraterritorial | 2014 |
| Lyn-Lem Properties Ltd | Real estate | 2023 |
| Lynwood Associates Ltd | Professional & scientific | 2002 |
| Lynwood House Properties Ltd | Construction | 2012 |
| Lynwood House Property Management LLP | | 2020 |
| M & H Haulage Limited | Extraterritorial | 2011 |
| M & N Hire Limited | Administrative & support | 2013 |
| M a Agencies Limited | Wholesale & retail | 2014 |
| M C Webb & SON Limited | Water & waste | 2005 |
| M Dodkin Consultancy Limited | Information & communication | 2007 |
| M J Bakery Limited | Manufacturing | 2020 |
| M J Pipe Limited | Wholesale & retail | 1998 |
| M L Partnership Landscaping Limited | Administrative & support | 2003 |
| M Q Services (UK) Ltd | Real estate | 2005 |
| M Tunstill Limited | Financial services | 2023 |
| M&R Lewis Estates Ltd | Real estate | 2026 |
| M.L.W. Bell Racing Limited | Professional & scientific | 1993 |
| M3 Media Global Ltd | Professional & scientific | 2022 |
| Macer Limited | Financial services | 2023 |
| Macintyre Transport Limited | Transport & logistics | 2000 |
| Made by Sonny Limited | Information & communication | 2024 |
| Magnolia Bloodstock Limited | Agriculture & fishing | 2026 |
| Magnolia Property Limited | Construction | 2025 |
| Main Ambition Limited | Professional & scientific | 2023 |
| Maja Agencies Ltd | Wholesale & retail | 2026 |
| Malik Trans Ltd | Manufacturing | 2015 |
| Malton Golf Limited | Administrative & support | 2008 |
| Managing Capital Limited Liability Partnership | | 2008 |
| Mann + Vogel Ltd | Professional & scientific | 2026 |
| Manners Capital Limited | Real estate | 2018 |
| Manor Farm Construction Limited | Construction | 2020 |
| Manor Properties Investments Limited | Real estate | 2015 |
| Marblewood Bespoke Interiors Ltd | Construction | 2016 |
| Marbury Technical Services Ltd | Construction | 2024 |
| Marco Botti Ltd | Arts & recreation | 2005 |
| Marco Ghiani Ltd | Professional & scientific | 2023 |
| Marcstown Ltd | Agriculture & fishing | 2024 |
| Marginplay Ltd | Information & communication | 2025 |
| Margot 1936 Limited | Other services | 2023 |
| Marjoram Properties (BSE) Limited | Real estate | 2025 |
| Mark and EVA Bloodstock LLP | | 2018 |
| Mark Edmondson Limited | Professional & scientific | 2012 |
| Mark James Art Limited | Wholesale & retail | 2019 |
| Markies Marquees Ltd | Administrative & support | 2018 |
| Marp Consultancy Ltd | Professional & scientific | 2012 |
| Martin Dunne Racing Limited | Administrative & support | 2022 |
| MARTINJOBS77 Ltd | Manufacturing | 2022 |
| Marventi Ltd | Professional & scientific | 2017 |
| Mason Construction Group Ltd | Construction | 2025 |
| Master Gardener Limited(The) | Professional & scientific | 1985 |
| Mastering Awareness Limited | Professional & scientific | 2021 |
| Matahorn Ltd | Agriculture & fishing | 2019 |
| Mathilde Texier Limited | Professional & scientific | 2015 |
| Matt Crawley Racing Ltd | Agriculture & fishing | 2023 |
| Matthew Lyes Garden Services Limited | Other services | 2003 |
| Maxse Communications Limited | Professional & scientific | 2010 |
| Maxtrain Global Ltd | Professional & scientific | 2025 |
| Maxx Catley Ltd | Professional & scientific | 2022 |
| Mayfair Construction (Cambridge) Ltd | Construction | 2020 |
| Maze Bloodstock Limited | Arts & recreation | 2020 |
| MB Electrical Ltd | Construction | 2024 |
| Mcbride Assets Limited | Real estate | 2016 |
| Mcculloughs Limited | Energy | 2005 |
| Mcdaid Housing Limited | Real estate | 2020 |
| Mcgeorge Creations Limited | Information & communication | 2025 |
| Mcgivern Property Ltd | Real estate | 2025 |
| Mckeever Bloodstock Ltd | Administrative & support | 2010 |
| Mckinleys Group Holdings Ltd | Financial services | 2022 |
| Mckinleys Group Trading Ltd | Wholesale & retail | 2016 |
| Mckinleys Holdings Ltd | Financial services | 2024 |
| Mckinleys Property Ltd | Financial services | 2024 |
| MCW Hospitality 2 Ltd | Hospitality | 2026 |
| MCW Hospitality Ltd | Hospitality | 2024 |
| MD Smallholdings Ltd | Hospitality | 2025 |
| MDB Services Limited | Information & communication | 2021 |
| Mdsign Internet Services Limited | Information & communication | 2011 |
| ME Lash Ltd | Wholesale & retail | 2021 |
| Medlar Houses Limited | Real estate | 2008 |
| Medtech Partners Ltd | Professional & scientific | 2026 |
| Meerkat PR Limited | Administrative & support | 2009 |
| Megaprop Limited | Real estate | 2017 |
| Melcon Services Limited | Construction | 1995 |
| Melmedia Limited | Information & communication | 2026 |
| Melville Bay Ltd | Mining & quarrying | 2010 |
| Merchants Place Management Company (ELY) Limited | Households | 2006 |
| Merlcot Housing Association Ltd | Hospitality | 2014 |
| Mertoun Estate Farms Limited | Agriculture & fishing | 2000 |
| Mertoun Properties Limited | Financial services | 2025 |
| Mertoun Services Limited | Administrative & support | 2019 |
| Metroinns 1 Limited | Hospitality | 2025 |
| Metroinns 2 Limited | Hospitality | 2025 |
| MHE Electronics Limited | Manufacturing | 2008 |
| MHJ Electrical Limited | Construction | 2025 |
| Michael Keady Racing Limited | Arts & recreation | 2024 |
| Michael Murphy Pre-Training Ltd | Agriculture & fishing | 2019 |
| Micky Fenton Racing Limited | Arts & recreation | 2026 |
| Middle Park Stud Limited | Real estate | 2019 |