| London Cartilage Clinic Ltd | Professional & scientific | 2025 |
| Long Strategic Property Ltd | Real estate | 2026 |
| Longhouse Design Ltd | Manufacturing | 2017 |
| Loom Sole Ltd | Wholesale & retail | 2025 |
| Louca Louca Limited | Construction | 2018 |
| Lovat & Co Professional Services LLP | | 2025 |
| Love & Lace Bridal Limited | Wholesale & retail | 2016 |
| Love Automatics Ltd | Wholesale & retail | 2019 |
| Love Yourself by Kellie Ltd | Other services | 2026 |
| LOW Farm Park Ltd | Hospitality | 2022 |
| Lowfields Leisure Limited | Hospitality | 2004 |
| LP Industries Limited | Construction | 2023 |
| Lrrb Holdings Limited | Real estate | 2024 |
| Ltce-Enterprises Ltd | Construction | 2024 |
| Lucky 47 Studios Ltd | Arts & recreation | 2009 |
| Lumen Diagnostics and Occupational Health Ltd | Transport & logistics | 2026 |
| Lumen Health Group Limited | Health & social care | 2026 |
| Lumen Lifestyle Support and Care Ltd | Health & social care | 2025 |
| Luna Installs Ltd | Construction | 2019 |
| LUX Clean Solutions Ltd | Administrative & support | 2025 |
| Luxe Model Management Ltd. | Administrative & support | 2024 |
| Luxury Nails 84 Ltd | Other services | 2022 |
| Lynchpin and Associates Limited | Administrative & support | 2013 |
| Lynx Consumables Limited | Wholesale & retail | 2025 |
| M & J Scaffolding Limited | Construction | 2002 |
| M Buck Property Services Ltd | Construction | 2016 |
| M L Groundworks Ltd | Construction | 2019 |
| M T & K R Properties Ltd | Real estate | 2022 |
| M&A Tyres Ltd | Wholesale & retail | 2020 |
| M-Fire Ltd | Public administration | 2011 |
| M.A. Craven (Donington) Limited | Arts & recreation | 1995 |
| M.C.Mountain and SON Limited | Agriculture & fishing | 1940 |
| MA Sports Coaching Ltd | Education | 2025 |
| MAC5 Consultants Ltd | Administrative & support | 2024 |
| Made at 8 Limited | Other services | 2021 |
| Magna Classics and Custom Limited | Wholesale & retail | 2026 |
| Maher Millard Ltd | Construction | 2010 |
| MAI Motion Ltd | Information & communication | 2024 |
| Mama Bear and Cubs Ltd | Wholesale & retail | 2020 |
| Manor Farm Shops Limited | Wholesale & retail | 2003 |
| Maplethorpe Game & Agri Ltd | Extraterritorial | 2021 |
| Mark Holmes Ltd | Arts & recreation | 2016 |
| Mark Massey Engineering Limited | Professional & scientific | 2026 |
| Marketing Success Ltd | Professional & scientific | 2025 |
| Marshall Keir Ltd | Construction | 2016 |
| Martin Osborne Design Services Limited | Professional & scientific | 2013 |
| Martin Osborne Holdings Limited | Real estate | 2020 |
| Martin Smith Paintwork & Restorations Limited | Wholesale & retail | 2020 |
| Martini Construction Ltd | Wholesale & retail | 2006 |
| Mastercraft (2021) Ltd | Wholesale & retail | 2021 |
| Matrix Consulting Solutions Limited | Professional & scientific | 2021 |
| Maughan & Sons Limited | Wholesale & retail | 2003 |
| MAX Enforcement Ltd | Public administration | 2022 |
| Maxlink Ltd | Hospitality | 2019 |
| Maya Indian Takeaway Ltd | Hospitality | 2017 |
| MBT Constructions Limited | Construction | 2016 |
| Mcgin-Lee HR Ltd | Professional & scientific | 2022 |
| Mcmillan Psychotherapy Limited | Health & social care | 2024 |
| Mcnulty Civils Ltd | Administrative & support | 2019 |
| MD4 Consulting Limited | Professional & scientific | 2022 |
| Mechanical Contracting Solutions Ltd | Professional & scientific | 2026 |
| Med-Eng Limited | Professional & scientific | 2012 |
| Melbourne Construction Limited | Construction | 2019 |
| Melbourne Food Group Limited | Manufacturing | 1994 |
| Melbourne Holdings Limited | Construction | 1979 |
| Melbourne Leisure Holdings Limited | Hospitality | 2018 |
| Melbourne Property Ltd | Real estate | 2023 |
| Menzies Medical Ltd | Health & social care | 2019 |
| Mercury Electronic Warfare Limited | Professional & scientific | 2009 |
| Meridian Walk Limited | Construction | 2022 |
| Merlin Capital Partners Ltd | Professional & scientific | 2018 |
| Miafk Limited | Hospitality | 2026 |
| Michael GUY Properties Limited | Real estate | 1975 |
| Midland County Construction Ltd | Construction | 2013 |
| Midland County Sectional Roofs Ltd | Construction | 2016 |
| Midlands Assess Ltd | Public administration | 2026 |
| Miguel Vieira Limited | Professional & scientific | 2018 |
| Miguelmateas Limited | Health & social care | 2016 |
| Mike Jones Training Co Limited | Professional & scientific | 2016 |
| Mikeng Ltd | Health & social care | 2024 |
| Military Vehicle Spares Limited | Wholesale & retail | 2016 |
| Millars Pumps Limited | Wholesale & retail | 2024 |
| Millstream Thai Limited | Hospitality | 2016 |
| Millthorpe Fields Management Company Limited | Water & waste | 2000 |
| Mini Rainbows (Murrayfield) Limited | Education | 2017 |
| Miro Signs Ltd | Professional & scientific | 2017 |
| Mise EN Place Limited | Professional & scientific | 2015 |
| Mitchell Maintenance Ltd | Real estate | 2025 |
| Mixed Pickle Limited | Information & communication | 2023 |
| Mixt Ltd | Health & social care | 2023 |
| MJI Training Limited | Professional & scientific | 2014 |
| MK Services 24H Ltd | Construction | 2021 |
| MKP Property Limited | Other services | 2019 |
| Mlgl Holdings Ltd | Real estate | 2025 |
| MM Automotive Ltd | Wholesale & retail | 2026 |
| Mntungwa Associates Limited | Hospitality | 2024 |
| Modern Vintage Models Ltd | Manufacturing | 2022 |
| Molstan Transport Ltd | Water & waste | 2017 |
| Money Minder Financial Services (Boston) Limited | Financial services | 2016 |
| Money Minder Financial Services (UK) Limited | Financial services | 2004 |