| Lumina Electrical Limited | Construction | 2025 |
| Lumio Media Ltd | Information & communication | 2025 |
| Lummina Ltd | Health & social care | 2019 |
| Lumora Events Ltd | Administrative & support | 2024 |
| Luna-Versal Ltd | Arts & recreation | 2026 |
| Lunar Sea Developments (UK) Limited | Real estate | 2003 |
| Lunar Sea Holdings (UK) Limited | Real estate | 2003 |
| Lupa Foods Ltd | Wholesale & retail | 2003 |
| Lure Movie Ltd | Information & communication | 2021 |
| Lush Moments Ltd | Professional & scientific | 2025 |
| LUV Apps Limited | Information & communication | 2018 |
| LUV Corp Ltd | Wholesale & retail | 2013 |
| LUV Digital Development Ltd | Information & communication | 2017 |
| LUX Chauffeur Services Ltd | Transport & logistics | 2025 |
| Luxe Carpets and Flooring Ltd | Wholesale & retail | 2024 |
| Luxury Apartment Rentals Limited | Professional & scientific | 2020 |
| Luxury Deals Trading Limited | Wholesale & retail | 2023 |
| Luxury Glass Design Ltd | Construction | 2023 |
| Luxury RV Chauffeur Ltd | Transport & logistics | 2026 |
| LV Assets Management Ltd | Real estate | 2025 |
| Lvlt Ltd | Real estate | 2014 |
| LVS Automotive Engineering Ltd | Manufacturing | 2019 |
| LVW Investment Holdings Ltd | Real estate | 2022 |
| LVW Property Brixton Hill Ltd | Real estate | 2022 |
| LVW Property Cobham Ltd | Real estate | 2022 |
| LW Sales Limited | Wholesale & retail | 2025 |
| LW Wells Prophand Services Ltd | Information & communication | 2011 |
| Lwbm Limited | Professional & scientific | 2014 |
| Lymm Car Wash & Valet Ltd | Administrative & support | 2024 |
| Lynda Investments LLP | | 2026 |
| Lyndrian Investments | Financial services | 2025 |
| Lynn Transport Ltd | Transport & logistics | 2005 |
| Lyntonwood Limited | Professional & scientific | 1996 |
| Lynx Corporation Ltd | Hospitality | 2015 |
| Lyon Road Properties Limited | Real estate | 2019 |
| Lyreal Estate Ltd | Real estate | 2023 |
| Lyttelton Limited | Administrative & support | 2012 |
| Lytton Road Limited | Real estate | 2016 |
| LZ Capital Limited | Real estate | 2014 |
| M & D Rendering Ltd | Construction | 2019 |
| M & M Global Developments Limited | Construction | 2017 |
| M & P Direct Limited | Wholesale & retail | 2000 |
| M & T Partition & Ceiling Ltd | Construction | 2011 |
| M a Drylining & Plastering Ltd | Construction | 2018 |
| M a Holdings & Investments Ltd | Real estate | 2022 |
| M B S Bathrooms & Kitchens (UK) Limited | Wholesale & retail | 2011 |
| M Bridges Amersham Limited | Administrative & support | 2020 |
| M Connect Ltd | Information & communication | 2018 |
| M Crawley Limited | Construction | 2017 |
| M Cristea Ltd | Construction | 2022 |
| M Electrical Works Ltd | Construction | 2014 |
| M Gilders Roofing Contracts Limited | Construction | 2008 |
| M Graves Ltd | Administrative & support | 2018 |
| M J & a Partners Ltd | Real estate | 2018 |
| M J Hall Construction Ltd | Construction | 2005 |
| M Kotecha Limited | Wholesale & retail | 2007 |
| M N B Electrical Limited | Other services | 2007 |
| M P Painters & Decorators Ltd | Construction | 2019 |
| M Prabhakar Healthcare Ltd | Health & social care | 2021 |
| M S Physiocare Ltd | Health & social care | 2025 |
| M Shumbusho Ltd | Health & social care | 2021 |
| M Tech Installation Services Ltd | Professional & scientific | 2016 |
| M&C General Services Ltd | Transport & logistics | 2017 |
| M&G Family Ltd | Manufacturing | 2023 |
| M&L Brisley Ltd | Professional & scientific | 2025 |
| M&M Brewery Limited | Hospitality | 2026 |
| M&M Dragonfly Limited | Transport & logistics | 2015 |
| M&M Property Division Ltd | Real estate | 2025 |
| M&S Dosani Properties Limited | Real estate | 2017 |
| M&S Electricals Ltd | Construction | 2009 |
| M&S Express Couriers Ltd | Transport & logistics | 2019 |
| M&S IP Ltd | Information & communication | 2016 |
| M. & J. Lossos & Co. Limited | Construction | 1938 |
| M. Galleria International Limited | Real estate | 2024 |
| M. Long Haulage & Daughters Limited | Construction | 2010 |
| M. Long Holdings Limited | Professional & scientific | 2015 |
| M.Fox Electrics Limited | Construction | 2010 |
| M.W. Interiors Ltd | Manufacturing | 2018 |
| M18MLK Ltd | Real estate | 2025 |
| M2CONSTRUCTIONLTD Ltd | Construction | 2024 |
| MA & MG Holdings Ltd | Extraterritorial | 2026 |
| MA Office Services Limited | Administrative & support | 2023 |
| Maantha Limited | Manufacturing | 2013 |
| MAC Autos Body Shop Ltd | Wholesale & retail | 2026 |
| Macd Trading Limited | Administrative & support | 2010 |
| Macfarlane Studios Ltd | Real estate | 2020 |
| Macius Ltd | Wholesale & retail | 2011 |
| Mackay & SON Building Services & Maintenance Ltd | Construction | 2026 |
| Macks Solutions Ltd | Construction | 2023 |
| Macro Engineering Limited | Professional & scientific | 1980 |
| Macwell Locarno Limited | Construction | 2014 |
| MAD Monk TV Ltd | Information & communication | 2006 |
| Madden Logistics Ltd | Transport & logistics | 2009 |
| Made by Ness Ltd | Professional & scientific | 2021 |
| Made in Little France Import Limited | Wholesale & retail | 2014 |
| Madelaine Leech Ltd | Information & communication | 2023 |
| Madman Limited | Wholesale & retail | 2014 |
| Maebi Ltd | Financial services | 2021 |
| Maeland Consulting Ltd | Professional & scientific | 2019 |
| MAG Haulage Limited | Transport & logistics | 2022 |