| Losco Ltd | Manufacturing | 2024 |
| Loungetox Limited | Other services | 2017 |
| Love Open Water Ltd | Arts & recreation | 2018 |
| Love Outdoors Group Limited | Administrative & support | 2017 |
| Love Sport Events Limited | Arts & recreation | 2016 |
| Love That Group Ltd | Professional & scientific | 2018 |
| Lowndes House Developments Ltd | Construction | 2019 |
| LOX O'Fire Ltd | Administrative & support | 2025 |
| LP Fire Protection Ltd | Other services | 2017 |
| LP Medics Limited | Health & social care | 2013 |
| LRG Consultancy Limited | Professional & scientific | 1990 |
| Lrvn Ltd | Wholesale & retail | 2022 |
| LTA Properties Ltd | Real estate | 2019 |
| Luca 25 Ltd | Transport & logistics | 2025 |
| Lucas Kingshill Limited | Construction | 2017 |
| Lucennio Consultancy Limited | Information & communication | 2024 |
| Lucennio Property Limited | Construction | 2024 |
| Lucky B Limited | Transport & logistics | 2023 |
| Lusi Holidays Ltd | Other services | 2017 |
| LUX Stylish Limited | Information & communication | 2014 |
| Luxeletterbox Ltd | Wholesale & retail | 2025 |
| Lxry Competitions Ltd | Arts & recreation | 2025 |
| Lxry Ltd | Professional & scientific | 2021 |
| Lycrome Limited | Administrative & support | 2013 |
| LYE Green Management Company Limited | Households | 2003 |
| Lyndhurst Plant Limited | Administrative & support | 1997 |
| Lynwood Construction Limited | Construction | 2000 |
| Lynx Software Limited | Information & communication | 2007 |
| M & a Thai Ltd | Hospitality | 2018 |
| M & G MAY Consulting Ltd | Administrative & support | 2007 |
| M & P Construction Services Limited | Extraterritorial | 2002 |
| M a Shadbolt Building Services Limited | Construction | 2006 |
| M Abdulkader & Sons Ltd | Financial services | 2020 |
| M and T Training Ltd | Education | 2022 |
| M Aston and SON Roofing Ltd | Construction | 2014 |
| M Denham Carpentry and Construction Ltd | Manufacturing | 2026 |
| M Kelsey Ltd | Professional & scientific | 2021 |
| M M B Chesham Ltd | Wholesale & retail | 2019 |
| M T Motors (Chesham) Ltd | Wholesale & retail | 2013 |
| M!Ladys Ltd | Wholesale & retail | 2025 |
| M&Ab Management Ltd | Professional & scientific | 2026 |
| M&T Cleaning Services Ltd | Administrative & support | 2025 |
| M-I Arif Ltd | Professional & scientific | 2016 |
| M-Team Ltd | Construction | 2014 |
| M4Z Dynamic Deals Ltd | Wholesale & retail | 2025 |
| Machine Polishing Services Ltd | Manufacturing | 2019 |
| Maclaran Trends Global Limited | Wholesale & retail | 2019 |
| Madame DE Chocolat Ltd | Manufacturing | 2023 |
| Maddogg Designs Ltd | Other services | 2023 |
| Madhura Limited | Manufacturing | 2025 |
| MAE LEE Aesthetics Ltd | Other services | 2025 |
| Maghella Limited | Construction | 2004 |
| Magnacrest Construction Limited | Construction | 2018 |
| Mail Handling Solutions Ltd | Administrative & support | 2024 |
| Majr Events Ltd | Administrative & support | 2025 |
| Malaphor Whisky Ltd | Manufacturing | 2019 |
| Maloti Investments Limited | Real estate | 2017 |
| Malvern Villas Limited | Households | 1997 |
| Mandeville Place (Amersham) Ltd | Real estate | 2026 |
| Maneeya Thai Spa Ltd | Health & social care | 2025 |
| Manor Electrical Wholesale Ltd | Wholesale & retail | 2020 |
| Manor Signs (UK) Limited | Manufacturing | 2013 |
| Mapkidz Ltd | Real estate | 2012 |
| Maple Valley Equestrian Centre Ltd | Agriculture & fishing | 2024 |
| Maple Valley T/A Fredericks Removals Ltd | Transport & logistics | 2017 |
| Marabu Production Limited | Information & communication | 2026 |
| Marcell’S Organic Soup Limited | Hospitality | 2023 |
| Marcus Graham Ltd | Information & communication | 2015 |
| Mares M Construction Ltd | Construction | 2026 |
| Margosa Environmental Solutions Ltd | Professional & scientific | 2012 |
| Maria Kennedy Consulting Limited | Professional & scientific | 2025 |
| Mark Auto Electrics Ltd | Wholesale & retail | 2005 |
| Mark Barnes Plumbing & Heating Ltd | Construction | 2007 |
| Market Square Glazing Solutions Limited | Construction | 2019 |
| Marotech Ltd | Construction | 2014 |
| Marquis Connections Ltd | Administrative & support | 2025 |
| Marsh Works Ltd | Other services | 2013 |
| Marshall NO 10 Portland Property Limited | Real estate | 2021 |
| Marshall NO 68 Danum Property Limited | Real estate | 2022 |
| Marshall Portland Property Limited | Real estate | 2025 |
| Martec Europe Investments Limited | Real estate | 2013 |
| Martec Europe Limited | Professional & scientific | 1991 |
| Martin Coppola Ltd | Other services | 2021 |
| Marz Enterprise Ltd | Financial services | 2025 |
| Masarati Consulting Ltd | Professional & scientific | 2021 |
| Masintelligence Ltd | Hospitality | 2018 |
| Masons Court Residents Association Limited | Households | 1973 |
| Masters Financial Planning Ltd | Financial services | 2007 |
| Mastersol Limited | Information & communication | 2017 |
| Mavencery Ltd | Information & communication | 2021 |
| Mavensys Limited | Information & communication | 2017 |
| Mawdsley Safety Limited | Professional & scientific | 2015 |
| MAX Capital Finance Ltd | Financial services | 2024 |
| Maximised Holdings Limited | Administrative & support | 2022 |
| Maximus Purus Ltd | Administrative & support | 2026 |
| Maxmarque Limited | Professional & scientific | 2012 |
| Maxted Park Management Company Limited | Real estate | 2016 |
| Maxwell Digital Studio Ltd | Information & communication | 2026 |
| Maxwyn Ltd | Information & communication | 2025 |
| Maydin Ecommerce Trade Ltd | Wholesale & retail | 2019 |