| Lmcs Consulting Ltd | Professional & scientific | 2022 |
| Lmoceans Limited | Professional & scientific | 2024 |
| Lo-Lite Limited | Information & communication | 2000 |
| Loam Consulting Ltd | Financial services | 2008 |
| Lodgelegal Ltd | Professional & scientific | 2024 |
| LOG10 Ltd | Information & communication | 2021 |
| London Executive Protection Ltd | Administrative & support | 2018 |
| London Liver Cancer Clinic Ltd | Health & social care | 2019 |
| London Night OUT Limited | Other services | 2025 |
| London Prestige Chauffeur Services Ltd | Other services | 2008 |
| London Road Properties Limited | Real estate | 2013 |
| Londtra Limited | Professional & scientific | 2021 |
| Lone Brothers Property Limited | Real estate | 2023 |
| Lone Care Services Ltd | Health & social care | 2014 |
| Loopdigital.Ai Ltd | Information & communication | 2020 |
| Lorena Oberg Skincare Ltd. | Other services | 2012 |
| Lothbury Consultants Limited | Professional & scientific | 2010 |
| Lothbury Financial Services Limited | Administrative & support | 2009 |
| Loungelato Limited | Wholesale & retail | 2024 |
| Love a List Ltd | Information & communication | 2025 |
| Lovehenri Ltd | Health & social care | 2013 |
| Loving Moments Ltd | Administrative & support | 2016 |
| Loxford Way Management Co. Ltd. | Real estate | 2015 |
| Loxwood Place Management Company Limited | Households | 2019 |
| LPD Development Consulting Limited | Professional & scientific | 2023 |
| LPD Fire Ltd | Public administration | 2022 |
| LRT Electrical Surrey Ltd | Construction | 2021 |
| LSJ Landscapes Limited | Administrative & support | 2024 |
| LSW Property Developments Limited | Real estate | 2017 |
| LT Illustration Limited | Arts & recreation | 2016 |
| Ltd Consultancy Limited | Professional & scientific | 2025 |
| Lthc Development Ltd | Administrative & support | 2024 |
| Lumehn CIC | Information & communication | 2026 |
| Lumen Aeris Limited | Construction | 2019 |
| Lumma LLP | | 2020 |
| Luvlulu's Boutique Limited | Wholesale & retail | 2017 |
| LUX Build Developments Ltd | Construction | 2020 |
| Luxe Good Limited | Professional & scientific | 2012 |
| Luxudent Limited | Financial services | 2022 |
| Luxury Car Transport Ltd | Transport & logistics | 2024 |
| LW4G Limited | Professional & scientific | 2024 |
| Lytecode Ltd | Information & communication | 2018 |
| M & J Flavours Limited | Hospitality | 2025 |
| M a H Maintenance Limited | Construction | 2003 |
| M C Fencing & Decking Limited | Administrative & support | 2019 |
| M J Gillespie Decorators Limited | Construction | 2014 |
| M&D Cleanco Ltd | Administrative & support | 2025 |
| M&M Asset Ventures Limited | Real estate | 2025 |
| M&M Fitters Ltd | Construction | 2016 |
| M. Crowe Scaffold Services Limited | Construction | 2002 |
| M.C. Bristow Limited | Agriculture & fishing | 1983 |
| M.G. Wealth Management Limited | Administrative & support | 2007 |
| M.Harris Rail Services Limited | Construction | 2013 |
| M.J.Fisher & Co LLP | | 2014 |
| MAC 4 Action Hire Limited | Professional & scientific | 1989 |
| MAC Maintenance Limited | Construction | 2024 |
| Macbeth Landscaping Limited | Administrative & support | 2003 |
| Macdonald Motorsport Limited | Manufacturing | 2015 |
| Macdonald PMO Consulting Ltd | Information & communication | 2025 |
| Macdonald Software Consulting Limited | Information & communication | 2013 |
| Mach K Ltd | Professional & scientific | 2020 |
| Made for Life Foundation | Other services | 2010 |
| MAHTCORP1 Limited | Professional & scientific | 2021 |
| Maidwell Marketing Ltd | Professional & scientific | 2015 |
| Make a Noise Ltd | Professional & scientific | 2020 |
| Making Maps Work Limited | Arts & recreation | 2003 |
| Makkam Limited | Construction | 2024 |
| Malabar World Limited | Hospitality | 2025 |
| Malta Lettings Limited | Administrative & support | 2003 |
| Mamba Clothing Ltd | Other services | 2025 |
| Mamjrn Ltd | Construction | 2022 |
| Manage-Tec Proprietary Limited | Professional & scientific | 2017 |
| Manilva (Contracts) Limited | Construction | 1992 |
| Manilva Properties Limited | Real estate | 2008 |
| Manilva Properties London Limited | Real estate | 2025 |
| Manning Holdings Limited | Other services | 2020 |
| Manor Trading Limited | Hospitality | 2021 |
| MAP Waterproofing Limited | Construction | 2026 |
| Marali Childcare Ltd | Health & social care | 2023 |
| Marine and Diesel Engineering Services Ltd | Manufacturing | 2025 |
| Mark Frost Plumbing & Heating Ltd | Construction | 2010 |
| Mark Jordan Architecture & Design Limited | Administrative & support | 2012 |
| Mark Millard Limited | Professional & scientific | 2009 |
| Mark Otoole Limited | Transport & logistics | 2010 |
| Mark Winsbury Consulting Ltd | Professional & scientific | 2013 |
| Marketair Ltd | Professional & scientific | 2018 |
| Marketing Alliance Group Ltd. | Information & communication | 2016 |
| Marksup Limited | Education | 2025 |
| Marlborough Mews Partnership | | 1987 |
| Marlborough Mews Partnership II | | 1988 |
| Marlone Footwear Limited | Wholesale & retail | 1967 |
| Marlone Shoes Limited | Wholesale & retail | 1963 |
| Marlowe Commerce Limited | Hospitality | 2012 |
| Marmo Stucco Ltd | Construction | 2015 |
| Marnik Projects Limited | Construction | 2013 |
| Marshall Light Studio Ltd | Professional & scientific | 2017 |
| Martin Homes Davigdor Road Ltd | Real estate | 2021 |
| Martin Homes Hurstpierpoint Ltd | Construction | 2020 |
| Martin Homes Redhill Ltd | Real estate | 2020 |
| Maru Global Limited | Other services | 2023 |