| LL Hair Extensions Ltd | Wholesale & retail | 2025 |
| Llamedos Investments Limited | Real estate | 2017 |
| Llewellyn Shipping Company Limited | Professional & scientific | 2020 |
| LMA Consultant Services Limited | Professional & scientific | 2016 |
| LMD Skip Hire Limited | Water & waste | 2015 |
| Lmnry Capital Limited | Financial services | 2024 |
| Locate in Kent Limited | Administrative & support | 1996 |
| Lockdutton Corporate Finance Limited | Administrative & support | 2021 |
| Lodestone 1452 Limited | Professional & scientific | 2017 |
| Lodestone Partners Limited | Administrative & support | 2010 |
| Loftus Digital Ltd | Other services | 2025 |
| Logical Intent International Limited | Other services | 2013 |
| Logistica Systems Limited | Information & communication | 1997 |
| Logosky UK Limited | Other services | 2024 |
| LOK Ltd | Wholesale & retail | 2026 |
| Lola Jones Ltd | Wholesale & retail | 2011 |
| Londas Tech Limited | Information & communication | 2026 |
| Londinium Management Services Limited | Professional & scientific | 2007 |
| Londinium Services Limited | Transport & logistics | 2006 |
| London Arts Discovery Limited | Other services | 2021 |
| London BUS Museum Ltd | Wholesale & retail | 2006 |
| London BUS Preservation & Repair Ltd | Wholesale & retail | 2010 |
| London Calling Events Ltd | Other services | 2010 |
| London City Break Ltd | Hospitality | 2011 |
| London Gastroenterology LLP | | 2018 |
| London One Health Ltd | Professional & scientific | 2023 |
| London Retreat Country Park Limited | Real estate | 2025 |
| London Rock Tours Limited | Administrative & support | 2012 |
| London Temporary Services Limited | Construction | 2022 |
| London Town Plumbing Limited | Construction | 2025 |
| London Transport Flying Training Ltd | Information & communication | 2014 |
| Lone Star Management Services LLP | | 2006 |
| Longevous Ltd | Wholesale & retail | 2024 |
| Lost Valley Camping Limited | Hospitality | 2008 |
| Lothbrok UK Ltd | Construction | 2017 |
| Lots 2 Sell Ltd | Wholesale & retail | 2023 |
| Loughborough Road Investments Limited | Financial services | 1969 |
| Loula Designs Limited | Wholesale & retail | 2023 |
| Love Craft and Tea Ltd | Wholesale & retail | 2023 |
| Love Millions Limited | Professional & scientific | 2019 |
| Lovelace Consulting Limited | Information & communication | 2005 |
| LOW Carbon Innovation Fund 2 LP | | 2019 |
| LOW Carbon Innovation Fund 2-B LP | | 2021 |
| Loxain Limited | Wholesale & retail | 2026 |
| LS Europe Limited | Wholesale & retail | 2016 |
| LSC Properties Ltd | Construction | 2025 |
| Luceo London Ltd | Wholesale & retail | 2026 |
| Lucidplan Limited | Professional & scientific | 2022 |
| Lucky 7 Lighting Limited | Administrative & support | 2015 |
| Lumen and Line Ltd | Professional & scientific | 2026 |
| Lumina Health Limited | Health & social care | 2021 |
| Luminar Developments Surrey Limited | Construction | 2016 |
| Luna Tanning Weybridge Ltd | Other services | 2021 |
| Lusso New Homes (Caversham) LLP | | 2025 |
| Luvieh Jewelry Ltd | Wholesale & retail | 2020 |
| LUX Global Solutions Ltd | Professional & scientific | 2018 |
| Luxcn International Limited | Education | 2011 |
| Luxton Collective Limited | Hospitality | 2025 |
| LVT Distribution Ltd | Wholesale & retail | 2024 |
| LY Development Limited | Construction | 2022 |
| Lydia Created Ltd | Arts & recreation | 2014 |
| Lyelands Estates Limited | Hospitality | 2021 |
| Lyndsey Ellis Design Ltd | Professional & scientific | 2018 |
| Lynsouth Developments Limited | Real estate | 1986 |
| Lynx Golf Limited | Wholesale & retail | 2012 |
| M & C Hair and Beauty Limited | Other services | 2018 |
| M & J Cleaning Limited | Administrative & support | 2017 |
| M & M Estates (UK) Limited | Construction | 2003 |
| M E Gale Transport Solutions Ltd | Wholesale & retail | 2021 |
| M F Technicals Limited | Wholesale & retail | 2018 |
| M Good Systems Limited | Professional & scientific | 2006 |
| M J S Estates Ltd | Real estate | 2010 |
| M Stone Property Solutions Limited | Real estate | 2012 |
| M&C Surrey Limited | Construction | 2025 |
| M&C Ventures Ltd | Real estate | 2024 |
| M&Mm Ltd | Real estate | 2021 |
| M&S Design & Construction Ltd | Real estate | 2023 |
| M. C. Hersey & SON Ltd | Manufacturing | 1997 |
| Mabl Consulting Ltd | Professional & scientific | 2022 |
| MAC4 Properties Ltd | Real estate | 2015 |
| Macdonald Design Studio Ltd | Administrative & support | 2026 |
| Macdonald's Farm Hospitality Limited | Wholesale & retail | 2021 |
| Macgregor Consultants Limited | Professional & scientific | 1998 |
| Macgregor Life Sciences Consulting Ltd | Professional & scientific | 2025 |
| Macgregor One Limited | Real estate | 2016 |
| Mach 1 (Surrey) Limited | Wholesale & retail | 2004 |
| Mackenzie Steel Holdings Limited | Professional & scientific | 2012 |
| Maclinica Ltd | Health & social care | 2024 |
| Macro Projects Limited | Professional & scientific | 2018 |
| Macz Management Ltd | Construction | 2019 |
| Made Simple Finance Limited | Administrative & support | 2020 |
| Madsen Consulting Ltd | Administrative & support | 2016 |
| Magellan Financing & Development Limited | Administrative & support | 2018 |
| Maggie Swain Events Ltd | Other services | 2015 |
| Magna Asset Management (West Byfleet) Limited | Construction | 2015 |
| Magnani Pharma Consulting Limited | Professional & scientific | 2014 |
| Magnima Ltd | Professional & scientific | 2017 |
| Major Event Organisers Association | Other services | 2016 |
| Make a Bigger Difference Ltd | Professional & scientific | 2019 |
| Malak Property Management Limited | Real estate | 2016 |