| LE Mesurier's Ltd | Administrative & support | 2008 |
| Leadmaster UK Limited | Construction | 2008 |
| League Against Cruel Sports (UK) Limited | Other services | 1993 |
| Leak Locators Limited | Professional & scientific | 2000 |
| Leap Mobility Limited | Information & communication | 2025 |
| Learning Resources Limited | Wholesale & retail | 1994 |
| Lebanon Property Trust (1936) | Construction | 1936 |
| LEE & KIM Ltd | Hospitality | 2024 |
| Legal-Professional Limited | Financial services | 1997 |
| Legato Design Ltd | Professional & scientific | 2025 |
| Lennox Estates (Hampton Wick) Limited | Construction | 2017 |
| Lennox Estates (Liston) Limited | Construction | 2016 |
| Lennox Estates (New Court) Limited | Construction | 2016 |
| Lennox Estates Limited | Financial services | 2015 |
| Leonard Law LLP | | 2011 |
| Lesslands Property Services Ltd | Households | 2025 |
| Lethe Assisted Living Limited | Financial services | 2020 |
| Letticia Stiles Ltd | Arts & recreation | 2017 |
| Level Change Performance Coaching Ltd | Professional & scientific | 2024 |
| Levelupp Ltd | Administrative & support | 2021 |
| Lewis Electrical Distributors Ltd | Wholesale & retail | 2020 |
| Lewtam Limited | Construction | 2017 |
| Leybourne Securities Limited | Financial services | 1985 |
| LF Roofing and Driveways Limited | Construction | 2025 |
| LFH Commercial Ltd | Professional & scientific | 2025 |
| Liam Sullivan Video Production Limited | Professional & scientific | 2024 |
| Liberado Limited | Professional & scientific | 2019 |
| Liberty Street Residents Association Ltd | Households | 1998 |
| Librii Limited | Manufacturing | 1990 |
| Lidia Nistor Limited | Professional & scientific | 2017 |
| Life Homes Ltd | Real estate | 2017 |
| Lifelong Mobility Ltd | Education | 2024 |
| Light Stylist Ltd | Manufacturing | 2021 |
| LIL Gymnasts Ltd | Arts & recreation | 2015 |
| Lime PR Consultants LLP | | 2017 |
| Limelight Portrait Studios Ltd | Professional & scientific | 2011 |
| Linguaid Consultancy Ltd | Professional & scientific | 2006 |
| Links Law Limited | Professional & scientific | 2022 |
| Lions Gate Freehold Ltd | Administrative & support | 2013 |
| Liquid Gold Detailing Ltd | Administrative & support | 2018 |
| Liquid Sports Ltd | Wholesale & retail | 2011 |
| Lisa Hatswell Consultancy Limited | Extraterritorial | 2011 |
| Lisa PAN Ltd | Hospitality | 2022 |
| List Whisperer Ltd | Administrative & support | 2019 |
| Listavia International Consultants Limited | Professional & scientific | 1990 |
| Litaa Limited | Information & communication | 2011 |
| Little Rays Daycare Ltd | Health & social care | 2023 |
| Littlebrook Limited | Real estate | 1978 |
| Livesey Aviation Consultants Limited | Education | 2007 |
| LJI Limited | Administrative & support | 2025 |
| LJP Appliances Limited | Manufacturing | 2014 |
| LLC Partnership Ltd | Construction | 2023 |
| Lloyd George Archive Limited | Professional & scientific | 2003 |
| LM Stallions Ltd | Agriculture & fishing | 2020 |
| LMA Advisors Limited | Professional & scientific | 2024 |
| Lockford Ltd | Construction | 2025 |
| Locologic Limited | Information & communication | 1997 |
| Logi Food Technologies Ltd | Manufacturing | 2017 |
| Logos Therapy Services Limited | Health & social care | 2003 |
| London Crew Pro Ltd | Wholesale & retail | 2025 |
| London Duck Tours Limited | Administrative & support | 2017 |
| London Office Solutions Group Ltd | Professional & scientific | 2019 |
| London Squash Limited | Arts & recreation | 2023 |
| London Tennis Coaching Ltd | Education | 2024 |
| London Theatre Company (Group Holdings) Limited | Arts & recreation | 2026 |
| Longdene Homecare Limited | Health & social care | 2010 |
| Lore&Layout Ltd | Information & communication | 2026 |
| Lorono Limited | Real estate | 2002 |
| Lotus Financial Services Ltd | Professional & scientific | 2016 |
| Loxhill Livery Limited | Other services | 2019 |
| LP Global Holdings Limited | Professional & scientific | 2021 |
| LR4X4.COM Limited | Other services | 2011 |
| Lucas Accounting Limited | Professional & scientific | 2014 |
| Lucas Groundworks Limited | Construction | 1999 |
| Lucy Readings Communications Limited | Professional & scientific | 2014 |
| Lumina Analytics Ltd | Information & communication | 2025 |
| Luxsec Ltd | Information & communication | 2019 |
| Luxury Gourmet Ltd | Hospitality | 2018 |
| Lynne Dyer Ltd | Real estate | 2021 |
| Lynne Hargreaves Associates Limited | Administrative & support | 2003 |
| Lysander Associates Limited | Construction | 2001 |
| Lysander Group Limited | Construction | 2022 |
| Lyte Works Ltd | Professional & scientific | 2026 |
| LZT Investments Limited | Administrative & support | 2018 |
| M a Spice Ltd | Hospitality | 2019 |
| M Jolly Properties Limited | Real estate | 2020 |
| M R Business Ltd | Transport & logistics | 2024 |
| M&R Security Services Limited | Administrative & support | 2020 |
| M-United Limited | Wholesale & retail | 2021 |
| M.A.B. Trustee Company Limited | Financial services | 1981 |
| M.J. Coleman & Sons Ltd | Construction | 2002 |
| M.J. Goater Building Services Ltd | Construction | 2011 |
| M.J.Coleman & Sons Roofing Consultants Ltd | Construction | 2017 |
| M3 Asbestos Limited | Administrative & support | 2012 |
| M3 Asbestos Surveys Limited | Construction | 2014 |
| M3 Marine Limited | Construction | 2014 |
| Mabel and Badger Ltd | Wholesale & retail | 2024 |
| MAC Family Properties Limited | Real estate | 2016 |
| Macdonagh Wright Ltd | Administrative & support | 2013 |
| Madagile Ltd | Information & communication | 2014 |