| Krrish Ventures Limited | Real estate | 2022 |
| KSG Comfort Ltd | Construction | 2020 |
| KST Building Services Ltd | Construction | 2015 |
| KU Ventures Ltd | Real estate | 2019 |
| Kuch Mazedaar SI Batain Limited | Information & communication | 2025 |
| KVD Homes Ltd | Real estate | 2016 |
| Kwalcast Floor Hire Limited | Construction | 2018 |
| L & E Property Services Limited | Other services | 2015 |
| L a Contracts Ltd | Construction | 2019 |
| L B Facilities Contractors Limited | Administrative & support | 2020 |
| L N Glazing Ltd | Construction | 2018 |
| L&T Homes Ltd | Real estate | 2022 |
| L&W Service R&M Ltd | Construction | 2022 |
| L.T.J. Limited | Professional & scientific | 2004 |
| LA LA Lashes Limited | Other services | 2009 |
| LA1 Properties Limited | Real estate | 2017 |
| Label Bespoke Limited | Manufacturing | 2015 |
| Laderman & Co Limited | Administrative & support | 2003 |
| Ladhar Properties Ltd | Real estate | 2025 |
| Ladus Ltd | Construction | 2025 |
| Ladysmith Building Ltd | Real estate | 2025 |
| Lakeshore Properties Limited | Real estate | 2015 |
| Lakeside Imports Limited | Wholesale & retail | 2016 |
| Lal-It Limited | Information & communication | 2014 |
| Lambond Limited | Construction | 1988 |
| Lamont Studios Ltd | Information & communication | 2007 |
| Lanagrade Limited | Administrative & support | 1996 |
| Lancelot Management Limited | Administrative & support | 1997 |
| Landas Care Homes Ltd | Health & social care | 2023 |
| Landas Care Services Ltd | Health & social care | 2023 |
| Landco Limited | Real estate | 1984 |
| Landmark Property Consultancy Ltd | Construction | 2023 |
| Landmark Recruitment Services Limited | Administrative & support | 2020 |
| Landseer Stifford Limited | Construction | 2014 |
| Langham Design Ltd | Wholesale & retail | 2026 |
| Langham Mansions Properties Limited | Real estate | 1986 |
| Langston Greenway Ltd | Administrative & support | 2021 |
| Langton Quality Foods Limited | Hospitality | 2010 |
| Language Linker Limited | Other services | 2004 |
| Language Recruitment Services Holdings Limited | Administrative & support | 2004 |
| Lani Investments Limited | Real estate | 2019 |
| Lara Upminster Ltd | Hospitality | 2025 |
| Larisa MED Limited | Professional & scientific | 2024 |
| Larner Recycling Ltd | Water & waste | 2010 |
| Larr Lets Ltd. | Real estate | 2024 |
| Lash Bar Limited | Wholesale & retail | 2005 |
| Lash Perfect Limited | Professional & scientific | 2006 |
| Lasku Nova Properties Ltd | Real estate | 2025 |
| Lastzone Limited | Construction | 2001 |
| Latonis Technologies Limited | Information & communication | 2025 |
| Laugh OUT Loud Ltd | Education | 2024 |
| Lauriston Saggar LLP | | 2014 |
| Lavish One Limited | Real estate | 2016 |
| Law Support Limited | Administrative & support | 2003 |
| Lawford Legal Limited | Professional & scientific | 2025 |
| Lawology Ltd | Information & communication | 2025 |
| Lawyer Talent Network Limited | Administrative & support | 2018 |
| Laza Plumbing & Heating Merchants Limited | Wholesale & retail | 2011 |
| Lazania Tandori Restaurant & Bar Limited | Hospitality | 2013 |
| Lazer Living Limited | Real estate | 2024 |
| Lbdr Limited | Professional & scientific | 2021 |
| LBM Construction North London Limited | Construction | 2016 |
| LBT Flooring Limited | Construction | 1996 |
| LCA Property Services Ltd | Construction | 2016 |
| LCM Trading Ltd | Manufacturing | 2023 |
| LD Nails and Spa Limited | Other services | 2019 |
| Leadsclick Ltd | Information & communication | 2014 |
| LEARN2MASTIC Ltd | Information & communication | 2026 |
| LEE & Khaw Ltd | Manufacturing | 2016 |
| LEE Software Limited | Information & communication | 2025 |
| Lee's Services Limited | Administrative & support | 2017 |
| Leftside Creative Ltd | Other services | 2021 |
| Legacy Club Ltd | Other services | 2020 |
| Legalet Limited | Real estate | 2001 |
| Leisure Float Limited | Health & social care | 2000 |
| LEJ Partnerships Ltd | Professional & scientific | 2026 |
| Lellow Properties Limited | Administrative & support | 2015 |
| Lennon Construction & Development Co Ltd | Construction | 2024 |
| Lennon Consultancy Limited | Professional & scientific | 2018 |
| Leo&Nora Hair Ltd | Wholesale & retail | 2026 |
| Leodev Limited | Households | 2021 |
| Leoliving Ltd | Wholesale & retail | 2021 |
| Leonardo Investments Limited | Construction | 2008 |
| Lestrem Spinney (Fyfield) Limited | Agriculture & fishing | 2017 |
| Let's Go Potty Limited | Arts & recreation | 2020 |
| Let's Sanitise Limited | Wholesale & retail | 2020 |
| Let's Think Forum | Education | 2011 |
| Levelix Ltd | Construction | 2026 |
| Levenson Properties Limited | Real estate | 1950 |
| Leviathan Wealth Limited | Wholesale & retail | 2013 |
| Lewis & Scott Community Housing Limited | Real estate | 2024 |
| Lewis & Scott Group Ltd | Financial services | 2022 |
| Lewis & Scott Homes Limited | Construction | 2024 |
| Lewis & Scott Homes Woodrolfe Ltd | Construction | 2024 |
| Lewis & Scott Retirement Living Halstead Ltd | Construction | 2022 |
| Lewis & Scott Retirement Living Ltd | Construction | 2020 |
| Lewis & Scott Retirement Living Tollesbury Ltd | Construction | 2022 |
| Leychi Ltd | Transport & logistics | 2020 |
| Leytonstone Investments Limited | Real estate | 2024 |
| Leytonstone Ventures Limited | Real estate | 2024 |