| Launchpad Publishing Limited | Information & communication | 2015 |
| Laura Knapp Limited | Administrative & support | 2019 |
| Laurelgrove Productions Limited | Information & communication | 2007 |
| Lauria U.K Ltd | Hospitality | 2025 |
| Laurian Consultancy Limited | Arts & recreation | 2007 |
| Law-Hire Ltd | Administrative & support | 2024 |
| Lazy Digs Limited | Real estate | 2021 |
| Lazy Dog Ltd | Extraterritorial | 2019 |
| Lazy Dough Ltd | Hospitality | 2021 |
| LE DUC Limited | Hospitality | 2024 |
| Leadgenplus+ Limited | Information & communication | 2011 |
| Leading in Risk Ltd | Professional & scientific | 2026 |
| Leading With Grace Ltd | Other services | 2024 |
| Leadingdog Limited | Wholesale & retail | 2018 |
| Leadmax Limited | Information & communication | 2025 |
| Learning Direct Ltd | Education | 2012 |
| Leasowes Holding Company Limited | Financial services | 2020 |
| Leelafy Limited | Professional & scientific | 2025 |
| Leelafy LP | | 2025 |
| Lemuel Company Limited | Transport & logistics | 2016 |
| LEO Consult Limited | Real estate | 1986 |
| LEO Trippi (UK) Limited | Administrative & support | 2011 |
| Leonora Birts Interior Design Ltd | Administrative & support | 2013 |
| Less Stress Ltd | Information & communication | 2001 |
| Let's Play Music Ltd | Education | 2014 |
| Levamiri Limited | Real estate | 2024 |
| Lewington Wealth Management Limited | Financial services | 2001 |
| Lewis Roofing Ltd | Construction | 2026 |
| Lexconex Limited | Professional & scientific | 2007 |
| Lexington Associates Limited | Financial services | 2020 |
| Lexington Wealth Management Limited | Financial services | 2005 |
| Lexpars Limited | Information & communication | 2023 |
| LI RA Cafe Ltd | Hospitality | 2025 |
| LIC Group Ltd | Financial services | 2023 |
| Licatas Limited | Other services | 2008 |
| Licium Limited | Professional & scientific | 2023 |
| Lifegarb Ltd | Wholesale & retail | 2016 |
| Lifestyle Safety Limited | Administrative & support | 2017 |
| Light Fish Ltd | Hospitality | 2021 |
| Light Sport Limited | Professional & scientific | 2024 |
| Lighthouse (Yoga and Investments) Ltd | Extraterritorial | 2015 |
| Lightleaf LLP | | 2024 |
| Linden House Financial Services Limited | Financial services | 1994 |
| Line One Distributors Limited | Wholesale & retail | 1997 |
| Lins Entech Limited | Wholesale & retail | 2023 |
| Liquid Internet Limited | Information & communication | 1999 |
| Lisoro Design Ltd | Wholesale & retail | 2021 |
| Little Flowers Care | Education | 2024 |
| Little Meadow Management Company Limited | Households | 2004 |
| LIU Estates Limited | Real estate | 2025 |
| LIV and LET Dough Pizza Co Ltd | Hospitality | 2026 |
| LIV01 Ltd | Information & communication | 2024 |
| Livet Limited | Real estate | 2019 |
| Lloyd Price Properties Ltd | Real estate | 2017 |
| Lloyds Estimating Ltd | Professional & scientific | 2025 |
| LMC Window Cleaning Ltd | Administrative & support | 2021 |
| LME Cleaning Services Limited | Administrative & support | 2008 |
| LME Villas Limited | Extraterritorial | 2007 |
| Local Compass Ltd | Administrative & support | 2024 |
| Lockhart & Lockhart Limited | Professional & scientific | 2022 |
| Lodg.Ic Ltd | Administrative & support | 1954 |
| Lodge Clean Co Ltd | Administrative & support | 2025 |
| Lodge Security Limited | Administrative & support | 2006 |
| Lodge Service (Eastern) Limited | Administrative & support | 1961 |
| Lodge Service (Western) Limited | Administrative & support | 1958 |
| Lodge Service Intelligence Limited | Administrative & support | 2009 |
| Lodge Service International Limited | Professional & scientific | 1961 |
| Lodge Service Technical Limited | Other services | 1988 |
| Lodge Service UK Limited | Administrative & support | 1954 |
| Lofrix Technologies Distribution Limited | Professional & scientific | 2017 |
| Logicmelon Media Limited | Professional & scientific | 2019 |
| Logistics Partner Limited | Transport & logistics | 2017 |
| Lola UK Limited | Wholesale & retail | 2009 |
| London Business Coaching Ltd | Professional & scientific | 2015 |
| London Woodwork Company Limited | Construction | 2025 |
| Longa Ltd | Professional & scientific | 2022 |
| Longbow Group Ltd | Construction | 2017 |
| Longford Property Partnership Limited | Real estate | 2003 |
| LOOP1 International Limited | Information & communication | 2017 |
| LOOP1 UK Limited | Information & communication | 1991 |
| Lord Barber Shop Ltd | Other services | 2016 |
| Lord Barber Shop RWB Ltd | Other services | 2019 |
| Lord Barber Shop Tetbury Ltd | Other services | 2019 |
| Lost Car Key Specialist Limited | Wholesale & retail | 2019 |
| Lost in Cult Ltd | Wholesale & retail | 2021 |
| Lost in Cult Records Ltd | Wholesale & retail | 2023 |
| Louise Parry Jewellery Design Limited | Manufacturing | 2006 |
| Lounge Design Ltd | Administrative & support | 2008 |
| Loveday Mews Management Company Limited | Health & social care | 2017 |
| Lovelocks Polo Stud Ltd | Agriculture & fishing | 2011 |
| Lovettswood Farm Limited | Agriculture & fishing | 2007 |
| LOW Carbon Tidal Limited | | 2011 |
| Lower Burytown Farms Limited | Agriculture & fishing | 1980 |
| Lower Mill Estate Holidays Limited | Real estate | 2000 |
| Lowther Interiors Ltd | Construction | 2025 |
| LPC International Ltd | Information & communication | 1996 |
| Lpci Ltd | Administrative & support | 2007 |
| LPS Electrical Contractors Limited | Construction | 2012 |
| LS Aviation Services Limited | Professional & scientific | 2026 |
| LT Plumbing & Property Maintenance Ltd | Administrative & support | 2009 |