| Lasart Limited | Wholesale & retail | 2021 |
| Laser Hounslow Franchisees Ltd | Health & social care | 2021 |
| Latafat Limited | Professional & scientific | 2019 |
| Latestlifestyle Limited | Extraterritorial | 2008 |
| Latthar Consultancy Ltd | Education | 2022 |
| Lavender Big Band Ltd | Arts & recreation | 2026 |
| Law Costs Consultancy (1976) Limited | Professional & scientific | 2016 |
| Layni Beauty Ltd | Other services | 2025 |
| Lbpc Ltd | Wholesale & retail | 2019 |
| LBX Enterprises Ltd | Construction | 2021 |
| LCM Tech Ltd | Information & communication | 2019 |
| Ldshair Ltd | Other services | 2019 |
| Ldst Limited | Other services | 2023 |
| Leads Factory Limited | Professional & scientific | 2015 |
| League of Sound Limited | Information & communication | 2015 |
| Leapora Ltd | Hospitality | 2025 |
| Lease-A-Place UK Ltd | Real estate | 2024 |
| Leather Origin Ltd | Wholesale & retail | 2022 |
| Legacy Family Real Estate Limited | Real estate | 2025 |
| Lemongrove Productions Ltd | Information & communication | 2009 |
| LEN Developments Limited | Construction | 2012 |
| Lentuja Ltd | Wholesale & retail | 2025 |
| LEO UK Security Ltd | Construction | 2018 |
| LES Artisanes Limited | Manufacturing | 2004 |
| Lets DO Business Limited | Real estate | 2003 |
| LETTINGS4ALL Ltd | Wholesale & retail | 2025 |
| Lever Bookkeeping Limited | Professional & scientific | 2013 |
| Lever Bros & Co Limited | Administrative & support | 2005 |
| Lever Payroll Limited | Administrative & support | 2013 |
| LEX MAX Property Investments (GB) Ltd | Other services | 2010 |
| Lexmart Limited | Information & communication | 2023 |
| Lexstruct Ltd | Construction | 2024 |
| Lfdelta UK Ltd | Construction | 2019 |
| Lfegan Limited | Professional & scientific | 2013 |
| Libertas Capital Group Ltd | Real estate | 2025 |
| Libraa Consumers Foods Limited | Wholesale & retail | 2025 |
| Licensepal Limited | Wholesale & retail | 2010 |
| Life Begins at Nifty Ltd | Administrative & support | 2016 |
| Lifeism Limited | Education | 2021 |
| Lightfoot Investments Ltd | Real estate | 2023 |
| Lightfoot Property Developments Limited | Real estate | 2025 |
| Lightwave Labs Ltd | Administrative & support | 2022 |
| Lilac and Bloom Floristry Ltd | Wholesale & retail | 2022 |
| LIM Jones Limited | Extraterritorial | 2022 |
| Limo Chauffeurs Ltd | Transport & logistics | 2012 |
| Linear Tools Limited | Wholesale & retail | 1977 |
| Lion Court and Swan Court RTM Company Limited | Households | 2025 |
| Lion Wharf Management Limited | Real estate | 2015 |
| Lions of Abbas Ltd | Construction | 2023 |
| Liquid Quant Limited | Information & communication | 2026 |
| Lister Electrics Ltd | Construction | 2025 |
| Lita Solutions Ltd | Construction | 2021 |
| Little Chefs Academy Ltd | Education | 2023 |
| Little Crumpets Limited | Health & social care | 2018 |
| Little DEW Publications Ltd | Information & communication | 2023 |
| Little Eagles Childcare Ltd | Health & social care | 2023 |
| Little Gaia Limited | Health & social care | 2025 |
| Little Jazz Stars Ltd | Arts & recreation | 2026 |
| Little Larrikins Ltd | Administrative & support | 2018 |
| Little Warkworth House (Isleworth) Management Company Limited | Households | 1989 |
| Live Life UN Limited | Information & communication | 2019 |
| Living Abroad Advisory Centres Limited | Other services | 2005 |
| Living to Create Magic Ltd | Arts & recreation | 2024 |
| Liviu Building Ltd | Construction | 2022 |
| Lizard Beauty Ltd | Wholesale & retail | 2023 |
| Ljp-Learning Ltd | Professional & scientific | 2014 |
| LNA Ltd | Information & communication | 2013 |
| Lnnym Ltd | Transport & logistics | 2023 |
| Local Solicitors Ltd | Professional & scientific | 2017 |
| Loft Bite Limited | Wholesale & retail | 2025 |
| Lofts 4 U Limited | Construction | 2003 |
| Logar Handyman Driver Ltd | Other services | 2022 |
| Logic Accountants Ltd | Professional & scientific | 2023 |
| Logistics Skills Alliance Limited | Education | 2013 |
| Logo-It Sportswear Ltd | Manufacturing | 2023 |
| Lola & Lola Limited | Manufacturing | 2018 |
| Lonago Limited | Professional & scientific | 2023 |
| London & Surrey Health Limited | Health & social care | 2017 |
| London Aesthetics Academy Limited | Education | 2011 |
| London Aggregates Haulage Ltd | Wholesale & retail | 2023 |
| London Beats & Festivals Limited | Hospitality | 2023 |
| London Borough of Hounslow Chamber of Commerce Limited | Administrative & support | 2020 |
| London Business Support Services Limited | Wholesale & retail | 2026 |
| London Convenient Tour LCT Ltd | Administrative & support | 2024 |
| London Endocrine and Diabetes Clinic Ltd | Health & social care | 2022 |
| London Japanese Interpreter Limited | Professional & scientific | 2021 |
| London Medweb Limited | Professional & scientific | 2015 |
| London Neuro Physio Ltd | Health & social care | 2012 |
| London Nexus Consultancy Ltd | Professional & scientific | 2024 |
| London Nutritional Advisory Limited | Health & social care | 2017 |
| London Plus Limited | Hospitality | 2014 |
| London Riverside Limited | Real estate | 2025 |
| London Road Isleworth Property Company Limited | Real estate | 2009 |
| London Shawarma Ltd | Wholesale & retail | 2025 |
| London West Cleaning Ltd | Administrative & support | 2023 |
| Londondanceco Productions Limited | Arts & recreation | 2019 |
| Long Distances 24/7 Limited | Transport & logistics | 2019 |
| Long Lane Films Ltd | Information & communication | 2025 |
| Lookbook Group Ltd | Wholesale & retail | 2026 |
| Lookin' Glass Ltd | Manufacturing | 2021 |