| Lane 4 Swim Limited | Education | 2021 |
| Langhedge Holdings Limited | Other services | 2008 |
| Langley Climate Control Ltd | Construction | 2014 |
| Langley Point Property Management Company Limited | Households | 2021 |
| Langley Services Group Ltd | Construction | 2020 |
| Lanterns (Gresley Way) Management Company Limited | Real estate | 2018 |
| Lanza Roofing Ltd | Construction | 2025 |
| Lara Louise Aesthetics Ltd | Other services | 2025 |
| Larches Residents Association Limited(The) | Households | 1968 |
| Laredo Tech Ltd | Information & communication | 2021 |
| Largess Investment Limited | Information & communication | 2025 |
| Lari Consulting Limited | Professional & scientific | 2012 |
| Lari Estates Ltd | Real estate | 2017 |
| Larkshall Investments Limited | Real estate | 2000 |
| LAS Tax Management Limited | Professional & scientific | 1992 |
| Laser CNC Ltd | Manufacturing | 2019 |
| Laser Survey Services Limited | Professional & scientific | 2021 |
| Laser TAG Harlow Ltd | Education | 2021 |
| Last Adam Engineering Ltd | Professional & scientific | 2022 |
| Latch Engineering Limited | Professional & scientific | 2014 |
| Lathams Yard Hackney Residents Management Company Limited | Households | 2007 |
| Latona Limited | Arts & recreation | 2019 |
| Latten Building Projects Limited | Construction | 1979 |
| Latton Green Services Ltd | Construction | 2017 |
| Latton Property Group Limited | Real estate | 2025 |
| Lattyhouse Ltd | Construction | 2025 |
| Laudamac Ltd | Construction | 2020 |
| Laura-Anne Consulting Ltd | Professional & scientific | 2023 |
| Laurel Grove Management Company (Uttoxeter) Limited | Households | 2011 |
| Laurels Residents Association (Buckhurst Hill) Limited(The) | Professional & scientific | 1984 |
| Lavender Fields (Hitchin) Management Company Limited | Households | 2005 |
| Lavendulan Limited | Real estate | 2021 |
| Law & Chiriac Advisory Group Limited | Professional & scientific | 2025 |
| Law Finance Services Limited | Professional & scientific | 2014 |
| Lawsmith Legal Practice Ltd | Professional & scientific | 2016 |
| Lawson Heating Ltd | Construction | 2017 |
| Lawws Ltd | Hospitality | 2025 |
| Layrek Properties Ltd | Real estate | 2021 |
| Lazer Lamps Employees' Trustees Limited | Administrative & support | 2022 |
| Lazer Lamps Ltd | Manufacturing | 2010 |
| LB Art Holdings Limited | Financial services | 2023 |
| LB Invest Group Limited | Administrative & support | 2025 |
| LC Aviation Services Ltd | Transport & logistics | 2023 |
| LD1 Limited | Construction | 2019 |
| LD5 Ltd | Construction | 2017 |
| LDH Network Solutions Ltd | Information & communication | 2025 |
| LDN Bunker Ltd | Hospitality | 2024 |
| LDN East Ltd | Hospitality | 2022 |
| LDN Riverside Ltd | Hospitality | 2020 |
| LDN Selective Limited | Information & communication | 2014 |
| LDN Wild Ltd | Hospitality | 2023 |
| LE BON Dieu Limited | Information & communication | 2019 |
| LE COQ ROI Limited | Hospitality | 2021 |
| LE Manoir DE LA Haule Limited | Real estate | 2000 |
| LE Treda Ltd | Professional & scientific | 2022 |
| Leader Express (UK) Limited | Construction | 2022 |
| Leading Tapers Finishers Limited | Construction | 2023 |
| Leadway Konsulting Services Ltd | Health & social care | 2012 |
| Leafield Consulting Limited | Information & communication | 1998 |
| Leaftax Ltd | Transport & logistics | 2018 |
| Leaside Leisure Limited | Construction | 1993 |
| Leat Consultants Ltd | Information & communication | 2026 |
| Leben & Mehr Holdings Ltd | Financial services | 2025 |
| Ledd Ltd | Professional & scientific | 2025 |
| Ledger Scaffolding London Limited | Construction | 2022 |
| LEE Adams Carpentry & Construction Limited | Construction | 2016 |
| LEE Game Prestige Ltd | Wholesale & retail | 2021 |
| LEE James Simmons Ltd | Arts & recreation | 2015 |
| LEE Valley Cycles Limited | Wholesale & retail | 2012 |
| LEE Valley Fruit & VEG Limited | Wholesale & retail | 2021 |
| Legacy Box International Limited | Information & communication | 2025 |
| Legalis Chambers Ltd | Professional & scientific | 2025 |
| Legendra Ltd | Wholesale & retail | 2025 |
| Legist Realty Limited | Real estate | 2020 |
| Lehope Care Limited | Health & social care | 2015 |
| Lehope Professionals Limited | Administrative & support | 2024 |
| Leigh Design and Build Ltd | Construction | 2019 |
| Leighton Grange Management Limited | Households | 1989 |
| Leitz Tooling UK Limited | Manufacturing | 1907 |
| Leksum Ltd | Real estate | 2025 |
| Lemon Tree Project CIC | Public administration | 2024 |
| Lenomichaels Ltd | Health & social care | 2023 |
| Lenscop Media Ltd | Information & communication | 2019 |
| Leo's Transport Ltd | Transport & logistics | 2025 |
| Leonard Brooks (Harlow) Limited | Wholesale & retail | 1981 |
| Leonard Global Ltd | Professional & scientific | 2018 |
| Leone Lettings Ltd | Real estate | 2024 |
| Leorex Limited | Financial services | 2026 |
| Leos Engineering Limited | Construction | 2025 |
| Leozar Limited | Financial services | 2025 |
| Lerosch Limited | Health & social care | 2024 |
| LES Points Cardinaux Limited | Real estate | 2025 |
| Lesstreso Coffee UK Ltd | Manufacturing | 2026 |
| Letcombe Gardens (Grove) Management Company Limited | Households | 2018 |
| Letoseven Limited | Arts & recreation | 2013 |
| Lettygo Land Ltd | Information & communication | 2020 |
| Levent Properties Ltd | Real estate | 2018 |
| Lever House (Bolton) RTM Company Ltd | Households | 2013 |
| Levrion Consulting Limited | Information & communication | 2024 |
| Lewis Elec Ltd | Construction | 2026 |