| LEO Midco Limited | Financial services | 2025 |
| LEO Topco Limited | Financial services | 2025 |
| Lesley Stuart Ltd | Administrative & support | 2023 |
| Leslie Brown Limited | Manufacturing | 1958 |
| Leslie Easton & Co. Limited | Construction | 1987 |
| Leslie Faizi Limited | Administrative & support | 2012 |
| Lesnes Properties Limited | Real estate | 2019 |
| Lesterose Holdings Limited | Financial services | 2005 |
| Lesterose Northern Holdings Limited | Financial services | 2023 |
| Lesterose Northern Limited | Financial services | 2023 |
| Lesterose Scotland Limited | Construction | 1996 |
| Letterbox Treats Limited | Wholesale & retail | 2020 |
| Level UP Gaming BUS Limited | Arts & recreation | 2021 |
| Levelquinn Investments Limited | Real estate | 2019 |
| Lewis & Co Homes Ltd | Real estate | 2023 |
| Lewis PM Ltd | Hospitality | 2026 |
| Lewis Property Holdings (Kent) Ltd | Real estate | 2025 |
| Lexford Ltd | Administrative & support | 2009 |
| Lezbbq Ltd | Hospitality | 2022 |
| Lfted Ltd | Households | 2026 |
| LI Building and Construction Limited | Construction | 2021 |
| Lief Ltd | Administrative & support | 2013 |
| Life Changing Digital Limited | Education | 2023 |
| Life Changing Tuition Limited | Education | 2015 |
| Life Pilot Limited | Health & social care | 2016 |
| Life Safety Fire Systems Limited | Construction | 2026 |
| Lift Doctor 24/7 Limited | Professional & scientific | 2016 |
| Lift Modernisation Ltd | Construction | 2025 |
| Lightbulb Productions Ltd | Information & communication | 2019 |
| Lighthouse Heritage Ltd | Information & communication | 2016 |
| Liiht Limited | Administrative & support | 2017 |
| Liledu UK Limited | Wholesale & retail | 2024 |
| Lilypops Property Limited | Real estate | 2019 |
| Lime Court (Freehold) Management Limited | Households | 2001 |
| Limestone Services (UK) Ltd | Extraterritorial | 2013 |
| Limetree Cleaning & Gardening Limited | Administrative & support | 2016 |
| Linao Holdings Limited | Professional & scientific | 2004 |
| Linbrook Limited | Real estate | 1998 |
| Linea Carpentry and Building Services Ltd | Construction | 2021 |
| Linear Building Services Limited | Administrative & support | 2010 |
| Lion (New Eltham) Limited | Professional & scientific | 2022 |
| Lion 59 Limited | Real estate | 2021 |
| Lionheart Change Management Limited | Administrative & support | 2013 |
| Lisa Jane Taylor Limited | Administrative & support | 2025 |
| Little Black Look Limited | Wholesale & retail | 2024 |
| Little Giggles Ltd | Health & social care | 2024 |
| Little Island Management Company Limited | Hospitality | 1993 |
| Little London Co Gifts Store Ltd | Wholesale & retail | 2021 |
| Little Orchard Holdings Limited | Financial services | 2022 |
| Little Sandwich Shopp Ltd | Hospitality | 2019 |
| LIV & FEI Ltd | Wholesale & retail | 2024 |
| Lizard Tech Solutions Limited | Wholesale & retail | 2015 |
| LJ Industries Ltd | Wholesale & retail | 2023 |
| Ljdm Cleaning Services Limited | Administrative & support | 2023 |
| Ljjfg Credit Management Limited | Professional & scientific | 2024 |
| LJM Building Services Sidcup Ltd | Construction | 2026 |
| LJW MEP Solutions Limited | Construction | 2019 |
| Ljwm Complex Ltd | Wholesale & retail | 2025 |
| LLC Contracts Ltd | Real estate | 2020 |
| LM Badminton Ltd | Arts & recreation | 2015 |
| LMC GAS Ltd | Construction | 2017 |
| LMC Rail Limited | Construction | 2020 |
| LMF Property Group Ltd | Wholesale & retail | 2024 |
| LMK Partnership Limited | Hospitality | 2020 |
| Lmnkt Ltd | Health & social care | 2022 |
| LMO Construction Ltd | Construction | 2017 |
| LMO Consultants Limited | Real estate | 2023 |
| LMO Group Freehold Holdings Ltd | Financial services | 2024 |
| LMO Group Holdings Ltd | Real estate | 2024 |
| LMO Property Investment Ltd | Real estate | 2017 |
| LMP Group Holdings Limited | Financial services | 2018 |
| LMP Installations (London) Limited | Professional & scientific | 1997 |
| LMP Installations Holdings Limited | Real estate | 2016 |
| LMP Installations Limited | Construction | 1997 |
| LN Dance Ltd | Arts & recreation | 2024 |
| LNS Trade UK Limited | Wholesale & retail | 2024 |
| Lobster Holdings Limited | Real estate | 2025 |
| Local Agent Group Lettings and Management Limited | Real estate | 2021 |
| Local Agent Group Limited | Real estate | 2019 |
| Local Transformation Services Limited | Real estate | 2010 |
| Lockdown Tech Ltd | Wholesale & retail | 2020 |
| Locks by Libs Limited | Other services | 2025 |
| Locksbottom Properties Limited | Real estate | 2017 |
| LOD Technical Services Limited | Construction | 2018 |
| Lodgeland Limited | Professional & scientific | 1989 |
| Lola & Friends Pet Care Limited | Other services | 2024 |
| Lolars Fabrics Ltd | Wholesale & retail | 2025 |
| Lollipops and Lipstick Limited | Other services | 2020 |
| Lollipops Limited | Health & social care | 2018 |
| London & Kent Scaffolding Services Ltd | Construction | 2022 |
| London Airports and VIP Cars Ltd | Administrative & support | 2016 |
| London and Country Homes (Clavering) Ltd | Construction | 2023 |
| London Chinese Language & Culture Centre Limited | Education | 2007 |
| London Cleaning Concierge Ltd | Administrative & support | 2017 |
| London Cooling Ltd | Energy | 2020 |
| London Elite Youth Ltd | Administrative & support | 2024 |
| London Footwear Limited | Wholesale & retail | 2025 |
| London Interior Solutions Limited | Construction | 2014 |
| London Key 1 Ltd | Real estate | 2014 |
| London Lifts (South East) Ltd | Manufacturing | 2024 |