| LEE Homes Limited | Households | 2015 |
| LEE Rutherford Commissioning Services Limited | Mining & quarrying | 2013 |
| Legacy NO.1 Limited | Construction | 2008 |
| Legal and Commercial Services Limited | Professional & scientific | 1984 |
| Legal Compliance and Risk Limited | Professional & scientific | 2016 |
| Lemiy Limited | Wholesale & retail | 2026 |
| Lemon Top Pictures Ltd | Information & communication | 2023 |
| Leo's Home-Made Sweets Limited | Professional & scientific | 1980 |
| Leonard Agricultural Engineering Services Ltd | Professional & scientific | 2019 |
| Lesrm Ltd | Hospitality | 2025 |
| Lester Marketing & Communications Ltd | Professional & scientific | 2021 |
| LET the Day Begin Ltd | Hospitality | 2025 |
| Let's Connect (ENG) Ltd | Health & social care | 2008 |
| Lets GET Moved Ltd | Transport & logistics | 2024 |
| Lets Play (Play Therapy for Children) Limited | Education | 2010 |
| Lets Pretend and Play C.I.C. | Education | 2021 |
| Lewis Quality Services Ltd | Professional & scientific | 2021 |
| LF Pathway Solutions Ltd | Health & social care | 2025 |
| LG Property Portfolio Ltd | Real estate | 2025 |
| Lgbt+ Housing UK Limited | Real estate | 2022 |
| Lgfr Limited | Professional & scientific | 2010 |
| Lgfr Properties Ltd | Construction | 2014 |
| LH Inspection Services Ltd | Professional & scientific | 2022 |
| LH Lettings Group Ltd | Real estate | 2025 |
| Lhap Property Group Ltd | Real estate | 2025 |
| Lhigham Limited | Construction | 2025 |
| LHL Properties Ltd | Real estate | 2019 |
| Liam Gate Digital Limited | Information & communication | 2023 |
| Lianjiang Kitchen UK Ltd | Hospitality | 2025 |
| Libannas Ltd | Other services | 2020 |
| Libertalia Press Ltd | Information & communication | 2025 |
| Liddle Engineering Limited | Professional & scientific | 2013 |
| Lido Enterprises Limited | Wholesale & retail | 2023 |
| Lightup TMC Ltd | Information & communication | 2024 |
| LIL Sprogs Limited | Wholesale & retail | 2025 |
| Lilley Stephen Ltd | Wholesale & retail | 2020 |
| Lily Kate Photography Ltd | Professional & scientific | 2022 |
| Lime Locum Limited | Professional & scientific | 2023 |
| Limetech Limited | Construction | 2022 |
| Lindsey Harrison Ltd | Real estate | 2020 |
| Lineage Homes Ltd | Real estate | 2025 |
| Lineage Investings Limited | Real estate | 2024 |
| Lineage Ledger Ltd | Financial services | 2025 |
| Lineagesolutions Ltd | Real estate | 2025 |
| Linear Shaped Limited | Professional & scientific | 2012 |
| Lingosaurs Ltd | Education | 2016 |
| Lingotot Teesside Limited | Education | 2015 |
| Linighan Construction Ltd | Construction | 2021 |
| Linxi Limited | Hospitality | 2023 |
| Litecom Semiconductors Limited | Extraterritorial | 2009 |
| Little Oaks Ingleby Ltd | Health & social care | 2018 |
| Little People Day Nursery Ltd | Arts & recreation | 1994 |
| Little Rays of Sunshine Daycare Ltd | Education | 2018 |
| Little-Elon Ltd | Education | 2026 |
| LIV Lettings Ltd | Construction | 2025 |
| Livigee Limited | Real estate | 2014 |
| LJ Property Solutions Ltd | Real estate | 2023 |
| LJA Inspection Services Limited | Professional & scientific | 2014 |
| LJD Electrical Services Ltd | Professional & scientific | 2024 |
| LJL Brickworx Ltd | Construction | 2019 |
| Ljljlw Services Ltd | Construction | 2024 |
| LJP Developments Ltd | Real estate | 2021 |
| LKL Flooring.Com Ltd | Wholesale & retail | 2013 |
| LKL Property Management Ltd | Real estate | 2020 |
| Lkoffshore Ltd | Professional & scientific | 2026 |
| LLW Site Services Ltd | Professional & scientific | 2025 |
| Lma-Pt Ltd | Other services | 2023 |
| LMB Property and Lettings Ltd | Real estate | 2026 |
| LMD Healthcare Limited | Health & social care | 2020 |
| Lmg-Tas Limited | Professional & scientific | 2016 |
| LMS Safely UK Limited | Other services | 2011 |
| LMW Access Ltd | Administrative & support | 2024 |
| Local Property Ltd | Real estate | 2024 |
| Local Removals & Storage Ltd | Transport & logistics | 2025 |
| Lodgeholiday.Com (NE) Ltd | Administrative & support | 2021 |
| Lomax Property Development Ltd | Real estate | 2022 |
| Longdon Properties Limited | Real estate | 2024 |
| Longhill MOT Centre Limited | Wholesale & retail | 2026 |
| Longmoor Systems Limited | Other services | 2007 |
| Longstaff Flooring Contractor Ltd | Construction | 2023 |
| Look to Lash Ltd | Wholesale & retail | 2020 |
| Loose Cannon Collective Ltd | Manufacturing | 2026 |
| Lotdan Holdings Ltd | Real estate | 2026 |
| Lottie's Cafe Ltd | Hospitality | 2025 |
| Lotus Palace Takeaway Ltd | Hospitality | 2019 |
| Love a Bargain Buy Ltd | Wholesale & retail | 2025 |
| Love-Flooring Limited | Wholesale & retail | 2021 |
| LOW Energy Lighting Solutions Ltd | Energy | 2008 |
| Loyalty Estates Property Group Ltd | Households | 2024 |
| Loyalty Homes Ltd | Real estate | 2020 |
| LP Pipeline Ltd | Professional & scientific | 2022 |
| LP Strat & Co Ltd | Financial services | 2017 |
| Lpcus Ltd | Professional & scientific | 2026 |
| LPL Engineering Ltd | Professional & scientific | 2025 |
| LPL Inspection Limited | Professional & scientific | 2003 |
| LQ Property Limited | Real estate | 2025 |
| LRA Solutions Limited | Construction | 2025 |
| LRC Consultants Ltd | Professional & scientific | 2022 |
| LRD QMS Limited | Professional & scientific | 2022 |
| LRW Access and Lifting Limited | Mining & quarrying | 2018 |