| Knight Contracts Ltd | Real estate | 2019 |
| Knightly Window Films Ltd | Other services | 2018 |
| KNN Retail Limited | Wholesale & retail | 2022 |
| KO Imports Limited | Wholesale & retail | 2004 |
| Kobin Consulting Ltd | Information & communication | 2022 |
| Konnekt Ltd | Information & communication | 2018 |
| Konstantinos Georgalis Ltd | Hospitality | 2023 |
| KP Properties & Design Ltd | Real estate | 2022 |
| KRC Classic & Sports Cars Ltd | Wholesale & retail | 2023 |
| Kris Developments Limited | Construction | 2019 |
| KRS Property Invest Ltd | Real estate | 2024 |
| KRS Wellness Ltd | Other services | 2024 |
| Krypton FX Ltd | Information & communication | 2014 |
| Kshvac Ltd | Construction | 2022 |
| Kstork Data Cleansing and Compliance Services Limited | Information & communication | 2019 |
| KTA Accountants Ltd | Professional & scientific | 2023 |
| KW Roads Ltd | Real estate | 2021 |
| KYJ Limited | Education | 2025 |
| L & C Developments Essex Limited | Construction | 2024 |
| L & M Property (SE) Ltd | Real estate | 2025 |
| L C Drylining Limited | Construction | 2015 |
| L V Group Rentals Ltd | Administrative & support | 2025 |
| L West and Sons Ltd | Construction | 2023 |
| L&D Hospitality Management Ltd | Hospitality | 2025 |
| L&J Multiservices Limited | Administrative & support | 2024 |
| L'Autentica Investments Ltd | Professional & scientific | 2024 |
| L'Autentica Solutions Ltd | Professional & scientific | 2025 |
| L.A. Maintenance Limited | Construction | 1989 |
| L.J.Green Construction Ltd | Construction | 2002 |
| L.Page Motors Limited | Real estate | 1960 |
| LA Gardening Landscapes Limited | Other services | 2024 |
| LA Gardening Limited | Other services | 2016 |
| Labworldx Limited | Wholesale & retail | 2013 |
| Laima R Limited | Health & social care | 2022 |
| Lakey Building Services Limited | Construction | 2026 |
| Lambourne Investments Limited | Professional & scientific | 1999 |
| Lambs Agency Ltd | Health & social care | 2019 |
| Landmark Property Investments (UK) Limited | Real estate | 2000 |
| Lanefild LLP | | 2011 |
| Lanister UK Limited | Health & social care | 2020 |
| Lara Lettings & Sales Ltd | Real estate | 2023 |
| Latchetts Lettings Ltd | Real estate | 2022 |
| LAU Associates Company Ltd | Other services | 2015 |
| Launchlayer Ltd | Information & communication | 2025 |
| Laurie Wood Associates Limited | Professional & scientific | 2014 |
| Lawbailiff North West Ltd | Professional & scientific | 2016 |
| LB Tech Solutions Ltd | Information & communication | 2013 |
| LB Estates Ltd | Real estate | 2013 |
| Lbcg Estates Ltd | Real estate | 2022 |
| Lbfs Accountants Ltd | Professional & scientific | 2014 |
| Lbfs Consultancy Ltd | Financial services | 2016 |
| Lbfs Finance Ltd | Financial services | 2025 |
| Lbfs Holdings Ltd | Financial services | 2022 |
| Lbfs Outsourcing Ltd | Administrative & support | 2022 |
| LBL Mechanical Limited | Construction | 2024 |
| LBM Construction Essex Limited | Extraterritorial | 2018 |
| LBM Construction Services Ltd | Construction | 2009 |
| LBM Lettings Ltd | Real estate | 2017 |
| LCA Investments (SE) Ltd | Real estate | 2025 |
| LCH Stone Worktops Ltd | Construction | 2020 |
| LCW Estates Limited | Real estate | 2026 |
| LCW GAS Limited | Construction | 2022 |
| LDE7 Ltd | Professional & scientific | 2000 |
| LE Bela Cafe Ltd | Hospitality | 2026 |
| Le'Hair Limited | Other services | 2017 |
| Leadspecialist Ltd | Professional & scientific | 2023 |
| Learning Solutions Today Ltd | Education | 2019 |
| Learning to BE Ltd | Health & social care | 2021 |
| Lebac Holdings Ltd | Financial services | 2024 |
| Lech Seal Healthcare Ltd | Health & social care | 2022 |
| Ledge-Ent Limited | Health & social care | 2023 |
| Leeanjo Properties Limited | Real estate | 2024 |
| Legal Alliance (UK) Limited | Professional & scientific | 1996 |
| Legal Indemnity (UK) Limited | Professional & scientific | 2010 |
| Leidos Industrial Engineers Limited | Professional & scientific | 1983 |
| Lemon Groundwork Solutions Ltd | Manufacturing | 1978 |
| Lemon Steel Services Limited | Manufacturing | 1991 |
| LEN Moto Ltd | Wholesale & retail | 2025 |
| Leon C. Productions Limited | Arts & recreation | 2002 |
| LES Rochelas Consulting Ltd | Professional & scientific | 2022 |
| Levi Dana Limited | Health & social care | 2013 |
| Lewingtons Mastic Ltd | Construction | 2021 |
| Lewis Developments Ltd | Real estate | 2017 |
| Lewjet Ltd | Water & waste | 2024 |
| LG Digger Hire Ltd | Other services | 2020 |
| LGS Holdings Limited | Financial services | 2016 |
| LGS Trustee Limited | Financial services | 2023 |
| Lienna Property Group Ltd | Construction | 2024 |
| Life Perspective Ltd | Education | 2023 |
| Lifesafe Consumer Limited | Manufacturing | 2026 |
| Lifesafe Holdings Limited | Financial services | 2015 |
| Lifesafe Technologies Limited | Manufacturing | 2015 |
| Lifting, Access, Drone & Steam Limited | Construction | 2026 |
| Lily Grace Safety Ltd | Professional & scientific | 2023 |
| Limbachia Consulting Services Limited | Administrative & support | 2013 |
| Lime BDS Ltd | Construction | 2010 |
| Lincoln Aviation Ltd | Transport & logistics | 2021 |
| Ling Recruitment Limited | Construction | 2015 |
| Lion of London Limited | Administrative & support | 2020 |
| Lionheart & Daughter Ltd | Professional & scientific | 2025 |