| Kinson Limited | Construction | 1987 |
| Kinson Real Estate Management Limited | Real estate | 1987 |
| Kirkaldy Internet Services Limited | Professional & scientific | 1995 |
| KIT Car Electronics Limited | Manufacturing | 2017 |
| KIT Speakman (Braxted) Limited | Agriculture & fishing | 2001 |
| KJ Blake Ltd | Transport & logistics | 2025 |
| KJR Homes Limited | Real estate | 2021 |
| Klipcraze Ltd | Arts & recreation | 2013 |
| Knights Coaches Limited | Transport & logistics | 2003 |
| KNV Seevices Ltd | Information & communication | 2026 |
| Kofaa Services Company Ltd | Administrative & support | 2020 |
| Koru International Freight (UK) Limited | Transport & logistics | 2007 |
| KP Analytical Ltd. | Manufacturing | 2013 |
| KPD 79 Limited | Administrative & support | 2024 |
| Kristall Investment Limited | Administrative & support | 2013 |
| Kristall Real Estate Limited | Administrative & support | 2016 |
| Kristall Realty Investments Limited | Real estate | 2016 |
| Kronos Capital Investments Limited | Administrative & support | 2014 |
| KRS Contracts Limited | Construction | 2023 |
| Ksoykandles Ltd | Manufacturing | 2025 |
| Kwikfast Distributors Limited | Wholesale & retail | 1990 |
| Kytes Props Ltd | Information & communication | 2024 |
| LA OSA Limited | Financial services | 2024 |
| LAB to Launch Limited | Professional & scientific | 2024 |
| Labelnet Asset Management Limited | Administrative & support | 2008 |
| Labelnet Ltd | Manufacturing | 1999 |
| Lacuna RO Hair Limited | Other services | 2025 |
| Lake Cycling UK Ltd | Wholesale & retail | 2023 |
| Lancashire Internet Services Limited | Professional & scientific | 1995 |
| Lancing Court Management Company Limited | Hospitality | 1989 |
| Land of Munchies Ltd | Hospitality | 2020 |
| Langford Grange Developments Limited | Administrative & support | 1984 |
| Lariplast UK Limited | Manufacturing | 2024 |
| LAS Installations Ltd | Manufacturing | 2004 |
| Lavender and Sage, Recruitment & HR Co. Ltd | Administrative & support | 2025 |
| LC Building and Maintenance Ltd | Construction | 2023 |
| LE Voyage Boutique Limited | Wholesale & retail | 2018 |
| Lean Icon Technology and Training Ltd | Information & communication | 2019 |
| Legacy Partners Group Limited | Financial services | 2025 |
| Legal Accounting Limited | Professional & scientific | 2009 |
| Leicestershire Internet Services Limited | Professional & scientific | 1995 |
| Leisure Assist Ltd | Manufacturing | 2021 |
| Leisurefix Ltd | Manufacturing | 2016 |
| Leonard Harris Property Limited | Households | 2021 |
| Lets Clean IT Limited | Professional & scientific | 2005 |
| Levy & Co Limited | Administrative & support | 2010 |
| Levy & Co Solicitors LLP | | 2009 |
| Levy Property Lettings Limited | Hospitality | 2023 |
| Lexden Electrical Services Limited | Construction | 2022 |
| Lexden Scaffolding Limited | Construction | 2021 |
| LEZ Ltd | Construction | 2021 |
| LG Interiors Ltd | Other services | 2017 |
| LG Pressure Cleaning Ltd | Administrative & support | 2025 |
| Licnil Services Ltd | Professional & scientific | 2021 |
| Light Guide Inc Ltd | Professional & scientific | 2022 |
| Lighthouse Global Service Limited | Administrative & support | 2015 |
| Lightning Sparks Ltd | Energy | 2016 |
| Lila Fashions Limited | Other services | 2022 |
| Lilleymead (Witham) Ltd | Hospitality | 2018 |
| Lily Valley Ltd | Real estate | 2023 |
| Limehouse Paperboard Mills Limited | Manufacturing | 1962 |
| Limitless Solutions Worldwide Ltd | Wholesale & retail | 2020 |
| Linche Limited | Health & social care | 2023 |
| Lincolnshire Internet Services Limited | Professional & scientific | 1995 |
| Lisa at Holts Ltd | Hospitality | 2024 |
| Liscot Ltd | Transport & logistics | 2025 |
| Little Beacon Ltd | Manufacturing | 2025 |
| Living Solutions Group Ltd | Administrative & support | 2025 |
| Livingstone International Holdings Ltd | Administrative & support | 2015 |
| Livmorr Ltd | Wholesale & retail | 2019 |
| LJC Development Ltd | Professional & scientific | 2010 |
| Ljccouriers Ltd | Transport & logistics | 2025 |
| LJD Analytics Limited | Professional & scientific | 2025 |
| LJJ Investments Ltd | Information & communication | 2025 |
| LKP Utility Solutions Limited | Construction | 2016 |
| LL Lashes Ltd | Wholesale & retail | 2019 |
| LL UK Services Ltd | Hospitality | 2011 |
| Lo-Ki Audio & Visual Ltd | Professional & scientific | 2018 |
| Lockside Electrical Contractors Ltd | Construction | 2021 |
| Logic Lane Solutions Limited | Information & communication | 2024 |
| Lola Build Ltd | Construction | 2025 |
| LOM International Ltd | Wholesale & retail | 2023 |
| London Dental Clinics Ltd | Health & social care | 2017 |
| London Enterprise Solutions Ltd | Information & communication | 2017 |
| London Internet Services Limited | Professional & scientific | 1995 |
| London Lead Roofing Limited | Construction | 2011 |
| London Polished Concrete Ltd | Construction | 2015 |
| London Sourcing Company Limited | Professional & scientific | 2016 |
| London Spine Clinic Limited | Extraterritorial | 1999 |
| Longhurstconstruction Ltd | Construction | 2026 |
| Longwood Ltd | Real estate | 2019 |
| Loopify Impact Limited | Professional & scientific | 2024 |
| Lorac Accounting Limited | Extraterritorial | 2003 |
| Louis Kingwill Ltd | Construction | 2014 |
| Love Amber X Limited | Manufacturing | 2015 |
| Love Heart Weddings (Crete) Limited | Administrative & support | 2016 |
| Lovisiri Ltd | Information & communication | 2026 |
| LPB Care Limited | Real estate | 2003 |
| LRC Logistics (UK) Ltd | Transport & logistics | 2018 |
| Lscg Newco Limited | Administrative & support | 2021 |