| Kitchens by GUY Ltd | Wholesale & retail | 2021 |
| KJD Carpentry Ltd | Manufacturing | 2025 |
| KJH Flooring Ltd | Wholesale & retail | 2025 |
| KJW Cleaning Limited | Administrative & support | 2003 |
| KKZ Limited | Construction | 2014 |
| Kleibson Teixeira Ltd | Transport & logistics | 2021 |
| KLS Publishing Ltd | Information & communication | 2020 |
| KM Hair and Beauty Ltd | Other services | 2018 |
| Kmoil Ltd | Other services | 2018 |
| KMR Haulage Essex Limited | Transport & logistics | 2012 |
| Knead Food Limited | Manufacturing | 2010 |
| Knelstrom Ltd | Information & communication | 2016 |
| Knight Controls Holdings Limited | Financial services | 2024 |
| Knight Controls Limited | Administrative & support | 2004 |
| Knightland Developments Group Limited | Construction | 2022 |
| Knightland Developments Ltd | Construction | 2020 |
| Knights Lodge (Braintree) Management Company Limited | Real estate | 1983 |
| Kocycle Limited | Information & communication | 2018 |
| Kopeck Limited | Wholesale & retail | 2025 |
| Kram Computer Consultants Limited | Information & communication | 1989 |
| Kraze Services Limited | Administrative & support | 2019 |
| Krenovate Ltd | Construction | 2016 |
| Kristina Ryan Ltd | Health & social care | 2025 |
| KRS Maintenance Ltd | Other services | 2013 |
| KRS Roofing Ltd | Construction | 2021 |
| KS Air Conditioning Ltd | Construction | 2025 |
| Ksje Ltd | Professional & scientific | 2017 |
| KSM London Properties Limited | Real estate | 2016 |
| Kulbik Ltd | Other services | 2022 |
| Kurapati E - Commerce UK Ltd | Wholesale & retail | 2018 |
| Kurapati Homes Ltd | Real estate | 2019 |
| L & B Technical Services Ltd | Professional & scientific | 2006 |
| L & C Security Solutions Limited | Professional & scientific | 2019 |
| L & S Residential Limited | Real estate | 2020 |
| L & S Structures (UK) Limited | Construction | 2010 |
| L a Cars (Braintree) Limited | Wholesale & retail | 2014 |
| L Daughters Wright Limited | Other services | 2024 |
| L I B Electrical Limited | Construction | 2013 |
| L N Parts Ltd | Wholesale & retail | 2011 |
| L&Lnastase Ltd | Transport & logistics | 2020 |
| L.Cullen Services Ltd | Construction | 2024 |
| L.G. UK Services Limited | Real estate | 2003 |
| L.M.Services (Essex) Ltd | Construction | 2026 |
| LA Galerie D'Art Limited | Wholesale & retail | 2024 |
| LA Lambourne Ltd | Professional & scientific | 2013 |
| La'Shomehelp Ltd | Administrative & support | 2025 |
| Labcare Service Limited | Manufacturing | 2010 |
| Labels 2000 Limited | Wholesale & retail | 2000 |
| Labtech.Investments Ltd | Financial services | 2025 |
| Lacazette Limited | Professional & scientific | 2025 |
| Lactosan (UK) Limited | Wholesale & retail | 2002 |
| Lactosan Holdings Limited | Professional & scientific | 1992 |
| Lada Beauty Limited | Other services | 2023 |
| Ladybird Consulting Ltd | Construction | 2026 |
| Lambert Chapman LLP | | 2007 |
| Lambert William Property Group Ltd | Real estate | 2023 |
| Lane Medical Services Ltd | Health & social care | 2026 |
| Lane Physiotherapy Holdings Limited | Financial services | 2025 |
| Lane Physiotherapy Limited | Health & social care | 2006 |
| Langdon Decorators Limited | Construction | 2013 |
| Lanstalgia UK Ltd | Hospitality | 2021 |
| Larchwood Farm Ltd | Agriculture & fishing | 2022 |
| Lares Holding Ltd | Financial services | 2025 |
| Lares Property Services Limited | Real estate | 2022 |
| Larkshall Ltd | Construction | 2021 |
| Lashbysilv Ltd | Other services | 2025 |
| Laszio Domiciliary Care Ltd | Health & social care | 2025 |
| Lateromedial Home Care Services Ltd | Health & social care | 2025 |
| Laughing Jackal Limited | Information & communication | 2005 |
| Laura Butler Ltd | Professional & scientific | 2018 |
| Laurence Chung Limited | Professional & scientific | 2021 |
| Law & Sons Ltd | Other services | 2016 |
| Lawlor Taxis Ltd | Transport & logistics | 2017 |
| Lawtech.Investments Ltd | Financial services | 2025 |
| LAYER8 Leathers Ltd | Wholesale & retail | 2013 |
| LBG Construction Ltd | Construction | 2024 |
| LC Executive Travel Ltd | Transport & logistics | 2026 |
| LCL Sales Ltd | Real estate | 2025 |
| LDN Auto Services Ltd | Wholesale & retail | 2023 |
| LDN Horticulture Ltd | Administrative & support | 2019 |
| Leadenhall Adjusting Limited | Extraterritorial | 2018 |
| Leadenhall International Limited | Other services | 2018 |
| Lean & Wild Ltd | Manufacturing | 2026 |
| LEARN2PLAY2LEARN Limited | Education | 2023 |
| Learning & Training Venture Ltd | Education | 2022 |
| Learning Pathways Academy | Education | 2012 |
| Leeps Medical Ltd | Health & social care | 2020 |
| Leeway Drylining Limited | Construction | 2026 |
| Leeway Facades Limited | Construction | 2016 |
| Legal Comfort Ltd | Professional & scientific | 2020 |
| Legends Sports and Pool Bar Limited | Arts & recreation | 2015 |
| Leigh Maddern Stunts Ltd | Arts & recreation | 2015 |
| Lekka Enterprises Ltd | Information & communication | 2017 |
| Lemans Gym Ltd | Arts & recreation | 2018 |
| Lenicookz Limited | Hospitality | 2025 |
| LEO Vpns Ltd | Information & communication | 2024 |
| Leos Lettings Ltd | Hospitality | 2026 |
| Lepal Ltd | Wholesale & retail | 2020 |
| Levare Gravis Ltd | Professional & scientific | 2024 |
| Levio Lifts Ltd | Manufacturing | 2025 |