| Kids Breakfast and Supper Club Ltd | Wholesale & retail | 2015 |
| King's Road Dental Practice Ltd | Health & social care | 2010 |
| Kingbridge Ltd | Professional & scientific | 2024 |
| Kithe Limited | Professional & scientific | 2025 |
| KJR Security Ltd | Administrative & support | 2023 |
| KK Universal Limited | Health & social care | 2025 |
| KLS Hospitality Supplies Ltd | Hospitality | 2026 |
| KLS Tech Ltd | Information & communication | 2018 |
| KM Scientific QA Limited | Administrative & support | 2015 |
| Knight TV Ltd | Information & communication | 2019 |
| Kobbiminn Limited | Professional & scientific | 2022 |
| KOM Solutions Limited | Information & communication | 2023 |
| Konick Limited | Information & communication | 2003 |
| Kortes Limited | Information & communication | 2007 |
| Kral Barbers Limited | Other services | 2022 |
| Krharding Consultants Limited | Administrative & support | 2023 |
| KRT Design Ltd | Professional & scientific | 2022 |
| KS Financial Advisers Limited | Financial services | 2014 |
| KT Projects Limited | Construction | 2025 |
| KTH Building and Maintenance Ltd | Construction | 2016 |
| KTS Contracts Limited | Information & communication | 2018 |
| L J S Services Ltd | Information & communication | 2015 |
| L Stafford Carpentry Ltd | Manufacturing | 2024 |
| L.E.F Security Ltd | Construction | 2026 |
| L.W. Hoist Repair & Inspection Ltd | Manufacturing | 2026 |
| L4 London Ltd | Professional & scientific | 2017 |
| LA Concrete Floors Ltd | Construction | 2024 |
| LA Foret Property Company Limited | Real estate | 1994 |
| LA Mamá DE Amapola Ltd | Real estate | 2024 |
| LAB287 Limited | Information & communication | 2014 |
| Labyrinth Telecommunications Ltd | Information & communication | 2020 |
| Lakeside Regulatory Consulting Services Ltd | Professional & scientific | 2005 |
| Lakestay Cleans Ltd | Administrative & support | 2026 |
| Lakshmi Holdings Limited | Financial services | 2013 |
| Lakshmi Investments Limited | Financial services | 2015 |
| Lakshmi Online Shopping Limited | Wholesale & retail | 2020 |
| Lakshmi Professionals Limited | Professional & scientific | 2021 |
| Lambda One Ltd | Information & communication | 2019 |
| Lambert Psychological Services Limited | Other services | 2023 |
| Lamp & Daughter Limited | Arts & recreation | 2015 |
| Lander Ward Ltd | Wholesale & retail | 2022 |
| Landgreen Construction Ltd | Construction | 2016 |
| Landmark Maintenance Group Ltd | Construction | 2023 |
| Landmark Road Lining Ltd | Construction | 2014 |
| Landseer Catering Ltd | Hospitality | 2023 |
| Langdon Client Services Ltd | Health & social care | 2018 |
| Langdon Street (Tring) Management Limited | Households | 2017 |
| Langtry House Limited | Households | 1996 |
| Laniakea Limited | Information & communication | 2014 |
| Lansley RG Ltd | Administrative & support | 2025 |
| Lantic Associates Ltd | Professional & scientific | 2019 |
| LAP Maintenance Ltd | Construction | 2021 |
| Larus Consulting Ltd | Administrative & support | 2017 |
| Latbuild Construction Ltd | Construction | 2020 |
| Latrémolière LLP | | 2020 |
| Laura Stewart Ltd | Professional & scientific | 2017 |
| Laurel Consultancy 2019 Ltd | Professional & scientific | 2019 |
| Layis Landscaping Ltd | Administrative & support | 2023 |
| LCA2 Limited | Construction | 2021 |
| LD Animal Solutions Ltd | Agriculture & fishing | 2024 |
| LDH Construction Consulting Ltd | Professional & scientific | 2020 |
| Leadership Principles Ltd | Information & communication | 2018 |
| Leadtyme Ltd | Financial services | 2011 |
| Lean-B Limited | Professional & scientific | 2025 |
| Ledburn Developments Ltd | Construction | 2018 |
| Legit KIT Ltd | Administrative & support | 2022 |
| LF Consulting Solutions Ltd | Professional & scientific | 2023 |
| LFM Ventures Limited | Financial services | 2024 |
| LH Craft Ltd | Professional & scientific | 2026 |
| Liaison D'Etre Ukeig | Professional & scientific | 1993 |
| Liberty Developments (Bucks) Limited | Construction | 1994 |
| Library of Lives Limited | Information & communication | 2024 |
| Licensed Bar Management Services Limited | Arts & recreation | 2019 |
| Lighthouse HR Ltd | Administrative & support | 2016 |
| Linarex Limited | Information & communication | 2007 |
| Linguistik Ltd | Professional & scientific | 2022 |
| Liquidity Cube (UK) Ltd | Financial services | 2023 |
| Little Kahuna Films Limited | Information & communication | 2024 |
| Little Shop of Cheese Limited | Wholesale & retail | 2024 |
| Little Sloth Ltd | Wholesale & retail | 2021 |
| Little Valleys Properties Limited | Real estate | 2024 |
| Little White House Ltd. | Other services | 2015 |
| Littlewaffleshop Limited | Hospitality | 2023 |
| LIZ Oakley Communications Ltd | Professional & scientific | 2020 |
| LJL Mcallister Properties Ltd | Construction | 2015 |
| LJN Solutions Ltd | Information & communication | 2024 |
| Lloyd Advisory Limited | Professional & scientific | 2015 |
| Lloyd Donnelly Solicitors Limited | Professional & scientific | 2013 |
| LMT Retail Consulting Ltd | Professional & scientific | 2024 |
| Loft 68 Vintage Ltd | Wholesale & retail | 2015 |
| Loftman Leisure Ltd | Arts & recreation | 2017 |
| London Energies Ltd | Information & communication | 2024 |
| London Writers' Eclective Limited | Extraterritorial | 2020 |
| Long Haul Drivers Ltd | Transport & logistics | 2017 |
| Long White Digital Ltd | Information & communication | 2011 |
| Long's Electrical Limited | Construction | 2007 |
| Longcross Edgbaston Limited | Real estate | 2018 |
| Longfield Road (Tring) Management Company Limited | Households | 2013 |
| Longmate Consultants Ltd | Professional & scientific | 2014 |
| Lord Kadir Limited | Hospitality | 2018 |