| Knight Errant Ltd | Other services | 2025 |
| Knight Plumbing-Heating-Mechanical Services Limited | Construction | 2013 |
| Knocking on Devon's Door Ltd | Real estate | 2026 |
| Knotts Clothing Ltd | Wholesale & retail | 2017 |
| Knotts International Ltd | Real estate | 2021 |
| Knowlegence Limited | Information & communication | 2016 |
| Koaj Ltd | Health & social care | 2023 |
| Kocco Limited | Public administration | 2025 |
| Kodex UN Ltd | Information & communication | 2024 |
| KOF Technology Services Limited | Information & communication | 2024 |
| Koiruk Trade Ltd | Wholesale & retail | 2025 |
| Koko's Cakes Ltd | Manufacturing | 2020 |
| Kolemole Ltd | Real estate | 2025 |
| Kollins Group Ltd | Construction | 2020 |
| Koma Solutions Limited | Administrative & support | 2018 |
| Komaz Ltd | Professional & scientific | 2024 |
| Konadu Heritage Limited | Financial services | 2022 |
| Koncept Kare Ltd | Health & social care | 2024 |
| Koping Ltd | Administrative & support | 2016 |
| Korean Beauty Distribution Ltd | Wholesale & retail | 2026 |
| Korko Limited | Manufacturing | 2017 |
| Korne Beauty Limited | Other services | 2018 |
| Kory Strategic Solutions Limited | Information & communication | 2017 |
| Kovinvw Ltd | Financial services | 2022 |
| KP Boutique Limited | Wholesale & retail | 2025 |
| Kpdm Cleaning Ltd | Administrative & support | 2018 |
| KPM Accounts Limited | Professional & scientific | 2012 |
| KR Trade Ltd | Wholesale & retail | 2017 |
| KRA Brown Electrical Services Limited | Administrative & support | 2007 |
| KRA Brown Group Limited | Financial services | 2023 |
| Krafthaus Group Limited | Professional & scientific | 2016 |
| Kramer LHC Limited | Professional & scientific | 2017 |
| Krishna ENT Limited | Health & social care | 2025 |
| Kristian Smith Plastering Limited | Construction | 2014 |
| Kristian Smith Properties Ltd | Real estate | 2023 |
| Krsytal-Pearl Limited | Health & social care | 2018 |
| KS 337 Ltd | Real estate | 2024 |
| KTK Propertyservices Ltd | Real estate | 2021 |
| Kuba Polish Delicatessen Ltd | Wholesale & retail | 2019 |
| Kubus Express Limited | Wholesale & retail | 2026 |
| Kuperiks Ltd | Wholesale & retail | 2016 |
| KVC Global Resources Ltd | Real estate | 2017 |
| KVR Property Ltd | Real estate | 2025 |
| KW IT Services Ltd | Extraterritorial | 2020 |
| KWAM2 Ltd | Information & communication | 2025 |
| Kwan Brothers UK Limited | Wholesale & retail | 2014 |
| Kwapong Health CIC | Information & communication | 2026 |
| Kwesterman Ltd | Construction | 2017 |
| KWP Health Limited | Health & social care | 2023 |
| Kyndi Care Limited | Information & communication | 2016 |
| Kyndi Limited | Administrative & support | 2015 |
| Kyne Engineering Ltd | Wholesale & retail | 2023 |
| L & J Consultancy Ltd | Construction | 2016 |
| L & P Recovery Limited | Administrative & support | 2015 |
| L & V Haulage Limited | Transport & logistics | 2026 |
| L Brown Associates Ltd | Construction | 2017 |
| L C Osteopathy Ltd | Health & social care | 2025 |
| L D Engineering Kent Ltd | Construction | 2025 |
| L Hatch Ltd | Arts & recreation | 2021 |
| L K Hair & Beauty Limited | Other services | 2014 |
| L Kingston Medical Limited | Health & social care | 2024 |
| L Matthews Surfacing Ltd | Construction | 2020 |
| L N PAY Consulting Ltd | Financial services | 2025 |
| L N Roofing Specialist Ltd | Construction | 2014 |
| L P Carpentry & Joinery Ltd | Construction | 2026 |
| L&N Real Estate Ltd | Real estate | 2026 |
| L&O Space Solutions Ltd | Professional & scientific | 2025 |
| L. SAV Limited | Health & social care | 2012 |
| L.A. Services (Nationwide) Limited | Construction | 2025 |
| L.A.R.S Decorators Ltd | Construction | 2026 |
| L.C.P. Engineering Co. Limited | Wholesale & retail | 1950 |
| L.E.M. Wyevill RTM Company Limited | Real estate | 2009 |
| L.S.W. Construction Ltd | Construction | 2009 |
| L.T.Rail Solutions Limited | Manufacturing | 2015 |
| LA Flooring Designs Limited | Construction | 2016 |
| LA Magnolia Limited | Hospitality | 2011 |
| LA Sani Enterprises Ltd | Hospitality | 2012 |
| La-Poly Plumbing and GAS Ltd. | Construction | 2016 |
| Labone London Ltd | Hospitality | 2025 |
| Labroides Limited | Administrative & support | 2020 |
| Lacbis UK Limited | Health & social care | 2011 |
| Lachi Services Ltd | Construction | 2024 |
| Ladbrooke Electrical Ltd | Manufacturing | 2019 |
| Laing Fire Limited | Construction | 2007 |
| Lake Couriers Limited | Transport & logistics | 2017 |
| Lake House Property Company Limited | Construction | 2013 |
| Lake Recruitment Limited | Administrative & support | 2018 |
| Lakshmi Bhagya Limited | Health & social care | 2021 |
| Lakshmi Properties International Ltd | Real estate | 2023 |
| LAL Home Improvements Limited | Construction | 2022 |
| Lala Learning Media Ltd | Education | 2025 |
| Laleham 2010 Limited | Administrative & support | 2010 |
| Lameda UK Ltd | Construction | 2019 |
| Lamkay Global Limited | Construction | 2016 |
| Lamora Ltd | Wholesale & retail | 2022 |
| Lampey Services Ltd | Administrative & support | 2019 |
| Lanana Ltd | Real estate | 2024 |
| Lancebox Limited | Construction | 1986 |
| Lanchris Pro Limited | Real estate | 2017 |
| Land & Home Commercials Ltd | Construction | 2025 |