| Knights Legal Outfitters Ltd | Wholesale & retail | 2022 |
| Knotty Nora Ltd | Wholesale & retail | 2025 |
| Knowbody Ltd | Public administration | 2025 |
| Knowl Piece Business Park Management Company Limited | Real estate | 2007 |
| Knowl Piece Limited | Extraterritorial | 2001 |
| Knowl Piece Services Limited | Administrative & support | 2001 |
| Knowles Consultancy Limited | Other services | 2020 |
| Kobe Build Ltd | Construction | 2023 |
| Kohiti Ltd | Information & communication | 2011 |
| Komdhi Ltd | Other services | 2022 |
| Komflex Ltd | Wholesale & retail | 2015 |
| Konnetix Infrastructure Services Limited | Information & communication | 2015 |
| Konnetix Limited | Other services | 2012 |
| Kosy CKC Harrow Limited | Construction | 2023 |
| Kosy CKC Limited | Construction | 2022 |
| Kosy CKC Watford Limited | Construction | 2023 |
| KR Capital Investments Ltd | Hospitality | 2023 |
| Kristi DUR Ltd | Professional & scientific | 2025 |
| Kroko Ltd | Real estate | 2022 |
| Kropz PLC | Mining & quarrying | 2018 |
| Krucial Management Ltd | Wholesale & retail | 2018 |
| KSS Electrical Solutions Limited | Manufacturing | 2021 |
| KSS Property Group Limited | Real estate | 2026 |
| Kudo Back Office Ltd | Professional & scientific | 2018 |
| Kudos Colour Printers Limited | Manufacturing | 1997 |
| Kudos Memorabilia Limited | Wholesale & retail | 2015 |
| Kumari Chiropractic Limited | Health & social care | 2014 |
| Kuna Films Limited | Information & communication | 2020 |
| Kustom Clothing (Hitchin) Limited | Administrative & support | 2010 |
| Kvtc Ltd | Professional & scientific | 2021 |
| KW Livestock Trading Limited | Agriculture & fishing | 2017 |
| Kwik-E-Mart Ltd | Professional & scientific | 2022 |
| Kwwk Limited | Administrative & support | 2019 |
| Kynectx Limited | Professional & scientific | 2025 |
| L & R Extensions Ltd | Construction | 2013 |
| L & R Land Limited | Real estate | 2022 |
| L J Miller & Sons Ltd | Real estate | 2025 |
| L J P Projects Limited | Other services | 2011 |
| L Jennings Creative Limited | Arts & recreation | 2023 |
| L M Trading Limited | Real estate | 2008 |
| L Squared Lasers Ltd | Administrative & support | 2007 |
| L Stevens Consultancy Limited | Education | 2012 |
| L Walsh Flooring Limited | Construction | 2026 |
| L&G Travel Ltd | Administrative & support | 2024 |
| L&L Consultancy Group Ltd | Professional & scientific | 2019 |
| L&S Barton Ltd | Hospitality | 2025 |
| L&S Maths LLP | | 2023 |
| L. Trueman & Co. Limited | Information & communication | 1999 |
| L.E.L. Bathrooms & Kitchens Limited | Construction | 2018 |
| L.M. Law Ltd | Professional & scientific | 2022 |
| L.S Building & Grounds Maintenance Ltd | Arts & recreation | 2026 |
| LA Bella Vita Investments Ltd | Real estate | 2024 |
| LA Mode Homes Ltd | Real estate | 2014 |
| LA Petite Parfumerie Limited | Wholesale & retail | 2024 |
| LAA Pacific Ltd | Information & communication | 2026 |
| Lacerta Court Management Limited | Administrative & support | 2001 |
| Lackenden Ltd | Wholesale & retail | 2021 |
| Lacy Surveying Limited | Financial services | 2021 |
| Ladygrove Cottages Freehold Limited | Households | 2024 |
| Ladygrove Property Services Limited | Real estate | 2023 |
| Ladyheath Properties Limited | Real estate | 1999 |
| Ladywalk Holdings Limited | Construction | 2015 |
| LAI Limited | Administrative & support | 1999 |
| LAI Reserves Limited | Real estate | 2015 |
| Lake Goldsmith Solutions Limited | Information & communication | 2020 |
| Laltu Ltd | Professional & scientific | 2020 |
| Lalunah Ltd | Manufacturing | 2020 |
| Lambert & Co. Ltd | Construction | 2017 |
| Lamcom Ltd. | Wholesale & retail | 2014 |
| Lancing Homes Holding Limited | Real estate | 2022 |
| Land & Marine Environmental Limited | Manufacturing | 1997 |
| Lander Property Management Limited | Real estate | 2000 |
| Landmark Coaches Limited | Transport & logistics | 1998 |
| Landmark Vehicle Hire Limited | Transport & logistics | 2003 |
| Lane & Reliable Transport Ltd | Transport & logistics | 2025 |
| Lane One Limited | Professional & scientific | 2019 |
| Lanevo Property Development Ltd | Construction | 2021 |
| Langham House Investments Limited | Construction | 2004 |
| Langham Place Residents Company Limited | Households | 1995 |
| Langley Garage Ltd | Wholesale & retail | 2024 |
| Laniwyn Care Services Ltd | Health & social care | 2016 |
| Laniwyn Properties Ltd | Real estate | 2019 |
| Lanni's Taxis Ltd | Transport & logistics | 2020 |
| Lannock Foods Limited | Wholesale & retail | 2026 |
| Lannock Limited | Real estate | 2020 |
| Larentia Capital Limited | Hospitality | 2011 |
| Larentia Land Limited | Real estate | 2014 |
| Laser Cleaning Services UK Ltd | Extraterritorial | 2022 |
| Laser Cleaning UK Ltd | Administrative & support | 2022 |
| Laser Precision Ltd | Professional & scientific | 2013 |
| LAT Capital Ltd | Real estate | 2026 |
| Launch Insurance Brokers Limited | Financial services | 2014 |
| Laura Davis Mortgage & Life Services Ltd | Professional & scientific | 2014 |
| Lauramonika Ltd | Administrative & support | 2025 |
| Lavender Croft Co Limited | Households | 2000 |
| Lavender Financial Planners Limited | Financial services | 2018 |
| Lawrence Davies Consultancy Limited | Professional & scientific | 2013 |
| Laws Abel Ltd | Other services | 2025 |
| Layton Technology Limited | Information & communication | 1999 |
| LB Window Maintenance Limited | Construction | 2024 |