| Kris & KAY Bars Ltd | Hospitality | 2025 |
| Kristian Marr Coaching Ltd | Education | 2025 |
| KS Hair & Beauty Limited | Other services | 2019 |
| KS Pratt & Co Limited | Professional & scientific | 2013 |
| KS Site Services Ltd | Construction | 2016 |
| KSS Automation Ltd | Professional & scientific | 2014 |
| KST Inspection Ltd | Professional & scientific | 2020 |
| KT Thompson Logistics Ltd | Transport & logistics | 2025 |
| KUE Skinlab Ltd | Other services | 2021 |
| Kulaz Ltd | Other services | 2025 |
| Kullar & Sidhu Developments Ltd | Construction | 2024 |
| Kurdish Translation Services 4U Ltd | Professional & scientific | 2024 |
| Kuyt Limited | Professional & scientific | 2007 |
| KW Inspections Ltd | Professional & scientific | 2024 |
| Kwacha Foods Ltd | Wholesale & retail | 2025 |
| KY UK Ltd | Transport & logistics | 2021 |
| Kyle Brown Logistics Ltd | Transport & logistics | 2025 |
| Kyle Cannings Limited | Professional & scientific | 2005 |
| Kyros Consultancy Limited | Information & communication | 2007 |
| L & C Skip Hire Limited | Administrative & support | 2010 |
| L & L Partners Limited | Wholesale & retail | 2020 |
| L & R Houses Limited | Real estate | 2024 |
| L & R Intertrade Ltd | Professional & scientific | 2007 |
| L & S Decorators Yarm Ltd | Construction | 2025 |
| L a B Academy Ltd | Education | 2019 |
| L C Kirtley Ltd | Manufacturing | 2025 |
| L C N Property Ltd | Real estate | 2020 |
| L J Najeenus Retail Ltd | Wholesale & retail | 2020 |
| L JOHNSTON78 Operations Ltd | Professional & scientific | 2025 |
| L&D Estate Management Ltd | Households | 2025 |
| L&G Driveways & Patios Limited | Administrative & support | 2025 |
| L&G Entertainment Ltd | Arts & recreation | 2026 |
| L.A. Dale Ltd | Agriculture & fishing | 2025 |
| L.A.V Developments Ltd | Real estate | 2023 |
| L.D.W Restaurant Group Ltd | Hospitality | 2026 |
| L.R.C. Inspection Services Limited | Professional & scientific | 2015 |
| L2A Energy Ltd | Administrative & support | 2021 |
| LA Porto Italiano Norton Ltd | Hospitality | 2026 |
| LA Porto Norton Ltd | Hospitality | 2018 |
| Lacafe, Latin American Coffee Ltd | Hospitality | 2025 |
| Lace Pro Limited | Wholesale & retail | 2023 |
| Lacelush Ltd | Wholesale & retail | 2026 |
| Ladnan Ltd | Construction | 2024 |
| Lady Marmalade Events Ltd | Other services | 2025 |
| Lady Physique Laboratory UK Ltd | Education | 2023 |
| Laidler Engineering Ltd | Professional & scientific | 2026 |
| Lakeshore Investments Limited | Households | 2020 |
| Lakeview Group Ltd | Construction | 2023 |
| Lakeys Driveways Ltd | Administrative & support | 2025 |
| Lakha Associates Ltd | Administrative & support | 2017 |
| Lakota Hub C.I.C. | Education | 2015 |
| Lamb Management & Consulting Ltd | Professional & scientific | 2025 |
| Lambton Holdings Ltd | Hospitality | 2021 |
| Land Brickwork Ltd | Construction | 2026 |
| Land of Make Believe Ltd | Arts & recreation | 2018 |
| Land-Star Express Limited | Transport & logistics | 2021 |
| Lanesystems Limited | Information & communication | 2003 |
| Langford Consultancy Limited | Professional & scientific | 1992 |
| Langford Rentals Limited | Hospitality | 1998 |
| Langthorne Properties Ltd | Professional & scientific | 2025 |
| Langworth Resources Limited | Other services | 2009 |
| Lanthwaite Property Ltd | Real estate | 2019 |
| Large Group Limited | Construction | 2022 |
| Larock Limited | Manufacturing | 2011 |
| Larsen Logistics Ltd | Transport & logistics | 2023 |
| Laser Cleaning Systems Limited | Administrative & support | 2026 |
| Lashbrooks.Com Limited | Wholesale & retail | 2012 |
| Later Life Planning Associates Ltd | Financial services | 2014 |
| Latos Cardiff Ltd | Information & communication | 2023 |
| Latos Carlisle Ltd | Information & communication | 2026 |
| Latos Data Centre Ltd | Information & communication | 2021 |
| Latos East Durham Ltd | Information & communication | 2026 |
| Latos Leeds Ltd | Information & communication | 2026 |
| Latos Manchester Ltd | Information & communication | 2023 |
| Latos Nottingham Ltd | Information & communication | 2026 |
| Latos Teesside Ltd | Information & communication | 2023 |
| Latos Wigan Ltd | Information & communication | 2023 |
| Launch Northeast Limited | Wholesale & retail | 2023 |
| Launchpad Digital Limited | Professional & scientific | 2010 |
| Lawan Group Limited | Hospitality | 2025 |
| Laws Property Rentals Ltd | Real estate | 2022 |
| Lawson Care Services Ltd | Public administration | 2026 |
| Layfield Holdings Limited | Financial services | 2017 |
| Layla Sky Ltd | Professional & scientific | 2025 |
| LBB Leisure Sunderland Limited | Hospitality | 2010 |
| LBB13 Limited | Construction | 2023 |
| Lbinn Ltd | Hospitality | 2022 |
| Lbslater Ltd | Real estate | 2022 |
| LC Services NE Limited | Water & waste | 2025 |
| LC Windtech Ltd | Manufacturing | 2025 |
| LCM Civils Ltd | Construction | 2016 |
| Ldmc Properties Limited | Real estate | 2021 |
| Ldmeu Limited | Wholesale & retail | 2021 |
| LE Carbone(Holdings)Limited | Manufacturing | 1930 |
| LE Raaj Fine Indian Ltd | Hospitality | 2021 |
| Lead North Limited | Professional & scientific | 2016 |
| Leafband Limited | Other services | 1991 |
| Leak Aware Ltd | Water & waste | 2020 |
| Leaps & Bounds Dog Services Ltd | Administrative & support | 2020 |
| Learnfibre Limited | Extraterritorial | 2021 |