| KJC Counselling Ltd | Health & social care | 2025 |
| KK Traders Ltd | Wholesale & retail | 2018 |
| KKS Engineering Ltd | Construction | 2024 |
| KKS Management Services Limited | Professional & scientific | 2008 |
| KLS Accountancy Services Ltd | Professional & scientific | 2025 |
| KMC Earley Ltd | Professional & scientific | 2017 |
| KMS Infotech Limited | Information & communication | 2009 |
| KN Intellectual Holdings Limited | Administrative & support | 2025 |
| Knapper Productions Limited | Professional & scientific | 2026 |
| KNG Group Ltd | Wholesale & retail | 2020 |
| Knight Webb Sustainability Limited | Professional & scientific | 2024 |
| Koburg Limited | Arts & recreation | 2021 |
| KOG Security Ltd | Administrative & support | 2024 |
| Kogels of Abingdon Limited | Construction | 2013 |
| KOM - Systems Limited | Information & communication | 2013 |
| Koret Consulting Limited | Administrative & support | 2026 |
| Koru Consulting Limited | Professional & scientific | 2001 |
| Kottu Club Ltd | Hospitality | 2025 |
| Kovner Consultancy Limited | Information & communication | 2021 |
| Kprayner Ltd | Wholesale & retail | 2009 |
| Krastar Ltd | Wholesale & retail | 2017 |
| Kreative Barn Ltd | Information & communication | 2021 |
| Kreative Events Limited | Professional & scientific | 2015 |
| Kreha Mechanical Limited | Information & communication | 2016 |
| Krinkels UK Limited | Administrative & support | 1989 |
| Krisolyte Ltd | Wholesale & retail | 2026 |
| Kristian LEE Winslade Ltd | Wholesale & retail | 2025 |
| KRN Fitness Limited | Arts & recreation | 2019 |
| KS Auto Refurbishment Ltd | Wholesale & retail | 2018 |
| KS Change Consultancy Limited | Information & communication | 2025 |
| KS UK Couriers Ltd | Transport & logistics | 2023 |
| KSR Commercial Limited | Construction | 2019 |
| Kubatan Kitchen Ltd | Hospitality | 2023 |
| Kuljinder and Navita Properties Partnership LLP | | 2024 |
| Kulkumry Coffee: the Blesséd Brew Ltd | Manufacturing | 2024 |
| Kumar Financial Services Ltd | Professional & scientific | 2018 |
| Kuriosity Ltd | Professional & scientific | 2025 |
| L & C Hospitality Limited | Hospitality | 2022 |
| L & H Property Ltd | Extraterritorial | 2024 |
| L T Accountancy Ltd | Professional & scientific | 2023 |
| L'Floof Limited | Manufacturing | 2022 |
| L. Moran Heating Ltd | Construction | 2012 |
| L. Moran Property Investment Ltd | Real estate | 2026 |
| L.A. Lockhart Plant Hire Limited | Construction | 2000 |
| L.E.H Holdings Ltd. | Real estate | 2022 |
| LA Montana Ltd | Wholesale & retail | 2021 |
| LA Rotisserie Ltd | Hospitality | 2023 |
| LAB Fifty Limited | Professional & scientific | 2025 |
| LAB Music Limited | Wholesale & retail | 2005 |
| LABELS4UDESIGNERS4U Limited | Wholesale & retail | 2017 |
| Laborare Ltd | Professional & scientific | 2025 |
| Lacewood Consulting Ltd | Information & communication | 2024 |
| Lacey's Hair & Beauty Supplies Limited | Wholesale & retail | 2005 |
| Lacey-Stewart Holdings Ltd | Wholesale & retail | 2023 |
| Lake Light Solutions Ltd | Professional & scientific | 2022 |
| Lakestar Capital LLP | | 2012 |
| Lala UK Limited | Hospitality | 2020 |
| Lama Barry Ltd | Professional & scientific | 2018 |
| Land Home Ltd | Construction | 2018 |
| Langham RTM Company Ltd | Households | 2010 |
| Lansdowne Ventures Ltd | Manufacturing | 2026 |
| Larbrax Consulting Limited | Professional & scientific | 2014 |
| Lasculpted Limited | Wholesale & retail | 2025 |
| Latam Business Limited | Professional & scientific | 2023 |
| Latens Ltd | Wholesale & retail | 2026 |
| Launchtree Studios Ltd | Information & communication | 2025 |
| Launton Bridge Development Company Limited | Real estate | 1966 |
| Launton Sports & Social C.I.C. | Hospitality | 2019 |
| Lauren Ruby Hair Limited | Other services | 2018 |
| Lavisionuk Limited | Manufacturing | 2006 |
| Lawn Bowls Supplies Ltd | Wholesale & retail | 2021 |
| Lawnflite Limited | Extraterritorial | 1988 |
| LB HR Consultancy Ltd | Administrative & support | 2019 |
| Lb-Arrival Ltd | Wholesale & retail | 2024 |
| LBC Group Holdings Limited | Professional & scientific | 2023 |
| LC Investment Property Ltd | Real estate | 2024 |
| LCR Accounting Limited | Professional & scientific | 2022 |
| Lcwr Consulting Ltd | Professional & scientific | 2024 |
| LDN Stone Ltd | Construction | 2017 |
| Leafgrove Limited | Agriculture & fishing | 1998 |
| Leafield Care Ltd | Health & social care | 2019 |
| Lean CI Solutions Limited | Information & communication | 2007 |
| Learnership Ltd | Professional & scientific | 2000 |
| Learning and Management Ltd | Education | 2023 |
| Learning Ecology Ltd | Professional & scientific | 2001 |
| Lebink Logistics Ltd | Real estate | 2023 |
| Lecheno Ltd | Wholesale & retail | 2016 |
| Leckie-Kershaw Ltd | Information & communication | 2018 |
| Leda Group Holdings Limited | Financial services | 2023 |
| Leda Holiday Lets Limited | Hospitality | 2023 |
| Leda Properties Limited | Agriculture & fishing | 1976 |
| LEE Pontefract Plumbing and Home Improvements Ltd | Construction | 2018 |
| LEE Wanless Plumbing and Heating Limited | Construction | 2009 |
| Legend LIM Limited | Wholesale & retail | 2013 |
| Legends Podiatry Limited | Health & social care | 2026 |
| Legion Fitness Equipment Ltd | Wholesale & retail | 2021 |
| Leigh Rushworth Limited | Transport & logistics | 1993 |
| Leighton Coachworks Ltd | Wholesale & retail | 2013 |
| Lemonade Innovation Limited | Administrative & support | 2025 |
| Lena Transport Limited | Transport & logistics | 2010 |