| Kansara's Exclusive Luxury Chocolates Ltd. | Wholesale & retail | 2002 |
| Karz Limited | Health & social care | 2007 |
| Kat&Co Ltd | Hospitality | 2025 |
| Kate Brown Accountancy Limited | Professional & scientific | 2005 |
| Kayeburn Ltd | Information & communication | 2009 |
| Kaymay Services Limited | Extraterritorial | 2013 |
| Kaytone Limited | Professional & scientific | 2004 |
| KC Film Services Ltd | Professional & scientific | 2023 |
| KDR Services Limited | Professional & scientific | 2003 |
| Kenilly's Limited | Wholesale & retail | 2018 |
| Kennadys Limited | Other services | 2004 |
| Kent Car Park Holdings Limited | Transport & logistics | 2024 |
| Keri Systems UK Limited | Administrative & support | 1999 |
| Kerom Ltd | Hospitality | 2026 |
| Kerr 1 Limited | Extraterritorial | 2017 |
| Kershal & Co. Ltd | Professional & scientific | 2002 |
| Kesiah and Company Ltd | Information & communication | 2025 |
| Kettering Car Park Holdings Limited | Transport & logistics | 2026 |
| Kevgo Brands UK Ltd | Wholesale & retail | 2017 |
| Kevin Southwell Ltd | Wholesale & retail | 2002 |
| Keystone Facilities Management Limited | Administrative & support | 1997 |
| Kiara Investments Limited | Real estate | 2005 |
| Kick Drip Ltd | Wholesale & retail | 2021 |
| Kiln Park Estates Limited | Hospitality | 1959 |
| Kimber Travel Ltd | Administrative & support | 2025 |
| Kind Diamond Build Consortium Limited | Construction | 2015 |
| Kinesis Information Technology Limited | Information & communication | 2007 |
| King Ramps Limited | Education | 2006 |
| King Street Caterers Limited | Wholesale & retail | 1959 |
| Kings Langley Textiles Ltd | Wholesale & retail | 2007 |
| Kingscote Plant Ltd | Administrative & support | 2006 |
| Kingshill Accountants Limited | Extraterritorial | 1998 |
| Kingslee U.K. Limited | Wholesale & retail | 1993 |
| Kinsbourne Court Management Limited | Real estate | 1992 |
| Kinterlock Limited | Construction | 1990 |
| Kirby Colletti Limited | Real estate | 2003 |
| Kirkley Limited | Health & social care | 2003 |
| Kitchen Gallery (Sawbridgeworth) Limited | Construction | 2005 |
| KJ Loyal Courier Ltd | Transport & logistics | 2021 |
| KJW Osteopathy Limited | Other services | 2007 |
| Klgc Design Solution Limited | Manufacturing | 2002 |
| Kloofs of London Limited | Wholesale & retail | 2016 |
| Klotts Ltd | Financial services | 2024 |
| KMP Engineering Services Limited | Professional & scientific | 1999 |
| Knebworth Tandoori Limited | Hospitality | 2002 |
| Knights Armoury Ltd | Wholesale & retail | 2023 |
| Knights Cleaning Services Limited | Administrative & support | 2015 |
| Knights Court Limited | Real estate | 2007 |
| Knish Limited | Wholesale & retail | 2024 |
| Knocklong Estates Limited | Real estate | 2006 |
| Knowvolution Limited | Information & communication | 2001 |
| KPN Trustees Limited | Professional & scientific | 2021 |
| Kris Aromatics Limited | Hospitality | 1994 |
| KRL Construction Limited | Construction | 2000 |
| KU Contractors Limited | Construction | 2023 |
| Kubilay Property Holdings Ltd | Real estate | 2020 |
| KYD Consulting Limited | Information & communication | 2009 |
| L & M'S Little Acorns Limited | Real estate | 2005 |
| L B Precision Sheet Metal Works Limited | Manufacturing | 2003 |
| L F a Brickwork Limited | Construction | 2003 |
| L H Cook Plumbing, Heating & Renewables Limited | Construction | 2025 |
| L. UGO (Property) Company Limited | Real estate | 1972 |
| L.B.J. (Investments) Limited | Professional & scientific | 1995 |
| L.F. Logistics Limited | Transport & logistics | 1993 |
| LA Bonne Bouffe Limited | Hospitality | 2002 |
| LA Key Star Properties & Services Ltd | Real estate | 2022 |
| LAB Tots Learning System Limited | Wholesale & retail | 2021 |
| Labfix 2000 Limited | Manufacturing | 2007 |
| Lakemere Limited | Real estate | 1985 |
| Lakshmi Homes Ltd | Real estate | 2022 |
| Lamkin Builders Limited | Construction | 2006 |
| Lancaster Associates Limited | Administrative & support | 1999 |
| Lancaster Mews Residents Association Limited | Households | 1995 |
| Landforce Group Ltd | Agriculture & fishing | 2023 |
| Landmark Property Investments Limited | Other services | 1993 |
| Landworth Electrics Limited | Construction | 2007 |
| Langleetarn Limited | Financial services | 2007 |
| Langley Animal Care Ltd | Professional & scientific | 2025 |
| Langmoor Orchard (a B C D) Management Company Limited | Households | 1994 |
| Langmoor Orchard (E F G J) Management Company Limited | Real estate | 1995 |
| Lansglade Homes Limited | Administrative & support | 1981 |
| Larkwalk Properties Limited | Real estate | 1991 |
| Latitude 64 Limited | Professional & scientific | 2025 |
| Lavender Systems Limited | Administrative & support | 1994 |
| Laventure Inns Limited | Professional & scientific | 2003 |
| Law 2457 Limited | Professional & scientific | 2003 |
| Law Recruit.Co.Uk Limited | Professional & scientific | 2001 |
| Lawford Holdings Ltd | Financial services | 2023 |
| Layan Taxi Ltd | Transport & logistics | 2026 |
| Layston Lodge Management Co. Limited | Real estate | 1985 |
| LE Palm Estates Ltd | Real estate | 2022 |
| LEA Valley Narrowboat Company Limited | Transport & logistics | 1974 |
| LEA Valley Swimming Pools Limited | Other services | 2003 |
| Leading Edge Software Ltd. | Information & communication | 1991 |
| Learning Circle Limited | Education | 2002 |
| Leary Brothers Limited | Construction | 1998 |
| Leaside Timber & Builders Merchants Limited | Manufacturing | 1999 |
| LEE Electrical Limited | Construction | 1997 |
| Lees Heating Services Limited | Construction | 2004 |
| Leicester Waste Management Limited | Professional & scientific | 1999 |