| Keuco UK Limited | Administrative & support | 2006 |
| Key Electrical Solutions Limited | Construction | 2012 |
| Key House Investments Limited | Professional & scientific | 2007 |
| Key Land Estates Limited | Construction | 2016 |
| Key to Learning International Limited | Professional & scientific | 2002 |
| KEZ Foods Ltd | Hospitality | 2025 |
| Kicadi Ltd | Real estate | 2019 |
| Kick Technic Ltd | Information & communication | 2019 |
| Kick-It AS Limited | Construction | 2009 |
| Kidfit Training Limited | Arts & recreation | 2014 |
| Kier BAM JV Ltd | Wholesale & retail | 2018 |
| Kilbridge Limited | Manufacturing | 1988 |
| Killa Waffles Limited | Hospitality | 2020 |
| Killeshandra Ltd | Professional & scientific | 2025 |
| Kinder Harmony Ltd | Health & social care | 2023 |
| Kinetic Business Limited | Professional & scientific | 2024 |
| Kingfisher Mews (ST Albans) Management Company Limited | Households | 2013 |
| Kingfisher Technology Limited | Administrative & support | 2015 |
| Kings (I.P.) Limited | Construction | 1975 |
| Kings Park Consulting Limited | Professional & scientific | 2019 |
| Kings Worldwide Limited | Wholesale & retail | 1947 |
| Kingsbury Farms Limited | Agriculture & fishing | 1988 |
| Kingsbury Town Management Company Limited | Arts & recreation | 2005 |
| Kinneil Consultants Limited | Professional & scientific | 2011 |
| Kinxus Ltd | Wholesale & retail | 2026 |
| Kirby Writing Limited | Arts & recreation | 2025 |
| Kiruna Tax and Surveying Limited | Professional & scientific | 2018 |
| KIT Wong Limited | Information & communication | 2013 |
| Kitchen 64 Limited | Hospitality | 2022 |
| Kitsune Holdings Limited | Information & communication | 2026 |
| Kiwi Electrical Solutions Limited | Construction | 2011 |
| Kiwi Greenfingers Ltd | Other services | 2005 |
| Kiwi Renovations Limited | Administrative & support | 2006 |
| KJ Consulting Corporation Ltd | Professional & scientific | 2018 |
| KJD Ltd | Construction | 2019 |
| KJD Solutions Limited | Information & communication | 2007 |
| KJW Marketing Ltd | Professional & scientific | 2025 |
| KL Law & HR Ltd | Administrative & support | 2019 |
| Klarc-Kal Assets Ltd | Professional & scientific | 2026 |
| KLE Construction Limited | Construction | 2022 |
| Kleiser Ltd | Professional & scientific | 2019 |
| Klejo Media Limited | Education | 2021 |
| Klotch Ltd | Financial services | 2021 |
| KM AZ Supplies Ltd | Wholesale & retail | 2024 |
| KMS Trading Limited | Wholesale & retail | 2010 |
| Knighton Foods Properties Limited | Real estate | 2014 |
| Knights Global Property Ltd | Real estate | 2012 |
| Knowledge Xchange Limited | Professional & scientific | 2005 |
| KNR Property Ltd | Real estate | 2023 |
| KNS Investments & Holdings Ltd | Real estate | 2016 |
| Koacom Ltd | Professional & scientific | 2018 |
| Koala & ROO Ltd | Construction | 2025 |
| Koala B2B Ltd | Administrative & support | 2024 |
| Kodak Graphic Communications Limited | Manufacturing | 1997 |
| Kodya Limited | Extraterritorial | 2022 |
| Koffee T Co. Ltd | Hospitality | 2025 |
| KOH Group Ltd | Financial services | 2025 |
| KOH IP Ltd | Administrative & support | 2025 |
| KOH Software Ltd | Information & communication | 2025 |
| Kohi Consultancy Limited | Professional & scientific | 2016 |
| Kojob Studio Ltd | Professional & scientific | 2022 |
| Kokone Limited | Professional & scientific | 2025 |
| Kokreate Works Ltd | Professional & scientific | 2025 |
| Kolbus Autobox Limited | Manufacturing | 1928 |
| Kong Real Estate Limited | Real estate | 2017 |
| Konnect Contracts Limited | Construction | 2009 |
| Konnexis Limited | Information & communication | 2026 |
| Konstra Ltd | Construction | 2025 |
| Koola Consulting Limited | Professional & scientific | 2006 |
| KOR Construction Ltd | Construction | 2008 |
| KOS Productions Ltd | Arts & recreation | 2025 |
| Kpco Property Management Ltd | Real estate | 2025 |
| Kpia Ltd | Other services | 2013 |
| KPK Consultancy Ltd | Professional & scientific | 2023 |
| KR Social Research Ltd | Professional & scientific | 2010 |
| KR70 Consulting Ltd | Professional & scientific | 2024 |
| Kraft Stationery Ltd | Wholesale & retail | 2018 |
| Krar Limited | Professional & scientific | 2014 |
| Krast Management Limited | Real estate | 2020 |
| Kresten Limited | Manufacturing | 2011 |
| Krish Projects Limited | Extraterritorial | 2022 |
| Kroovel Limited | Professional & scientific | 2025 |
| Krzysztof Gawronski Ltd | Wholesale & retail | 2023 |
| Ksmn Estates Ltd | Real estate | 2026 |
| KSP Medical Limited | Transport & logistics | 2023 |
| KSW Homes Ltd | Real estate | 2025 |
| KT London Specialists Limited | Hospitality | 2016 |
| KTF X Databricks LLP | | 2023 |
| KTF X Spacex LLP | | 2023 |
| KTJ Swim Limited | Professional & scientific | 2020 |
| Ktrw Engineering (Developments) Limited | Manufacturing | 2005 |
| KTZ Software Solutions Limited | Information & communication | 2013 |
| Kubiak Technology Limited | Information & communication | 1999 |
| Kubrick Music & Performance Limited | Information & communication | 2024 |
| Kudymov Ltd | Information & communication | 2026 |
| Kumi Impact Limited | Professional & scientific | 2025 |
| Kvass Properties Ltd | Other services | 2012 |
| KVZ Holdings Limited | Professional & scientific | 2022 |
| KW Design and Build Ltd | Construction | 2017 |
| KWR Property Services Ltd | Construction | 2006 |