| Knee Treatment Ltd | Health & social care | 2024 |
| Knife & Fork Food Limited | Hospitality | 1999 |
| Knight C Ltd | Construction | 2017 |
| Knight Carlotta Developments Limited | Wholesale & retail | 2025 |
| Knight Carlotta Properties Ltd | Real estate | 2024 |
| Knight Facades Ltd | Construction | 2019 |
| Knight Resource Management Limited | Administrative & support | 2017 |
| Knight Vintage Limited | Wholesale & retail | 2024 |
| Knighthood Security Ltd | Administrative & support | 2026 |
| Knightkreation Ltd | Wholesale & retail | 2025 |
| Knightmoss Limited | | 1976 |
| Knighton Court Management Company Limited | Households | 1995 |
| Knights Blinds Ltd | Wholesale & retail | 2020 |
| Knightsave Consultancy Limited | Administrative & support | 2017 |
| Knightsbridge Fire Group Ltd | Administrative & support | 2015 |
| Knightsbridge Products Ltd | Wholesale & retail | 2017 |
| Knightsbridge Supermarkets Limited | Wholesale & retail | 2011 |
| Knightsbridge Wholesale Ltd | Wholesale & retail | 2016 |
| Knitted Mitten Limited | Information & communication | 2012 |
| KNK Design Studio Ltd | Professional & scientific | 2024 |
| Knms Embroidery Ltd | Wholesale & retail | 2021 |
| Knntoct Ltd | Wholesale & retail | 2025 |
| Knock the Door Limited | Wholesale & retail | 2014 |
| Knockback Games Ltd | Information & communication | 2022 |
| Knocknagoney Ltd | Other services | 2018 |
| Knocknagoney Park Ltd | Financial services | 2016 |
| Knockoutsound Limited | Information & communication | 2023 |
| Knoell Animal Health Limited | Professional & scientific | 1998 |
| Knoell UK Holdings Limited | Professional & scientific | 2003 |
| Knomo (Online) Ltd | Wholesale & retail | 2021 |
| Knomo (Wholesale) Ltd | Wholesale & retail | 2021 |
| Knoops (Clapham) Ltd | Hospitality | 2019 |
| Knot Capital Ltd | Financial services | 2024 |
| Knot Power Limited | Professional & scientific | 2024 |
| Knotco Wholesale Ltd | Wholesale & retail | 2019 |
| Knott Construction Consultancy Limited | Construction | 2026 |
| Know Your Onions Ltd | Professional & scientific | 2025 |
| Knowdyn Ltd | Information & communication | 2021 |
| Knowlen Trading Ltd | Construction | 2020 |
| Knowles Contractor Services Ltd | Professional & scientific | 2018 |
| Known Solutions Ltd | Professional & scientific | 2025 |
| Knowvia Ltd | Education | 2025 |
| Knox & Wells EOT Limited | Professional & scientific | 2026 |
| Knox & Wells Group Limited | Financial services | 2026 |
| Knox & Wells Holdings Limited | Construction | 1994 |
| Knox & Wells Limited | Construction | 1935 |
| Knox Road Restorations Limited | Health & social care | 2023 |
| Knoziz Ltd | Arts & recreation | 2019 |
| KNR Maintenance Limited | Construction | 2023 |
| KNT Properties Ltd | Real estate | 2021 |
| Knuckleheads Barbershop Ltd | Other services | 2025 |
| Knucks Ltd | Financial services | 2016 |
| KNV Ltd | Wholesale & retail | 2018 |
| Knvt Ltd | Professional & scientific | 2016 |
| KO Coaches Ltd | Transport & logistics | 2018 |
| Koalava Ltd | Transport & logistics | 2020 |
| Koben Consulting Limited | Professional & scientific | 2024 |
| Kobilren Ltd | Wholesale & retail | 2025 |
| Kobri Ltd | Information & communication | 2019 |
| Kocaer Steel UK Limited | Wholesale & retail | 2013 |
| Kocho Group Holdings Limited | Financial services | 2021 |
| Kocho Group Limited | Information & communication | 2001 |
| Kocho Holdings Limited | Information & communication | 2012 |
| Kocho Midco Limited | Financial services | 2021 |
| Kode Consultancy Limited | Administrative & support | 2017 |
| Kodee Stores Ltd | Wholesale & retail | 2025 |
| Kodensha Limited | Professional & scientific | 2005 |
| Kodo Cardiff Limited | Hospitality | 2025 |
| Kodur Fintech Limited | Financial services | 2020 |
| Kody Properties Limited | Real estate | 2025 |
| Kognitiv UK Ltd | Professional & scientific | 1960 |
| Kohong SIN Ltd | Wholesale & retail | 2025 |
| KOI Talent Ltd | Professional & scientific | 2025 |
| Koine Construction Limited | Construction | 2026 |
| Koko Trade Ltd | Wholesale & retail | 2025 |
| Kokoa UK Limited | Manufacturing | 2017 |
| Kokobase International Trading Ltd | Wholesale & retail | 2019 |
| Kokoriko Limited | Hospitality | 2020 |
| Kokoro Arts Ltd | Education | 2019 |
| Kokuun Trade Ltd | Wholesale & retail | 2024 |
| Kola International Trading Company Limited | Wholesale & retail | 2026 |
| Kolaki Recruiting Ltd | Administrative & support | 2021 |
| Kolcom Ltd | Wholesale & retail | 2025 |
| Kolex Bateman London Limited | Wholesale & retail | 2020 |
| Kolidelka for Mobile Devices Trading Ltd | Wholesale & retail | 2025 |
| Kollis CAD Limited | Administrative & support | 2007 |
| Kollpa Recruits Ltd | Administrative & support | 2022 |
| Kolme Roofing and Building Ltd | Construction | 2025 |
| Kolo Finance Limited | Information & communication | 2024 |
| Kolopori Services Ltd | Administrative & support | 2021 |
| Kolyaland Ltd | Wholesale & retail | 2025 |
| Komix Technologies Limited | Information & communication | 2024 |
| Komodo Creative Limited | Information & communication | 2026 |
| Kompin Partners PC | | 2020 |
| Konako Ltd | Wholesale & retail | 2026 |
| Konaq Restaurant Ltd | Hospitality | 2025 |
| Koncept 365 Limited | Professional & scientific | 2013 |
| Koncept Consultancy Limited | Information & communication | 2019 |
| Koncept Design Ltd | Extraterritorial | 2013 |
| Kondov Limited | Construction | 2017 |