| Katie Close Management Limited | Administrative & support | 2010 |
| Katie FOX Estate Agents Ltd | Extraterritorial | 2022 |
| Katie Lord Limited | Other services | 2023 |
| Katie's Store Ltd | Wholesale & retail | 2020 |
| Kautella Soragi Limited | Education | 2025 |
| Kazedek Ltd | Administrative & support | 2026 |
| KB Mobilecare Ltd | Health & social care | 2017 |
| Kbirch Holdings Ltd | Arts & recreation | 2026 |
| Kbond Consulting Ltd | Real estate | 2013 |
| KBS South West Limited | Professional & scientific | 2025 |
| KC Carpets & Flooring Limited | Wholesale & retail | 2002 |
| KC Transport Haulage Ltd | Transport & logistics | 2025 |
| KCK Bricklaying Ltd | Construction | 2025 |
| Kcontent Ltd | Information & communication | 2023 |
| Kcopse Services Limited | Professional & scientific | 2025 |
| Kcseven Ltd | Construction | 2020 |
| Kctg FA Limited | Financial services | 2018 |
| Kctg Japan Holdings Ltd. | Financial services | 2015 |
| Kcthepilot Ltd | Information & communication | 2020 |
| KD Painting & Decorating Ltd | Construction | 2023 |
| Kddm Ltd | Manufacturing | 2022 |
| KDL Services Ltd | Information & communication | 2019 |
| Kdnt Limited | Wholesale & retail | 2015 |
| KDW Property Services Ltd | Construction | 2018 |
| Keable Consulting Limited | Construction | 2025 |
| Keep on Roaming Ltd | Information & communication | 2023 |
| Kelcarla Limited | Real estate | 1976 |
| Kellclair Limited | Financial services | 2021 |
| Kellentay Beers Ltd | Manufacturing | 2014 |
| Kelly Bunn Ltd | Professional & scientific | 2021 |
| Kellys Homes Limited | Real estate | 2017 |
| Kelvin & Watt Ltd | Construction | 2021 |
| Kelvin Woodward Expert Limited | Professional & scientific | 2019 |
| Kempsey Lodge RTM Company Limited | Households | 2020 |
| Kendall Copywriting Ltd | Professional & scientific | 2008 |
| Keniston Group Ltd | Wholesale & retail | 2020 |
| Kenix and Merrifield Publishers Ltd | Information & communication | 2024 |
| Kenley Trading | Real estate | 1999 |
| Kennedy's (Southern) Ltd | Construction | 2008 |
| Kennedybaguga Ltd | Wholesale & retail | 2025 |
| Kennington 16 Limited | Other services | 2019 |
| Kenprop Ltd | Real estate | 2023 |
| Kensington International Marketing Company Limited | Administrative & support | 1999 |
| Kent Homes (Bournemouth) Ltd | Real estate | 2019 |
| Kenton Retail LLP | | 2006 |
| Kenvix Trading Ltd | Wholesale & retail | 2026 |
| Keraziva Limited | Wholesale & retail | 2025 |
| Kerbi Ltd | Manufacturing | 2025 |
| Kershaw Establishments Ltd | Information & communication | 2023 |
| Kesimi Ltd | Other services | 2026 |
| Kester Trading Company Limited | Wholesale & retail | 2023 |
| Kesteron Limited | Administrative & support | 2011 |
| Kestrel Ophthalmics Limited | Wholesale & retail | 2001 |
| Kestrel Retail Limited | Wholesale & retail | 2025 |
| Kevin Holborn Electrical Limited | Manufacturing | 2004 |
| Kevitrans Limited | Manufacturing | 2015 |
| Kevlin CNC Services Limited | Manufacturing | 2010 |
| Kewarra Publishing Limited | Professional & scientific | 2011 |
| Key Business Finance Ltd | Financial services | 2024 |
| Key Business Professions Ltd | Financial services | 2024 |
| Key Care Properties Limited | Construction | 2012 |
| Key Estates Development Limited | Construction | 1999 |
| Key Pneumatics Holdings Ltd | Manufacturing | 2024 |
| Key Pneumatics Limited | Manufacturing | 1994 |
| Key Solutions Dorset Ltd | Construction | 2010 |
| Keycad Ltd | Professional & scientific | 2023 |
| Keyshores Internet Ltd | Wholesale & retail | 2020 |
| Keystone Civil Engineering Ltd | Construction | 2016 |
| Keytek Group Limited | Professional & scientific | 2020 |
| Keytek UK Limited | Administrative & support | 2005 |
| KF Dental Practice Ltd | Health & social care | 2024 |
| KF Finance Limited | Professional & scientific | 2013 |
| Kffinish Limited | Manufacturing | 2021 |
| KFH Investments Limited | Real estate | 2016 |
| KFK VW Ltd | Wholesale & retail | 2012 |
| Kgal Consulting Engineers Ltd | Professional & scientific | 1998 |
| Kgbm Limited | Hospitality | 2022 |
| KGE Store Limited | Wholesale & retail | 2026 |
| Khadija Mushtaq Ltd | Wholesale & retail | 2023 |
| Khamis Alshabibi Limited | Wholesale & retail | 2025 |
| Khan Worldwide Holdings Ltd | Real estate | 2020 |
| Khanglobally Ltd | Administrative & support | 2024 |
| Khaya Care Solutions Ltd | Health & social care | 2024 |
| KHD Hairdressing Limited | Other services | 2025 |
| KHD Services Ltd | Administrative & support | 2023 |
| KHE Properties Limited | Real estate | 2016 |
| Khilan London Ltd | Wholesale & retail | 2024 |
| Khoja.Pk Ltd | Wholesale & retail | 2024 |
| KHR Design Ltd | Professional & scientific | 2016 |
| Kibin Solutions Limited | Information & communication | 2020 |
| Kiboko Limited | Manufacturing | 2023 |
| Kicards Ltd | Wholesale & retail | 2025 |
| Kicards Luxe Ltd | Wholesale & retail | 2026 |
| Kicking Mule Drinks Ltd | Manufacturing | 2023 |
| Kickstart Coffee Community Interest Company | Wholesale & retail | 2020 |
| Kickstart Learning With Kerry Ltd | Education | 2017 |
| Kiddose Ltd | Manufacturing | 2025 |
| Kids Barn Studios Ltd | Arts & recreation | 2025 |
| Kids Love Nature (Lymington) Ltd | Education | 2006 |
| Kids Love Nature (Lytchett) Ltd | Education | 2018 |