| JTX Properties Ltd | Real estate | 2025 |
| Jubilant Rainbow Ltd | Wholesale & retail | 2023 |
| Jubilee Controls Limited | Administrative & support | 2002 |
| Jubilee Rentals Ltd | Real estate | 2025 |
| Judson Property Limited | Real estate | 2023 |
| Julia Karen Limited | Wholesale & retail | 2025 |
| Julio's New Fashion Ltd | Other services | 2022 |
| Jumbo Contracting Limited | Information & communication | 2005 |
| Jumbo IT Services Limited | Information & communication | 2011 |
| Jumbopizza Limited | Hospitality | 2026 |
| Jumping Over Wall Ltd | Wholesale & retail | 2025 |
| Junction 13 Used Car Sales Ltd | Wholesale & retail | 2025 |
| Junhao International Trade Co., Ltd | Wholesale & retail | 2025 |
| Just ADD Products Ltd | Wholesale & retail | 2025 |
| Just Energy Limited | Construction | 2023 |
| Justfixroofing Ltd | Construction | 2026 |
| Justonia Holdings Ltd | Real estate | 2026 |
| JV Industries Ltd | Administrative & support | 2025 |
| JW Commercial Systems Limited | Construction | 2024 |
| JW Mystic Creations Co., Ltd | Wholesale & retail | 2024 |
| JW Property Care Ltd | Construction | 2015 |
| JW Roofline Installations Ltd | Construction | 2023 |
| JWA Rapid Design and Realisation Limited | Professional & scientific | 2017 |
| JWC Transport Limited | Transport & logistics | 2011 |
| Jwdm 2018 Limited | Hospitality | 2025 |
| JWE Construction Limited | Construction | 2023 |
| JXB Joint Integrity Ltd | Other services | 2023 |
| K & S Care Solutions Ltd. | Administrative & support | 2018 |
| K and E Holdings Ltd | Real estate | 2015 |
| K Bradbury Plastering Ltd | Construction | 2021 |
| K G Building Limited | Construction | 2006 |
| K Jones Fabrications Ltd | Manufacturing | 2015 |
| K Jordan Installations Ltd | Manufacturing | 2023 |
| K M Motors Services Ltd | Wholesale & retail | 2024 |
| K Pole Studios Limited | Arts & recreation | 2024 |
| K R Commercial Services Limited | Construction | 2015 |
| K R Group Limited | Financial services | 2016 |
| K&M Import and Export Co., Ltd | Wholesale & retail | 2025 |
| K.B.A. Investments Limited | Wholesale & retail | 1997 |
| K2 Automation Ltd. | Wholesale & retail | 2020 |
| K4 MWH Ltd. | Administrative & support | 2010 |
| K9 Hydro Care Ltd | Professional & scientific | 2022 |
| Kabmet Dynamics Limited | Wholesale & retail | 2025 |
| Kacki Medical Ltd | Health & social care | 2016 |
| Kadari Limited | Other services | 1995 |
| Kaisen Machinery Limited | Manufacturing | 2023 |
| Kaisers Consultants Ltd | Professional & scientific | 2026 |
| Kaisery Industry Limited | Extraterritorial | 2018 |
| Kaitakare Limited | Hospitality | 2002 |
| Kaiyang International Trade Co., Ltd | Wholesale & retail | 2024 |
| Kalacera Ltd | Arts & recreation | 2023 |
| Kalam's Kitchen Ltd | Hospitality | 2025 |
| Kalating London Ltd | Wholesale & retail | 2014 |
| Kaleidoscope Group of Companies Ltd Ltd | Information & communication | 2023 |
| Kalonji Limited | Public administration | 2023 |
| Kaminski Corporate Limited | Transport & logistics | 2012 |
| Kamoosy Ltd | Health & social care | 2022 |
| Kamtech Fasteners Ltd | Wholesale & retail | 2015 |
| Kanddutilities Limited | Administrative & support | 2025 |
| Kangberry Tech Limited | Wholesale & retail | 2023 |
| Kangxin (UK) Limited | Health & social care | 2004 |
| Kaniv Consultancy Limited | Health & social care | 2021 |
| Kanoka Ltd | Professional & scientific | 2025 |
| Kanpur Ltd | Real estate | 2025 |
| Kansingten Ltd | Wholesale & retail | 2025 |
| Kanvas Medical Group Ltd | Health & social care | 2022 |
| Karandashik Ltd | Administrative & support | 2024 |
| Karens Estates Ltd | Real estate | 2008 |
| Karjanwill Limited | Real estate | 1998 |
| Karl William Walker Ltd | Wholesale & retail | 2026 |
| Karnecs Property Ltd | Real estate | 2023 |
| Karntek Ltd | Public administration | 2017 |
| Kasen International Group Limited | Manufacturing | 2023 |
| Kassel Group Ltd | Extraterritorial | 2010 |
| Kassi Retail Ltd | Wholesale & retail | 2023 |
| Kate Robson Sports Consultancy Limited | Arts & recreation | 2022 |
| Kate's Clothing Ltd | Wholesale & retail | 2005 |
| Katharine House Retail Limited | Wholesale & retail | 2000 |
| Katie’S Flower House Ltd | Arts & recreation | 2025 |
| Katy Metcalfe Limited | Professional & scientific | 2020 |
| Kaur Locums Limited | Health & social care | 2022 |
| Kavandata Ltd | Information & communication | 2021 |
| Kayeldee Ltd | Other services | 2026 |
| Kayleigh Dobson Consulting Ltd | Administrative & support | 2026 |
| Kayne Properties Two Limited | Real estate | 2019 |
| Kayne Properties UK Limited | Real estate | 2015 |
| Kays Social Care Limited | Health & social care | 2016 |
| KB55 Limited | Education | 2017 |
| KBC Healthcare Consultants Ltd | Extraterritorial | 2024 |
| KBS Trading Company Limited | Wholesale & retail | 2025 |
| KC Advanced Solutions Limited | Health & social care | 2025 |
| KC Site Management and Consulting Ltd | Professional & scientific | 2021 |
| KC UK United Ltd | Wholesale & retail | 2025 |
| KD Contour Medical Aesthetics Ltd | Other services | 2024 |
| KD Law (Solicitors) Limited | Professional & scientific | 2014 |
| KDF Group Ltd | Hospitality | 2026 |
| KDN Services Limited | Construction | 2026 |
| KDS Orthopaedics Limited | Health & social care | 2012 |
| Keay Maintenance Limited | Administrative & support | 2019 |
| Keiran Fine Trades Limited | Wholesale & retail | 2025 |