| Kaizen Consultants Holdings Limited | Financial services | 2020 |
| Kaizen Recycling Limited | Professional & scientific | 2007 |
| Kaizen Recycling Limited Liability Partnership | | 2006 |
| Kaizen Recycling Technology Ltd | Administrative & support | 2014 |
| Kaleidoscope Framing Limited | Manufacturing | 2006 |
| Kalmar Limited | Manufacturing | 2015 |
| Kamz Construction Ltd | Construction | 2019 |
| Kanai Care Limited | Hospitality | 2022 |
| Kaneda Associates Limited | Professional & scientific | 2019 |
| Kanu House Ltd | Real estate | 2024 |
| Kanu Poké Ltd | Hospitality | 2021 |
| Kape Property Management Ltd | Households | 2021 |
| Kare Ferdinand Ltd | Other services | 2023 |
| Karen Mcquade.Com Limited | Extraterritorial | 2007 |
| Karicare Limited | Health & social care | 2022 |
| Kasen Cranes Limited | Manufacturing | 2008 |
| Katalyst Origin Limited | Professional & scientific | 2025 |
| Katies Kids Holdings Limited | Financial services | 2025 |
| Katz Holdings Ltd | Real estate | 2025 |
| KAY & KAY Property Limited | Real estate | 2022 |
| Kayqs Ltd | Professional & scientific | 2022 |
| KB Legal Support Ltd | Professional & scientific | 2023 |
| KC IT & Business Services Ltd | Information & communication | 2024 |
| KD Infrastructure Solutions Ltd | Information & communication | 2023 |
| KDM Civil Engineering Ltd | Construction | 2026 |
| KDM Plant Hire Ltd | Construction | 2023 |
| Kedleston Court (Derby) Management Company Limited | Households | 1987 |
| Keeping IT Professionals Limited | Information & communication | 2020 |
| Keepnet Limited | Information & communication | 1998 |
| Keith Evans Machinery Limited | Wholesale & retail | 2023 |
| Keith Phillips and Sons Limited | Construction | 2008 |
| Keith Winter Limited | Professional & scientific | 2011 |
| Kel-Mar Ltd | Other services | 2015 |
| Kelland Homes Limited | Real estate | 2025 |
| Kelowna Bears Limited | Water & waste | 2019 |
| Kelpi Limited | Professional & scientific | 2016 |
| KEN Law Limited | Financial services | 2022 |
| Kenley Hall Construction Limited | Construction | 2023 |
| Kennedy Enterprises Limited | Information & communication | 2000 |
| Kennedy House Services Limited | Professional & scientific | 2000 |
| Kennelhub Ltd | Agriculture & fishing | 2025 |
| Kenning Illustration & Creative Design Ltd | Arts & recreation | 2009 |
| Kennington Park Square RTM Company Limited | Households | 2019 |
| Kenny's Kards Ltd | Wholesale & retail | 2024 |
| Kensington Place (Northampton) Residents Association Limited | Households | 2003 |
| Kenwood PI Holdings Limited | Financial services | 2023 |
| Kernow Gate (Saltash) Management Company Limited | Households | 2003 |
| Keti Properties Limited | Households | 2025 |
| Key & Key Limited | Financial services | 2017 |
| Key 3 Media Limited | Professional & scientific | 2011 |
| Keyland Polymer UV Resins, Ltd | Manufacturing | 2006 |
| Keystone AI App Ltd | Information & communication | 2025 |
| KF Hereford & Worcester Ltd | Real estate | 2024 |
| KF Residential Birmingham Ltd | Real estate | 2024 |
| KF West Midlands Ltd | Real estate | 2021 |
| Kfood.Cook Ltd | Manufacturing | 2025 |
| Khafaji Property Ltd | Real estate | 2023 |
| Khaos AI Ltd | Information & communication | 2026 |
| Khitan Ltd | Other services | 2009 |
| Khodal Retail Ltd | Wholesale & retail | 2026 |
| Khush Property Limited | Real estate | 2025 |
| Kick Associates Limited | Information & communication | 2018 |
| Kidz Connect Psychology Ltd | Health & social care | 2023 |
| Kieran Pinches Fcca CTA Ltd | Professional & scientific | 2024 |
| Killeen Decorators Ltd | Construction | 2025 |
| Kilospec Limited | Information & communication | 2007 |
| Kind of Blue Consulting Limited | Professional & scientific | 2007 |
| Kinetic Health Partners Ltd | Administrative & support | 2026 |
| Kingfisher Apartments (Kirby Muxloe) Limited | Real estate | 2020 |
| Kingfisher Planning Shrewsbury Limited | Professional & scientific | 2011 |
| Kings Court (Church Stretton) Ltd | Households | 1983 |
| Kings Norton Bowling Club Limited(The) | Hospitality | 1936 |
| Kingsland Consultants Limited | Professional & scientific | 2012 |
| Kingsland Designs Limited | Other services | 2012 |
| Kingsland Estates U.K. Limited | Real estate | 2000 |
| Kingsland Meadow Property Limited | Real estate | 2013 |
| Kingsland Studio Ltd | Professional & scientific | 2005 |
| Kingswood Court (Wigston) Freeholders Limited | Real estate | 2005 |
| Kingswood Court (Wigston) Management Company Limited | Real estate | 1988 |
| Kingswood Leisure Limited | Wholesale & retail | 1974 |
| Kinnersley House Residents Association Limited | Households | 2005 |
| Kinnerton Consulting Ltd | Professional & scientific | 2024 |
| Kinnerton Way Management Company Limited | Households | 2002 |
| Kinship Inheritance Limited | Professional & scientific | 2020 |
| Kinship OCA Property Ltd | Construction | 2025 |
| Kinstone Properties Limited | Construction | 2025 |
| Kinton Farm Storage Limited | Agriculture & fishing | 1998 |
| Kiray Consultants Limited | Extraterritorial | 2019 |
| Kiszls Limited | Financial services | 2021 |
| Kitchen and Bedroom Revivals Limited | Wholesale & retail | 2016 |
| Kitchen Innovations Limited | Wholesale & retail | 2018 |
| Kitts Green Management (36-58 Goldstar Way) Ltd | Households | 1992 |
| Kitts Green Management (Plots 227-241) Limited | Households | 1992 |
| Kitts Green Management Limited | Households | 1990 |
| KJ Operator Support Limited | Construction | 2020 |
| KJ Trading and Investments Ltd | Real estate | 2018 |
| Kj-Itc Ltd | Information & communication | 2022 |
| Kjokken Ltd | Professional & scientific | 2018 |
| KKS One Ltd | Wholesale & retail | 2020 |
| Kleinlegal Limited | Professional & scientific | 2020 |