| Keynest Management and Investments Limited | Professional & scientific | 2025 |
| Keyprint Limited | Manufacturing | 1982 |
| Keystone Business Enterprise Limited | Real estate | 2024 |
| Keystone Interiors Limited | Construction | 2020 |
| Keystone Residentials Limited | Real estate | 2023 |
| KFP Property Limited | Real estate | 2025 |
| KGN Imports & Supply Ltd | Wholesale & retail | 2025 |
| KGN Trading London Ltd | Wholesale & retail | 2024 |
| KGP Laboratories (UK) Limited | Wholesale & retail | 2004 |
| KGR Developments Limited | Construction | 2022 |
| KH Psychology Limited | Health & social care | 2011 |
| Khaira Freehold Ltd | Real estate | 2025 |
| Khaira Homes Ltd | Hospitality | 2022 |
| Khamb Ltd | Real estate | 2024 |
| Khandhar Ltd | Construction | 2022 |
| Khanna London Limited | Real estate | 2021 |
| KHANSTRUCTION786 Ltd | Construction | 2025 |
| Khatra Investments Limited | Real estate | 2025 |
| Khawaja Group Limited | Manufacturing | 2025 |
| Khayam Hafeez Ltd | Wholesale & retail | 2025 |
| Khehra Homes Limited | Real estate | 2025 |
| KHK Ltd | Real estate | 2021 |
| Khosa Solutions Limited | Real estate | 2024 |
| KHR Development Ltd | Construction | 2026 |
| Khurana Grocers Store Ltd | Wholesale & retail | 2018 |
| Khushbani Group Ltd | Wholesale & retail | 2023 |
| Khushdeep Singh Ltd | Construction | 2023 |
| KIA Galaxy Limited | Construction | 2016 |
| KIA ORA Support Services Ltd | Health & social care | 2024 |
| Kian Ventures Ltd | Wholesale & retail | 2025 |
| Kiara Lounge Limited | Hospitality | 2020 |
| Kickcore Ltd | Arts & recreation | 2025 |
| KID Land Limited | Wholesale & retail | 2015 |
| Kiesse Ltd | Health & social care | 2023 |
| KIF Car Wash Ltd | Other services | 2011 |
| Killinchy Aerospace Holdings Limited | Manufacturing | 1965 |
| Kimbuild Construction Ltd | Construction | 2024 |
| Kind Air Ltd | Wholesale & retail | 2017 |
| Kinellan Court Beaconsfield (1999) Limited | Real estate | 1999 |
| Kinellan Court Residents Association (Beaconsfield) Limited | Real estate | 1961 |
| Kinetics Process Consulting UK Limited | Professional & scientific | 2019 |
| King Cobra Duct Rods Limited | Professional & scientific | 1990 |
| Kingdom Commodities Limited | Wholesale & retail | 2024 |
| Kingdom Group Holdings Ltd | Financial services | 2025 |
| Kingdom Metal Recycling Limited | Wholesale & retail | 2025 |
| Kingdom Recycling Limited | Water & waste | 2025 |
| Kingfisher Court Management Company (High Wycombe) Limited | Real estate | 1989 |
| Kingfisher Printing Ltd | Manufacturing | 2014 |
| Kings Automotive Ltd | Wholesale & retail | 2024 |
| Kings Court (South Harrow) Limited | Households | 1996 |
| Kingsbury Desire Limited | Hospitality | 2019 |
| Kingsley Opticians Limited | Wholesale & retail | 1990 |
| Kingsmead House (Management) Limited | Real estate | 1993 |
| Kingstable Street Flats RES. (Eton) Limited | Real estate | 1994 |
| Kingswood Smith Limited | Professional & scientific | 2019 |
| Kingz Properties Limited | Hospitality | 2021 |
| Kinseed Limited | Information & communication | 2013 |
| Kinseed Swiftcare Limited | Information & communication | 2017 |
| Kinsmead Homes Development Limited | Construction | 2024 |
| Kira Build Ltd | Construction | 2023 |
| Kirium Consulting Limited | Professional & scientific | 2011 |
| Kirkstall Lodge Limited | Health & social care | 2003 |
| Kirkwallacealderman Limited | Administrative & support | 2009 |
| Kirpa Builders Limited | Construction | 2022 |
| Kirsty Collins Coaching Ltd | Administrative & support | 2023 |
| Kirtech Ltd | Information & communication | 2015 |
| KIS Autocentres Ltd | Wholesale & retail | 2022 |
| Kishan Investments Limited | Real estate | 2020 |
| Kitchen Supplier Ltd | Construction | 2018 |
| Kittycathome Ltd | Information & communication | 2025 |
| Kixx Uxbridge Limited | Arts & recreation | 2019 |
| Kiyaanshx Ltd | Hospitality | 2025 |
| Kizzy Dhaliwal Productions Limited | Information & communication | 2017 |
| KJ Autoparts Limited | Wholesale & retail | 2023 |
| KJH Tech Ltd | Wholesale & retail | 2020 |
| Kjlr Transport Ltd | Transport & logistics | 2025 |
| KK Convenience Stores Limited | Wholesale & retail | 2010 |
| KK London Developments Ltd | Real estate | 2021 |
| Kk&B Limited | Wholesale & retail | 2024 |
| Kkalmm Logistics Ltd | Transport & logistics | 2022 |
| Kkrb Property Management Ltd | Real estate | 2024 |
| Kkvh Limited | Professional & scientific | 2015 |
| KL General Services Limited | Wholesale & retail | 2022 |
| KL Kitchen Ltd | Hospitality | 2026 |
| Klaguda Limited | Administrative & support | 2022 |
| Klassic Properties Limited | Real estate | 2023 |
| Klaudia Binder Limited | Health & social care | 2023 |
| Klear Root Ltd | Manufacturing | 2026 |
| Kleio Collection Ltd | Wholesale & retail | 2026 |
| Klis Joinery & Carpentry Ltd | Construction | 2017 |
| KM Automotive Europe Ltd | Wholesale & retail | 2019 |
| KM Door 2 Door Ltd | Transport & logistics | 2018 |
| KMJ Consultancy Ltd | Professional & scientific | 2025 |
| KMP Properties Ltd | Real estate | 2020 |
| Knauf Ceiling Solutions Limited | Manufacturing | 1995 |
| Knight Property Estates Ltd | Construction | 2018 |
| Knightsbridge Interiors Limited | Wholesale & retail | 2022 |
| Knightsbridge Prime Development Ltd | Construction | 2024 |
| Knightsfall Limited | Transport & logistics | 2023 |
| KNK Collections Ltd | Wholesale & retail | 2025 |