| Kiwitoucan Limited | Real estate | 2025 |
| KJ Properties (MK) LLP | | 2023 |
| KJB Property Limited | Real estate | 2016 |
| Kjbmk Limited | Administrative & support | 2025 |
| KJC Entertainment Ltd | Information & communication | 2024 |
| KJJ Designs Ltd | Professional & scientific | 2019 |
| KJP Financial Services Ltd | Financial services | 2026 |
| KJS Veterinary Limited | Professional & scientific | 2018 |
| KJT Recruitment Ltd | Administrative & support | 2023 |
| KJW Drylining Limited | Construction | 2006 |
| KJW Properties Limited | Real estate | 2016 |
| Kjwellbeing Services Limited | Health & social care | 2022 |
| KK Property Rentals Limited | Real estate | 2025 |
| KKC Kart Components Ltd | Administrative & support | 2008 |
| KKH Property Limited | Real estate | 2020 |
| KKR Consultancy Limited | Health & social care | 2018 |
| KLA Group Limited | Financial services | 2022 |
| Klara & Co Ltd | Arts & recreation | 2021 |
| Klarbyte Labs Ltd | Wholesale & retail | 2026 |
| Kld.Installations Ltd | Construction | 2024 |
| Kleanmk Ltd | Administrative & support | 2026 |
| Kleen TEK Services Limited | Administrative & support | 2025 |
| Kler Associates Limited | Professional & scientific | 2004 |
| Kleva Carpentry Limited | Construction | 2022 |
| Klever Bros Ltd | Professional & scientific | 2003 |
| Klever Motion Limited | Information & communication | 2020 |
| Klex Trans Ltd | Transport & logistics | 2023 |
| KLF Construction Limited | Construction | 2010 |
| KLG Distribution Limited | Wholesale & retail | 2025 |
| Klick Logistics Group Ltd | Transport & logistics | 2023 |
| KLM Resourcing Limited | Administrative & support | 2016 |
| Klmb Services Limited | Real estate | 2025 |
| Klober Limited | Wholesale & retail | 1985 |
| Kloeber International Trading Limited | Professional & scientific | 2006 |
| Klrcustomworks Ltd | Wholesale & retail | 2020 |
| Kluthe UK Ltd | Wholesale & retail | 2001 |
| KLW Beauty Limited | Other services | 2015 |
| KLY Lees Limited | Hospitality | 2020 |
| Klymate Ltd | Information & communication | 2023 |
| KM (MK) Ltd | Professional & scientific | 2013 |
| KM D&B Limited | Construction | 2025 |
| KM International Limited | Professional & scientific | 2022 |
| KM Telemarketing Ltd | Professional & scientific | 2014 |
| KM47 Consulting Limited | Professional & scientific | 2023 |
| KMA Management Ltd | Professional & scientific | 2013 |
| Kmarketing Ltd | Professional & scientific | 2024 |
| Kmateev 89 Ltd | Transport & logistics | 2026 |
| Kmatt Property Management Ltd | Real estate | 2020 |
| KMC Automotive Ltd | Administrative & support | 2017 |
| KMH Fibre Ltd | Construction | 2023 |
| KMI Services Ltd | Administrative & support | 2025 |
| Kmjf LLP | | 2024 |
| Kmkxl Ltd | Information & communication | 2025 |
| Kmpc Ltd | Real estate | 2020 |
| Kmsd Ltd | Manufacturing | 2021 |
| Kmsquare Homes Limited | Real estate | 2025 |
| Kmtr Properties Ltd | Other services | 2020 |
| Knana Medical Ltd | Health & social care | 2022 |
| Knaresborough Water Ltd | Water & waste | 2025 |
| Knead That Dough Ltd | Professional & scientific | 2022 |
| Knee Motion Sensor Ltd | Other services | 2024 |
| Knight Dental Hygiene Group Ltd | Health & social care | 2024 |
| Knight International (UK) Limited | Real estate | 2005 |
| Knight-Racer Performance & Styling Limited | Manufacturing | 2015 |
| Knightbell Limited | Energy | 1989 |
| Knights MK Limited | Real estate | 2014 |
| Knights Real Estate Ltd | Real estate | 2025 |
| Knightserve Consultancy Limited | Real estate | 2011 |
| Kniva Limited | Information & communication | 2016 |
| KNK Flooring Ltd | Construction | 2025 |
| Knobwerks Limited | Extraterritorial | 2014 |
| Knollys Road Developments Ltd | Construction | 2026 |
| Knourish Beauty Ltd | Other services | 2021 |
| Know Howe Solutions Ltd | Construction | 2021 |
| Knowledge Merchandising Ltd | Administrative & support | 2021 |
| Knowledge Oral Health Care Ltd | Health & social care | 2015 |
| Knowledge Schemes Ltd | Education | 2024 |
| Knowledge Stream Ltd | Information & communication | 2021 |
| Knowles Property Investments Ltd | Real estate | 2018 |
| Knowlesbuildingservice Limited | Construction | 2023 |
| Knowlhill Property Management Company Limited | Extraterritorial | 2004 |
| Knox Management Limited | Construction | 2016 |
| Koadat Ltd | Administrative & support | 2022 |
| Koak Services Limited | Other services | 2018 |
| KOB Consultancy Limited | Other services | 2014 |
| Kocho Serenity Limited | Health & social care | 2026 |
| Koda Commerce Ltd | Wholesale & retail | 2026 |
| Kodacubes Limited | Information & communication | 2015 |
| Kofo Wholefoods Ltd | Manufacturing | 2018 |
| Kohai Productions Ltd | Information & communication | 2025 |
| Koinonia U.K. Ltd | Other services | 2023 |
| Kokeyo Ltd | Health & social care | 2019 |
| Kokoso Limited | Professional & scientific | 2013 |
| Koleth Ltd | Extraterritorial | 2011 |
| Koli Construction & Scaffolding Ltd | Construction | 2024 |
| Kolkata Restaurant Ltd | Hospitality | 2021 |
| Kolsat Consulting Limited | Professional & scientific | 2012 |
| Kommuters.Com Limited | Information & communication | 2025 |
| Kompan Limited | Construction | 1983 |
| Koncept Hair and Beauty Ltd | Other services | 2019 |