| Kaifa Restaurant Ltd | Hospitality | 2025 |
| KAIROS7 Building Services Ltd | Construction | 2017 |
| Kaizapp Limited | Information & communication | 2014 |
| Kaizen Learning Company Ltd | Education | 2026 |
| Kakaw House Limited | Financial services | 2026 |
| Kale Training Limited | Education | 2022 |
| Kalegate Limited | Real estate | 2016 |
| Kali Marketing Ltd | Administrative & support | 2020 |
| Kapwealth Limited | Financial services | 2012 |
| Kardiokids (UK) Ltd. | Arts & recreation | 2016 |
| Karenjeet Bains Limited | Education | 2022 |
| Karl Gray Ltd | Wholesale & retail | 2020 |
| Karon Ltd | Other services | 2020 |
| Karus Estates Ltd | Real estate | 2025 |
| Katanya LLP | | 2011 |
| Katanya Ventures Limited | Information & communication | 2022 |
| Kate Petty Limited | Arts & recreation | 2019 |
| Kathryn Cearns Consultancy Limited | Professional & scientific | 2014 |
| Katy's Theatrical Productions Limited | Arts & recreation | 2019 |
| Kavineer Limited | Real estate | 2023 |
| Kawp Holdings Ltd | Transport & logistics | 2022 |
| Kaya K (Horns Road) 8.2 Limited | Construction | 2024 |
| Kaya Landmarks Limited | Construction | 2020 |
| Kayalvijay Ltd | Health & social care | 2023 |
| Kaykay Technology Services Limited | Information & communication | 2011 |
| KAZ Medical Ltd. | Administrative & support | 2019 |
| KB Design Consultants Ltd | Professional & scientific | 2020 |
| Kbkrraft Ltd | Other services | 2024 |
| KC Future Consulting Ltd | Administrative & support | 2014 |
| Keash Properties (Whetstone) Limited | Financial services | 2025 |
| Kebab City Ltd | Hospitality | 2020 |
| Kebab Expres Ltd | Hospitality | 2019 |
| Kebab Prophecy Ltd | Hospitality | 2022 |
| Kelburn Engineering Limited | Manufacturing | 1999 |
| Kelburn Limited | Real estate | 2012 |
| Kelly TEH Ltd | Arts & recreation | 2026 |
| Kendal Office Contracts Limited | Construction | 1980 |
| Kenima Limited | Administrative & support | 2024 |
| Kenneth Anim Ltd | Administrative & support | 2018 |
| Kent Central Ambulance Service Ltd | Health & social care | 2017 |
| Kerneltech Limited | Information & communication | 2011 |
| Kesgin Properties Ltd | Real estate | 2024 |
| Keshvi Ltd | Administrative & support | 2025 |
| Keswick European Holdings Limited | Financial services | 2013 |
| Keswick Food Services Group Ltd | Transport & logistics | 1994 |
| Keswick International Holdings Ltd | Financial services | 2014 |
| KEW Square Developments Limited | Real estate | 2019 |
| Key Logo Limited | Administrative & support | 1999 |
| Keydis Limited | Extraterritorial | 2000 |
| Keyholder Estates Limited | Real estate | 2024 |
| Keystone Consultants (London) Ltd | Administrative & support | 2017 |
| KG Coffee E14 Ltd | Hospitality | 2024 |
| KG Coffee Ltd | Hospitality | 2020 |
| KG Coffee Ongar Ltd | Hospitality | 2024 |
| Khan Emporium Limited | Wholesale & retail | 2024 |
| Khidmat Exeter Limited | Hospitality | 2025 |
| Khidmat Holding Limited | Financial services | 2025 |
| KHM Property Ltd | Households | 2020 |
| Khost Ltd | Hospitality | 2021 |
| Khubsoorat-Uk Limited | Wholesale & retail | 1999 |
| Kiani Property Investments Limited | Real estate | 2003 |
| Kickabout Productions Limited | Information & communication | 2001 |
| Kids Dental Core Ltd | Health & social care | 2026 |
| Kids Dental Kaur Ltd | Health & social care | 2026 |
| Kids in Crisis | Other services | 2011 |
| KIDS2TEENS | Arts & recreation | 2008 |
| Kieran Knight Consulting Limited | Professional & scientific | 2007 |
| Kieran Salawu Consultancy Ltd | Administrative & support | 2025 |
| Killick Maintenance Services Limited | Construction | 2025 |
| Kimberley Real Estate Limited | Real estate | 2016 |
| Kinab Properties Limited | Real estate | 2023 |
| Kinetika Electrical Contractors Limited | Construction | 2008 |
| Kinetyx Limited | Professional & scientific | 2026 |
| King of Kings Development Limited | Construction | 2017 |
| Kingdom Care Children Home Ltd | Health & social care | 2022 |
| Kings Oak Court (Reading) RTM Company Ltd | Households | 2011 |
| Kingshill News Limited | Wholesale & retail | 2009 |
| Kingsland Care Limited | Health & social care | 2022 |
| Kingsland Empire Ltd | Real estate | 2016 |
| Kingwall Contracts (Partitions) Limited | Wholesale & retail | 1964 |
| Kinn Property Development Limited | Real estate | 1987 |
| Kiril Uzunov Ltd | Construction | 2006 |
| Kishone Enterprises Limited | Wholesale & retail | 2012 |
| Kiss Klip Limited | Wholesale & retail | 2025 |
| Kivo Group Ltd | Wholesale & retail | 2026 |
| Kivrem Limited | Hospitality | 2023 |
| Kizai Kitchen Ltd | Hospitality | 2024 |
| Kizai London Ltd | Hospitality | 2024 |
| KJL London Consulting Limited | Professional & scientific | 2018 |
| KKP Health Limited | Professional & scientific | 2025 |
| KL Elite Building Services Ltd | Construction | 2025 |
| KLC 2019 Properties Ltd | Real estate | 2022 |
| Klimos Limited | Real estate | 2024 |
| KLM Kent Transport Ltd | Transport & logistics | 2022 |
| KLS Socials Ltd | Information & communication | 2024 |
| Klukhman Properties Ltd | Real estate | 2023 |
| KM Landscaping & Construction Ltd | Administrative & support | 2014 |
| KMJ London Ltd | Real estate | 2026 |
| Kngcompany Limited | Health & social care | 2017 |
| Knight Munro Ltd | Health & social care | 2025 |