| K.W. Resorts Ltd | Real estate | 2005 |
| K3 Tyres Limited | Wholesale & retail | 2025 |
| K4P Burgess LLP | | 2002 |
| Kaana | Education | 2009 |
| Kabab-Shish Ltd | Hospitality | 2026 |
| Kabeer Tourism Limited | Administrative & support | 2025 |
| Kacy Global Ventures Limited | Health & social care | 2019 |
| Kaddy Box Holdings Ltd | Administrative & support | 2021 |
| Kagmad Ltd | Wholesale & retail | 2022 |
| Kaia Barbers Limited | Other services | 2019 |
| Kaiser Transport Limited | Administrative & support | 2015 |
| Kaiv Goods Ltd | Wholesale & retail | 2025 |
| Kaiv Residence Ltd | Real estate | 2026 |
| Kaiv Solutions Ltd | Information & communication | 2025 |
| Kajrin Investment LLP | | 2023 |
| Kaka Baban Ltd | Other services | 2013 |
| Kalara IT Services Ltd | Information & communication | 2020 |
| Kaleem & BRO Co Ltd | Wholesale & retail | 2024 |
| Kaleidoscope Children's Centre of Education and Arts LLP | | 2022 |
| Kalypton Financial Holdings Limited | Financial services | 2020 |
| Kalypton Holdings Limited | Financial services | 2022 |
| Kalypton Technology Holdings Limited | Financial services | 2019 |
| Kalzah Ltd | Information & communication | 2024 |
| KAM & Co Properties Ltd | Real estate | 2025 |
| KAM Digitizers Limited | Information & communication | 2013 |
| Kandies Properties Limited | Real estate | 2021 |
| Kandies Sweets Limited | Wholesale & retail | 2002 |
| Kang Engineering Limited | Professional & scientific | 2011 |
| Kanmara Accountancy Limited | Professional & scientific | 2022 |
| Kansara Group Limited | Professional & scientific | 2019 |
| Kantilal and Sons London Ltd | Construction | 2022 |
| Kappanu Ltd | Transport & logistics | 2018 |
| Karibu Africani Ltd | Hospitality | 2024 |
| Karl Singporewala + the Design Bureau Ltd | Professional & scientific | 2026 |
| Karmakula Ltd | Wholesale & retail | 2019 |
| Kashaf Mirza Ltd | Information & communication | 2012 |
| Kashmir Zaiqa Ltd | Hospitality | 2020 |
| Kasowi Ltd | Hospitality | 2024 |
| Kastrati Building Maintenance Ltd | Construction | 2022 |
| KAT Loosemore Ltd | Professional & scientific | 2025 |
| Kattanyonta Limited | Health & social care | 2024 |
| Kaur Singh Kaur Limited | Real estate | 2023 |
| Kaushamiconsultancy Ltd | Information & communication | 2024 |
| Kavaniconstruction Tools & Hardware Retail Ltd | Wholesale & retail | 2026 |
| KB Carpentry and Construction Limited | Construction | 2021 |
| KB Refurbishment Ltd | Construction | 2020 |
| KB Services (Gatwick) Limited | Construction | 2021 |
| Kbs(Moveable Walls) Ltd | Construction | 2007 |
| KC Home Solutions Ltd | Construction | 2023 |
| KC Roofing & Construction Ltd | Construction | 2022 |
| KCL Cloud Limited | Information & communication | 1993 |
| KCL E-Document Solutions Limited | Information & communication | 2001 |
| Kctf Property Holdings Ltd | Real estate | 2023 |
| KD Plumbing Solutions Ltd | Construction | 2025 |
| KDW Online UK Limited | Wholesale & retail | 2022 |
| Kebab and Fish Broadfield Ltd | Hospitality | 2018 |
| Keegans Pool Company Limited | Construction | 2011 |
| Keen Digital Ltd | Professional & scientific | 2017 |
| Keepr Group Ltd | Manufacturing | 2025 |
| Keldhead Brick Company Limited | Agriculture & fishing | 1972 |
| Kelgray Products Ltd. | Wholesale & retail | 1983 |
| Kelley Peers Design Partnership Limited | Professional & scientific | 2015 |
| Kelloyd Ltd | Hospitality | 2023 |
| Kellyread Construction Ltd | Construction | 2026 |
| Kellys Property Maintenance Ltd | Construction | 2025 |
| Kelvin Precision Products Ltd | Professional & scientific | 2012 |
| Kemtek Ltd | Information & communication | 2019 |
| Kemucol Services Limited | Health & social care | 2015 |
| Kender Properties Limited | Construction | 1989 |
| Kenneth Ward & Company (Resorts) Limited | Real estate | 1982 |
| Kennington Dental Care Ltd | Health & social care | 2011 |
| Kent Cheer Academy | Arts & recreation | 2022 |
| Kent Tropical Interiors Limited | Administrative & support | 2006 |
| Kentapol Limited | Health & social care | 2009 |
| Keshav Enterprises Limited | Wholesale & retail | 2025 |
| Kestrel Investments Limited | Other services | 1996 |
| Ketcom Ltd | Hospitality | 2025 |
| Kevin David Ltd | Construction | 2020 |
| Kevin Sole Modelling Limited | Information & communication | 1998 |
| Kewala Limited | Wholesale & retail | 2019 |
| Key Performance Cagers Basketball CIC | Arts & recreation | 2024 |
| Keysight Technologies (Spirent Services) Limited | Information & communication | 1949 |
| KFM Solutions Limited | Construction | 2021 |
| KG Mcgahan Consulting Limited | Professional & scientific | 2011 |
| Khaldoon Bekou Limited | Health & social care | 2025 |
| Khaleefah Society Limited | Other services | 2004 |
| Khalsa Panth UK C.I.C. | Other services | 2024 |
| Khan's Whippy Ltd | Hospitality | 2025 |
| Khans Hire Ltd | Transport & logistics | 2025 |
| Khanz Properties Ltd | Real estate | 2025 |
| Khehra Software Consultants Limited | Information & communication | 1994 |
| Khimera Works Ltd | Information & communication | 2026 |
| Khizar Hayat Limited | Wholesale & retail | 2025 |
| Kids for Kids | Health & social care | 2002 |
| Kilbride Homes Limited | Construction | 2004 |
| Kilnstone Property Ltd | Construction | 2018 |
| Kimbri Limited | Financial services | 2019 |
| KIN Riley Group Ltd | Information & communication | 2016 |
| Kinda Kawaii Ltd. | Wholesale & retail | 2019 |
| Kinetic OS Networks Ltd | Information & communication | 2026 |