| Karmac-Carlton Limited | Professional & scientific | 2025 |
| Karnheath Limited | Construction | 1978 |
| Karol Marketing (London) Limited | Professional & scientific | 2013 |
| Karol Marketing Limited | Professional & scientific | 1999 |
| Karrico UK Ltd | Construction | 2019 |
| Karrthikeya Health Care Limited | Administrative & support | 2023 |
| KAS Health Ltd | Health & social care | 2021 |
| KAS Locums Limited | Health & social care | 2015 |
| Kasamusik Group Ltd | Information & communication | 2025 |
| Kasaservices Group Ltd | Administrative & support | 2022 |
| Kashmir Tandoori (Shiremoor) Ltd | Hospitality | 2020 |
| Kashmir Tandoori South Shields Ltd | Hospitality | 2025 |
| Kashyap Medicals Ltd | Professional & scientific | 2017 |
| Katherines Florists Limited | Wholesale & retail | 1946 |
| Katherines Ltd | Wholesale & retail | 2024 |
| Kathleen Heron's Childminding Services Ltd | Health & social care | 2023 |
| Kathyathyem Property Ltd | Real estate | 2024 |
| Katie the Accountant Limited | Professional & scientific | 2018 |
| Katon Ltd | Construction | 2020 |
| Katory Services Ltd | Health & social care | 2019 |
| Katuu. Limited | Health & social care | 2025 |
| Kausar Trading Ltd | Wholesale & retail | 2026 |
| Kavali PH Limited | Transport & logistics | 2024 |
| Kaydian Design Limited | Wholesale & retail | 2004 |
| KAZ Associates Ltd | Health & social care | 2025 |
| Kazamuki Industries Ltd | Wholesale & retail | 2019 |
| KB Bagels Ltd | Hospitality | 2024 |
| KB Pointing&Brickwork Ltd | Construction | 2025 |
| Kba-Cardiology Ltd | Health & social care | 2014 |
| KBM and Foxfields Residents Management Company Limited | Real estate | 2025 |
| KBP Property Ltd | Real estate | 2026 |
| KC Decking Ltd | Construction | 2010 |
| KC Equity Ltd | Financial services | 2025 |
| KC Fire Protection Ltd | Transport & logistics | 2026 |
| KC Heating and Plumbing Ltd | Construction | 2020 |
| KC Lighting Ltd | Arts & recreation | 2025 |
| KC Wharton Property Ltd | Real estate | 2022 |
| KCD Solutions Ltd | Construction | 2018 |
| Kcim Healthcare Ltd | Extraterritorial | 2023 |
| KCM Realisations Limited | Manufacturing | 1972 |
| KCR Solutions Limited | Administrative & support | 2004 |
| Kcxconsult Limited | Information & communication | 2025 |
| KD Care Services Ltd | Health & social care | 2020 |
| KD Logistics Ltd | Wholesale & retail | 2024 |
| Kdel Supports Ltd | Health & social care | 2025 |
| KDT Property Services Ltd | Construction | 2015 |
| KE Promotions Ltd | Arts & recreation | 2011 |
| Kebab FIX Ltd | Hospitality | 2025 |
| Keda Consulting Limited | Professional & scientific | 2013 |
| Keelman Group Ltd | Real estate | 2025 |
| Keep Cover Limited | Financial services | 2023 |
| Keep IT Short Ltd | Transport & logistics | 2025 |
| Keep ME Clean Services Ltd | Administrative & support | 2025 |
| Keeper of Kittens Ltd | Hospitality | 2020 |
| Keepin IT Ltd | Professional & scientific | 2018 |
| Keeping Inn Developments Limited | Financial services | 2022 |
| Keeping Inn Limited | Hospitality | 1997 |
| Keepl Social Limited | Information & communication | 2021 |
| Keeplsv Limited | Information & communication | 2025 |
| Keepright Accounting Limited | Professional & scientific | 2014 |
| Keetonslandscapingandfencing Ltd | Administrative & support | 2025 |
| Keighley Metering Services Limited | Extraterritorial | 2016 |
| Keiron Morris Logistics Ltd | Transport & logistics | 2025 |
| Keith Brownsword Project Management Ltd | Professional & scientific | 2026 |
| Keith Nichol Roofing Ltd | Construction | 2016 |
| Keith Piddock Limited | Financial services | 2007 |
| Keith Telecoms Ltd | Construction | 2024 |
| Keith Waters Enterprises Ltd | Professional & scientific | 2023 |
| Keith's Coaches Limited | Transport & logistics | 1998 |
| Keke Waste Disposal Ltd | Transport & logistics | 2023 |
| Kelburn House Limited | Real estate | 2017 |
| Kell's Closet Limited | Other services | 2025 |
| Keller Process Limited | Professional & scientific | 2015 |
| Kells Angels Limited | Arts & recreation | 2013 |
| Kelly Consultancy Services Ltd | Professional & scientific | 2021 |
| Kelly Hendry School of Irish Dancing Limited | Education | 2013 |
| Kelvis Limited | Transport & logistics | 2026 |
| Kema Contractors Ltd | Wholesale & retail | 2019 |
| Kema KAY Holdings Limited | Financial services | 2022 |
| Kema KAY Limited | Information & communication | 2021 |
| Kema KAY Properties Limited | Real estate | 2024 |
| Kemkleen International Limited | Wholesale & retail | 1968 |
| KEN Smith Roofing Limited | Construction | 2017 |
| Kendal Automotive Ltd | Wholesale & retail | 2025 |
| Kendal House Properties (RP) Limited | Health & social care | 2026 |
| Kendal House Properties Limited | Real estate | 2012 |
| Kendor Consultants Limited | Professional & scientific | 2019 |
| Kendy Ltd | Hospitality | 2026 |
| Kenif Emerald Limited | Health & social care | 2022 |
| Kenilworth Creations Ltd | Wholesale & retail | 2021 |
| Kenmor Ceilings & Partitions Limited | Construction | 1995 |
| Kennedy & Rhind Ltd | Hospitality | 2020 |
| Kennedy Scaffolding Company Limited | | 1982 |
| Kennedy's of Gosforth Ltd | Water & waste | 2019 |
| Kennedy's Removals and Storage Ltd | Transport & logistics | 2023 |
| Kennedys Tuning Ltd | Other services | 2024 |
| Kenny Financial Planning Limited | Financial services | 2023 |
| Kensington House RTM Company Limited | Real estate | 2014 |
| Kensington West Productions Limited | Information & communication | 1984 |
| Kenton Bathroom Centre Ltd | Construction | 2019 |