| Karan Construction Services Ltd | Construction | 2026 |
| Karan Lettings Ltd | Real estate | 2025 |
| Karanshah Transport Limited | Transport & logistics | 2025 |
| Kararaff Developments Limited | Real estate | 2018 |
| Karen E Newman Limited | Professional & scientific | 2022 |
| Karina YCE TRS Limited | Transport & logistics | 2022 |
| Karisit Digital Limited | Information & communication | 2025 |
| Kariyapz Ltd | Wholesale & retail | 2025 |
| Karl Demner Design Ltd | Professional & scientific | 2025 |
| Karmara Limited | Wholesale & retail | 2020 |
| Karma’S Properties Ltd | Households | 2025 |
| Karol Heating and Plumbing Limited | Construction | 2020 |
| Karolajnshop Ltd | Wholesale & retail | 2021 |
| Karols Care Ltd | Public administration | 2019 |
| Karuzza Limited | Other services | 2024 |
| Karvyn Limited | Wholesale & retail | 2025 |
| Karwanluton Limited | Hospitality | 2022 |
| KAS Contractors Ltd | Construction | 2023 |
| Kasavu Rail Limited | Construction | 2016 |
| Kash Globally Ltd | Construction | 2025 |
| Kashi Traders Limited | Transport & logistics | 2019 |
| Kashmir Stores Luton Ltd | Wholesale & retail | 2017 |
| Kashmir Carpet and Furniture Ltd | Wholesale & retail | 2023 |
| Kashmir Catering Ltd | Hospitality | 2021 |
| Kashmir Catering Services Ltd | Hospitality | 2019 |
| Kashmir Halal Meat Luton Ltd | Wholesale & retail | 2018 |
| Kashmir Press Club UK Ltd | Manufacturing | 2025 |
| Kashmiri Zaiqa Limited | Hospitality | 2024 |
| Katena Ltd | Transport & logistics | 2014 |
| Kathleen Court (Luton) Management Company Limited | Households | 2007 |
| Kathleen Kitsell - Trained Animals for Film & TV Ltd | Arts & recreation | 2025 |
| Kathryn Cooper Consultancy Limited | Professional & scientific | 2026 |
| Katjun Limited | Financial services | 2023 |
| KATX9 Ltd | Wholesale & retail | 2018 |
| KAU (Luton) Holdings Limited | Financial services | 2019 |
| Kaur Online Business Limited | Wholesale & retail | 2024 |
| Kauser Ahmed Properties Limited | Real estate | 2022 |
| Kavanya & Kavinan Ltd | Wholesale & retail | 2025 |
| Kavee Innovation Ltd | Other services | 2024 |
| Kavra Enterprises Ltd | Construction | 2026 |
| Kawa Limited | Health & social care | 2011 |
| Kawoo-Luton Limited | Hospitality | 2025 |
| KAY Auto Solutions Limited | Wholesale & retail | 2026 |
| Kaya House Luton Ltd | Hospitality | 2025 |
| Kaya Lounge Bedford Ltd | Hospitality | 2024 |
| Kaya Water and Fire Ltd | Construction | 2025 |
| Kayali Properties Ltd | Real estate | 2024 |
| Kayan Market Ltd | Wholesale & retail | 2026 |
| KAZ Electrics Ltd | Construction | 2026 |
| KAZ Neuro Health Limited | Health & social care | 2026 |
| KAZ Security Ltd | Administrative & support | 2022 |
| KAZ Tools Ltd | Wholesale & retail | 2025 |
| Kazi Construction Ltd | Construction | 2025 |
| Kazi Holdings Ltd | Financial services | 2018 |
| Kazmi & Co Optics Ltd | Other services | 2023 |
| Kazmi Estates Ltd | Real estate | 2022 |
| Kazmi Tutors Limited | Education | 2025 |
| KB Build Ltd | Construction | 2025 |
| KB Ghost Service Ltd | Construction | 2022 |
| Kbader Ltd | Health & social care | 2022 |
| Kbeebeauty Studios Ltd | Professional & scientific | 2024 |
| KBG Enterprise Ltd | Real estate | 2021 |
| KBK Windows Ltd | Construction | 2018 |
| KBM Secretarial Services Ltd | Administrative & support | 2024 |
| Kbmk Ltd | Construction | 2026 |
| KBZ Elite Wear Limited | Wholesale & retail | 2025 |
| KC Crawford Limited | Transport & logistics | 2016 |
| KC UK Construction Ltd | Construction | 2016 |
| KCA Construction Ltd | Construction | 2017 |
| KCA Hospitality Limited | Hospitality | 2020 |
| KCB Events Limited | Administrative & support | 2018 |
| KCK UK Properties Limited | Real estate | 2024 |
| Kcluk Ltd | Information & communication | 2024 |
| KCS Building Limited | Construction | 2017 |
| KCY 168 Ltd | Hospitality | 2022 |
| KD & Garcha Limited | Administrative & support | 2019 |
| KD Fit Trading AS Fitter Body Ladies Watford Ltd | Arts & recreation | 2025 |
| KD. Permanent Makeup Artist Ltd | Other services | 2023 |
| KDA1 Limited | Wholesale & retail | 2025 |
| KDL Health&Beauty Ltd | Other services | 2024 |
| KEA International Limited | Professional & scientific | 2019 |
| Keava Construction Ltd | Construction | 2020 |
| Keech Hospice | Health & social care | 1994 |
| Keech Hospice (Trading) Ltd | Wholesale & retail | 2009 |
| Keemnet Ltd | Information & communication | 2013 |
| Keena Globe Limited | Administrative & support | 2025 |
| Keep IT Bamboo Ltd | Wholesale & retail | 2024 |
| Keep IT Moving Transport Ltd | Transport & logistics | 2025 |
| Keepers Barns Management Company Limited | Households | 2017 |
| Keephearing Limited | Administrative & support | 2009 |
| Keeping a Head Ltd | Information & communication | 2021 |
| Kejsi Contractors Ltd | Administrative & support | 2016 |
| Kelco Developments Ltd | Construction | 2021 |
| Kelevra London Ltd | Administrative & support | 2024 |
| Kelkit Kebab Limited | Hospitality | 2025 |
| Kell Homes Ltd | Construction | 2025 |
| Kelly Construction (Luton) Limited | Construction | 2021 |
| Kelly Fire Protection Ltd | Public administration | 2026 |
| Kelly Gray Hairdressing Limited | Other services | 2018 |
| Kelly Plastering Services Ltd | Construction | 2015 |