| JSP Construction Services Ltd | Construction | 2026 |
| Jstars Engineering Ltd | Manufacturing | 2024 |
| JSV Foods Ltd | Wholesale & retail | 2025 |
| JT Engineering Ltd | Construction | 2025 |
| Ju-De-Mich Ltd | Hospitality | 2015 |
| Julian Millan Electrical Ltd | Construction | 2015 |
| Jump Into Sports Ltd | Education | 2025 |
| Jumsol Ltd | Real estate | 2011 |
| Junior Elite Football Club Limited | Arts & recreation | 2021 |
| Juniper Stories Limited | Professional & scientific | 2025 |
| Jupiter Acting Limited | Information & communication | 2012 |
| Just Better Limited | Wholesale & retail | 2020 |
| Just Billit Limited | Manufacturing | 2017 |
| Just in Time Housing Ltd | Real estate | 2025 |
| Just Piotr Ltd | Wholesale & retail | 2025 |
| Justeve London Beauty Ltd | Wholesale & retail | 2023 |
| Justgrad Ltd | Administrative & support | 2023 |
| Justinas Mockevicius Limited | Information & communication | 2026 |
| Jvac Services Ltd | Construction | 2025 |
| JW Auto Body Repairs Ltd | Wholesale & retail | 2024 |
| JWR Digital Ltd | Information & communication | 2025 |
| JYA Investments Ltd | Real estate | 2025 |
| K & F Clean Ltd | Administrative & support | 2025 |
| K Autos Croydon Ltd | Wholesale & retail | 2023 |
| K H L Constructions Limited | Construction | 2008 |
| K Kebab House Limited | Hospitality | 2023 |
| K Nyame Limited | Wholesale & retail | 2017 |
| K Parekh Ltd | Other services | 2020 |
| K&Ash Limited | Financial services | 2024 |
| K&Ash Property BR Ltd | Real estate | 2024 |
| K&Ash Property HS Ltd | Real estate | 2024 |
| K&S Halal Meat Limited | Wholesale & retail | 2022 |
| K.A Auto Solutions Ltd | Wholesale & retail | 2020 |
| K.A.S.H Retailing Limited | Wholesale & retail | 2013 |
| K.R Shipping Ltd | Wholesale & retail | 2025 |
| K4CARS Limited | Wholesale & retail | 2016 |
| Kabul Repair Centre Ltd | Administrative & support | 2017 |
| KAG Business Ltd | Wholesale & retail | 2026 |
| Kaglobal Ltd | Wholesale & retail | 2024 |
| Kainaat Travel Services Ltd | Transport & logistics | 2015 |
| Kajura Properties Ltd | Real estate | 2024 |
| Kalconstruction Limited | Construction | 2023 |
| Kamacho Services Ltd | Construction | 2018 |
| Kamsy Food Stuffs &Delicacies Ltd | Hospitality | 2026 |
| Kandulescents Ltd | Manufacturing | 2023 |
| Kangore PVT Limited | Wholesale & retail | 2014 |
| Karamoja Community UK Foundation | Other services | 2018 |
| Karen Wright Ltd | Other services | 2016 |
| Kari Kars Limited | Wholesale & retail | 2025 |
| Karostaunch Enterprise UK Limited | Real estate | 2020 |
| Kash Assets Ltd | Real estate | 2020 |
| Kash Property Solutions Ltd | Construction | 2020 |
| Kasmo Auto Sell Ltd | Wholesale & retail | 2025 |
| Kaydee Associates Ltd | Professional & scientific | 2007 |
| Kazanir Business Consultancy Ltd | Professional & scientific | 2020 |
| Kazy Store Ltd | Wholesale & retail | 2026 |
| KBR Investments (KA) Limited | Real estate | 2025 |
| KC Suppliers Limited | Wholesale & retail | 2023 |
| KCE Services Limited | Health & social care | 2022 |
| KCT London Limited | Construction | 2011 |
| Keem Logistics Ltd | Transport & logistics | 2018 |
| Keeman Limited | Construction | 2014 |
| Keenjhar Limited | Wholesale & retail | 2023 |
| Keep IT All-Clean Ltd | Administrative & support | 2025 |
| Keir Holding Ltd | Real estate | 2023 |
| KEL Cosec Associates Limited | Extraterritorial | 2019 |
| Kempton Housing Services Limited | Hospitality | 2021 |
| Kemzion Hub Ltd | Wholesale & retail | 2025 |
| Kencots Cakes Ltd | Manufacturing | 2026 |
| Kerala Cultural and Welfare Association | Other services | 2009 |
| Keti &Co Limited | Other services | 2019 |
| Keystone Home Support Services Ltd | Transport & logistics | 2023 |
| KG Property Assets Limited | Real estate | 2025 |
| Khadijah Patel Limited | Health & social care | 2015 |
| Khairukum Academy Ltd | Education | 2023 |
| Khairukum Ltd | Education | 2024 |
| Khan & Sons Properties Ltd | Real estate | 2023 |
| Khan Security Solutions Ltd | Administrative & support | 2016 |
| Khinda Brothers Ltd | Other services | 2023 |
| Khoji Psychological Tools Ltd | Information & communication | 2025 |
| Kiddiesland Childcare Limited | Health & social care | 2023 |
| Killarney 377 Limited | Other services | 2012 |
| KIM Nails Salon Ltd | Other services | 2023 |
| Kinda Construction Ltd | Construction | 2018 |
| Kindora International Ltd | Wholesale & retail | 2025 |
| Kinkel Consults Ltd | Information & communication | 2025 |
| KISSCUTS335 Ltd | Other services | 2021 |
| Kitabawo Ltd | Transport & logistics | 2015 |
| KK Fresh Foods & OFF Licence Limited | Wholesale & retail | 2018 |
| KKB Services Limited | Health & social care | 2018 |
| Klevah Ltd | Education | 2012 |
| Knights Drycleaners Limited | Other services | 2000 |
| Knowland Mews Management Ltd | Households | 2018 |
| KNV Services Ltd | Wholesale & retail | 2021 |
| Kolsawala Ltd | Wholesale & retail | 2026 |
| Kominto Ltd | Wholesale & retail | 2019 |
| Konius Ltd | Professional & scientific | 2024 |
| Konzept UK Holdings Ltd | Financial services | 2023 |
| Kovjack Ltd | Other services | 2015 |
| KP Medical London Limited | Administrative & support | 2011 |