| K & JA Robinson Ltd | Other services | 2018 |
| K Kelani Limited | Real estate | 2020 |
| K R Electrical Contractors (N.E) Limited | Construction | 2021 |
| K Walker Groundworks Limited | Construction | 2016 |
| K&C Lettings Ltd | Real estate | 2020 |
| K&C Render & Damp Proofing Specialists Limited | Construction | 2018 |
| K&P Trading Ltd | Wholesale & retail | 2026 |
| K.F Elec-Tech Services Limited | Professional & scientific | 2007 |
| K.R Site Services Limited | Construction | 2018 |
| K.W Joinery Services Ltd | Construction | 2021 |
| KAA Enginerring Ltd | Professional & scientific | 2024 |
| Kabawest Corporation Limited | Real estate | 2008 |
| Kadense Limited | Information & communication | 2025 |
| Kaffeehaus Limited | Hospitality | 2013 |
| Kaiburr Ltd | Information & communication | 2025 |
| Kaizen Business Development Ltd | Education | 2022 |
| KAL Investco Limited | Financial services | 2018 |
| Kalafrana Management Company Limited | Households | 1989 |
| Kale and Kove Property Limited | Construction | 2025 |
| Kaleido Music UK Ltd | Information & communication | 2015 |
| KAM Connections Limited | Construction | 2020 |
| Kamo Durham Ltd | Other services | 2022 |
| Kanaya Ltd | Health & social care | 2018 |
| Kanda-Gadgets Ltd | Wholesale & retail | 2021 |
| Kanpekix Ltd | Wholesale & retail | 2026 |
| Kanwali Ltd | Wholesale & retail | 2024 |
| KAP & TAN Limited | Real estate | 2025 |
| Kapibala Limited | Wholesale & retail | 2024 |
| Karibu Homes Limited | Real estate | 2022 |
| Karossa Asset Management Ltd | Real estate | 2008 |
| Karu Consulting Ltd. | Professional & scientific | 2014 |
| Kason Construction Limited | Construction | 2003 |
| Katem Holdings Limited | Extraterritorial | 2025 |
| Katem Logistics Limited | Transport & logistics | 2007 |
| Katem Property Limited | Extraterritorial | 2025 |
| Katnic Limited | Wholesale & retail | 2011 |
| KB Group (NE) Ltd | Construction | 2019 |
| KCB Property Developments Limited | Construction | 2025 |
| Kears Services Ltd | Construction | 2023 |
| Kearsley & Sons (Holdings) Limited | Financial services | 2025 |
| Kearsley & Sons Limited | Other services | 2018 |
| Keaton Jennings Limited | Arts & recreation | 2017 |
| KEC Professional Consulting Services Ltd | Information & communication | 2017 |
| Kedebo Ltd | Wholesale & retail | 2025 |
| Keith Fenwick Electricals Ltd. | Manufacturing | 2013 |
| Keith Lines Holdings Limited | Financial services | 2026 |
| Keith Mallard Training Ltd. | Administrative & support | 2015 |
| Kekec Ltd | Wholesale & retail | 2025 |
| Kell Holdings Limited | Financial services | 2018 |
| Kelly & Kelly Group Ltd | Construction | 2017 |
| Kendall Property Services Ltd | Financial services | 2006 |
| Kenmor Psychological Consultancy Limited | Health & social care | 2009 |
| Kennoxhead SPV Limited | Real estate | 2023 |
| Kern Forst Limited | Real estate | 2007 |
| Keryx Communications Limited | Information & communication | 2020 |
| Kesh Teams Ltd | Hospitality | 2024 |
| Ketenpere Holding Ltd | Wholesale & retail | 2023 |
| Kevin Lane Oxford Ltd | Professional & scientific | 2008 |
| Kevin Moran Construction Limited | Construction | 2017 |
| Key Access Ltd | Other services | 2011 |
| Keystonation Ltd | Wholesale & retail | 2026 |
| Keystone Luxe Ltd | Real estate | 2025 |
| KG Ducting Limited | Construction | 2017 |
| KGB Groundworks Limited | Construction | 2024 |
| Khan's Fish Bar & Pizzeria Ltd | Hospitality | 2019 |
| Khokar & Co Properties Ltd | Real estate | 2025 |
| KHT Home Improvement Ltd | Construction | 2026 |
| Kielder Water & Forest Park Development Trust | Administrative & support | 2010 |
| Kilford Furniture Makers Limited | Manufacturing | 2026 |
| Killoch Energy SPV Limited | Real estate | 2023 |
| Kimbetty Limited | Real estate | 2017 |
| Kimmik Ltd | Public administration | 2025 |
| Kimz Ltd | Manufacturing | 2025 |
| Kinda Milky Ltd | Professional & scientific | 2026 |
| Kinder Klub Ltd | Wholesale & retail | 2024 |
| Kinderton Developments Limited | Professional & scientific | 2003 |
| Kinghorn Electric Vehicles Ltd | Wholesale & retail | 2024 |
| Kingsgate Dental Practice Limited | Health & social care | 2014 |
| Kingswood Properties (North East) Limited | Real estate | 2001 |
| Kiss Oriental Bakery Ltd | Hospitality | 2013 |
| Kitchenhub Limited | Wholesale & retail | 2008 |
| Kitts Pool Ch-Le-St Ltd | Hospitality | 2026 |
| Kitts Pool Room Limited | Hospitality | 2021 |
| Kjam Groundworks Ltd | Construction | 2015 |
| KJC Properties Ltd | Real estate | 2025 |
| KJT Stores Ltd | Wholesale & retail | 2025 |
| KJW Inspection Ltd | Professional & scientific | 2013 |
| KK Entertainment Ltd | Professional & scientific | 2023 |
| KL Systems Ltd | Information & communication | 2019 |
| KLA Leisure Ltd | Hospitality | 2016 |
| Klinchr Ltd | Information & communication | 2026 |
| KLS PUB Group Ltd | Hospitality | 2024 |
| Klute Limited | Professional & scientific | 2010 |
| KMB Groundworks & Paving Services Ltd | Construction | 2018 |
| Kmmart Ltd | Health & social care | 2018 |
| Knockalougha Investments Limited | Real estate | 2025 |
| Knot Theory Fashion House Limited | Wholesale & retail | 2025 |
| Know Your Town Limited | Professional & scientific | 2020 |
| Knowlify Ltd | Professional & scientific | 2025 |
| KO Bathrooms Ltd | Construction | 2015 |