| Kate Stella Limited | Professional & scientific | 2019 |
| Kateways Limited | Households | 2025 |
| Katharine House Hospice Trust | Health & social care | 1987 |
| Katie Loxton Limited | Wholesale & retail | 2014 |
| Katie Tyler Communications Limited | Professional & scientific | 2018 |
| Kayi Fitness Club Ltd | Arts & recreation | 2021 |
| KB Roofing & Building Ltd | Construction | 2024 |
| KC Construction Services Ltd | Construction | 2019 |
| Kcdc Limited | Information & communication | 2018 |
| KCM Electrical (Cotswolds) Limited | Construction | 2020 |
| Kearney's Inside Outside Catering Company Limited | Hospitality | 2004 |
| Kebabish Banbury Limited | Hospitality | 2023 |
| Kedasa Ltd | Construction | 2023 |
| KEDDOX2 Ltd | Transport & logistics | 2024 |
| Keel & Grain Ltd | Manufacturing | 2025 |
| Keel Insight Ltd | Professional & scientific | 2023 |
| Keenskill Limited | Real estate | 2002 |
| Keeping-Track Limited | Information & communication | 2025 |
| Keith Hudspith Ltd | Professional & scientific | 2018 |
| Keith Marsden Computing Ltd | Information & communication | 2006 |
| Keldan Homes Ltd | Construction | 2014 |
| Kelselia Logistics Limited | Transport & logistics | 2021 |
| Kempthorne Consultancy Limited | Professional & scientific | 2016 |
| Kemr Limited | Information & communication | 2016 |
| Kendale Business Services Limited | Professional & scientific | 2010 |
| Kennen Technology Limited | Information & communication | 2023 |
| Kenneth Charles Landscapes Limited | Construction | 2019 |
| Kentfield & Co Limited | Administrative & support | 2023 |
| Kentfield Private Finance Limited | Financial services | 2016 |
| Kenya Properties Ltd | Real estate | 2025 |
| Kenyons Containers Limited | Wholesale & retail | 1945 |
| Kerb Side Motors Limited | Wholesale & retail | 2016 |
| Kerrro Ltd | Information & communication | 2026 |
| Keston Technologies Ltd | Professional & scientific | 2006 |
| Kestrel Collab Media Limited | Professional & scientific | 2024 |
| Keter Group Holding Limited | Financial services | 2024 |
| KEV Curier Ltd | Transport & logistics | 2024 |
| Key Professional Services Limited | Hospitality | 1989 |
| Keydeal Ltd | Wholesale & retail | 2023 |
| Keylogbook Limited | Information & communication | 2012 |
| Keymite Limited | Administrative & support | 1989 |
| Keys Leigh Properties Limited | Real estate | 1997 |
| Keystoneworks Group Ltd | Information & communication | 2026 |
| KFI Limited | Real estate | 2009 |
| Khalid & SON of Banbury Limited | Transport & logistics | 2020 |
| KHS1 Ltd | Wholesale & retail | 2026 |
| KI Creations Limited | Information & communication | 2017 |
| Kichiscakesnmore Limited | Extraterritorial | 2016 |
| Kidlington Assisted Transport CIC | Transport & logistics | 2017 |
| Kielman Mortgages Limited | Financial services | 2017 |
| Kiftsgate Developments Ltd | Real estate | 2011 |
| Kiln Cottages Limited | Manufacturing | 2020 |
| Kimaro Inc. Ltd | Health & social care | 2016 |
| Kimbed Care Services Ltd | Health & social care | 2024 |
| KIN Care Solutions Ltd | Administrative & support | 2026 |
| Kindergarden Plants Ltd. | Extraterritorial | 1992 |
| Kinena Farms Agrotourism Limited | Agriculture & fishing | 2025 |
| King Custom Paint Works Limited | Construction | 2019 |
| Kingfisher Poolcare Limited | Construction | 1992 |
| Kingfisher Power Cleaning Limited | Construction | 2005 |
| Kingslands Property Management LLP | | 2021 |
| Kirby House Enterprises Limited Liability Partnership | | 2004 |
| Kiss Consultancy Limited | Administrative & support | 2009 |
| Kitshop Digital Systems Limited | Professional & scientific | 2003 |
| KJ Cherry Holdings Limited | Financial services | 2021 |
| KJS Accountancy & Business Advisors Ltd | Professional & scientific | 2023 |
| KL Cheltenham Limited | Extraterritorial | 2024 |
| KL Gloucester Limited | Extraterritorial | 2024 |
| KL Ventures Limited | Hospitality | 2001 |
| Klaus Hospitality Ltd | Hospitality | 2025 |
| KLD Solutions Ltd | Agriculture & fishing | 2021 |
| KLN Trans Ltd | Transport & logistics | 2023 |
| KLV Holdco Limited | Extraterritorial | 2024 |
| KM Specialist Electrical Services Ltd | Construction | 2018 |
| KMS Litho Limited | Manufacturing | 2002 |
| Knightsbridge INT Property Ltd | Administrative & support | 2011 |
| Kocsal 2 Ltd | Real estate | 2019 |
| Kocsal Limited | Real estate | 2015 |
| KODIAK1981 Ltd | Transport & logistics | 2025 |
| Koka Synergy Ltd | Professional & scientific | 2025 |
| Kola Design Ltd | Manufacturing | 2024 |
| Kolluma Ltd | Financial services | 2023 |
| Konig Colours Limited | Wholesale & retail | 2013 |
| Konig Design Limited | Administrative & support | 2006 |
| Koolen Consulting Limited | Professional & scientific | 2022 |
| Koskbanbury Ltd | Hospitality | 2025 |
| KPB Agyemang Ltd | Transport & logistics | 2023 |
| Krayt Limited | Arts & recreation | 2012 |
| Krazy Savers Limited | Wholesale & retail | 2023 |
| Kreative Group UK Limited | Wholesale & retail | 2025 |
| KRI Delivery Ltd | Transport & logistics | 2026 |
| Kris Garage Ltd | Wholesale & retail | 2018 |
| Kris PUP Services Limited | Administrative & support | 2023 |
| Kropka European Food Store Limited | Wholesale & retail | 2019 |
| KS Business Solutions Ltd | Administrative & support | 2006 |
| KS Construction Ltd | Construction | 2009 |
| KSB Consultants Ltd | Professional & scientific | 2023 |
| KSC Property Group Limited | Real estate | 2022 |
| Ksylo Limited | Manufacturing | 2025 |
| Kuchenhaus Aylesbury Limited | Wholesale & retail | 2022 |