| Juventes Homes Limited | Health & social care | 2024 |
| JVG Transport Ltd | Transport & logistics | 2018 |
| JW Science Writing & Consulting Ltd | Professional & scientific | 2021 |
| JWO Agri Services Ltd | Agriculture & fishing | 2023 |
| Jwtk Just Want to Know Limited | Professional & scientific | 2011 |
| JYC Education Ltd | Education | 2018 |
| K & J Invest Ltd | Real estate | 2019 |
| K & Y Engineering Limited | Information & communication | 2002 |
| K Aesthetics Oxford Ltd | Other services | 2022 |
| K Best Choice Limited | Hospitality | 2024 |
| K D B International Limited | Professional & scientific | 1998 |
| K E Davies Limited | Professional & scientific | 2014 |
| K Fleming Consultancy Limited | Health & social care | 2010 |
| K H Estates Limited | Real estate | 2015 |
| K H Nest Ltd | Real estate | 2018 |
| K J Wiskin Brickwork Ltd | Construction | 2005 |
| K&A Drive Solutions Ltd | Transport & logistics | 2023 |
| K&Co Oxford Ltd | Hospitality | 2025 |
| K&D Taxi Limited | Transport & logistics | 2025 |
| K&I Treatz Ltd | Manufacturing | 2026 |
| K&M Techniks Partnership LLP | | 2020 |
| K-Kook Limited | Hospitality | 2026 |
| K. & O. Peros (Oxford) Limited | Real estate | 1986 |
| K.C. Global Group Limited | Wholesale & retail | 2018 |
| K.E.H. Consulting Limited | Wholesale & retail | 2019 |
| K.J.D. Construction Oxford Limited | Construction | 2014 |
| K.J.D. Investments (Oxford) Limited | Real estate | 2019 |
| K.J.D. Maintenance Limited | Administrative & support | 2024 |
| K.S. Garages Limited | Wholesale & retail | 1984 |
| KA Property Limited | Real estate | 2016 |
| Kaaya Mebs Limited | Health & social care | 2018 |
| Kabulicious Afghani Restaurant Ltd | Hospitality | 2024 |
| Kaci Construction Ltd | Construction | 2023 |
| Kadl Enterprise Limited | Wholesale & retail | 2018 |
| KAE Accountancy & Payroll Services Ltd | Professional & scientific | 2022 |
| Kahuro Ltd | Health & social care | 2016 |
| Kaizen Building Group Ltd | Construction | 2024 |
| Kaka Logistics Ltd | Transport & logistics | 2024 |
| KAL Limited | Hospitality | 2003 |
| Kalabria Limited | Hospitality | 2025 |
| Kalamz Limited | Administrative & support | 2026 |
| Kalanoush Ltd | Education | 2024 |
| Kalsam Property Private Limited | Real estate | 2025 |
| Kalyne Limited | Health & social care | 2025 |
| Kamal Sahni Ltd | Health & social care | 2013 |
| Kamatsu/Kamasan Limited | Wholesale & retail | 1983 |
| Kaminah Cleaning Ltd | Administrative & support | 2025 |
| Kamko Motors Ltd | Wholesale & retail | 2023 |
| Kamm Limited | Professional & scientific | 2006 |
| Kamm Property Limited | Real estate | 2018 |
| Kanadia Ltd | Information & communication | 2015 |
| Kaniz Properties Limited | Real estate | 2023 |
| Kantaka Ltd | Information & communication | 2018 |
| Kantiva Travel & Tourism Ltd | Administrative & support | 2025 |
| Karbn Ltd | Information & communication | 2024 |
| Karen Anders Consulting Ltd | Professional & scientific | 2020 |
| Karen Spiller Limited | Professional & scientific | 2011 |
| Kargenera Limited | Professional & scientific | 2020 |
| Karim Khan Limited | Information & communication | 2022 |
| Karla Medical Limited | Health & social care | 2024 |
| Karyatid Limited | Professional & scientific | 2013 |
| KAS Trading & Contracting Limited | Wholesale & retail | 2023 |
| Kasan (UK) Limited | Hospitality | 2012 |
| Kaspar Systems Ltd | Information & communication | 2019 |
| Kastien Coffee Ltd | Professional & scientific | 2015 |
| Kate FOX Limited | Professional & scientific | 2007 |
| Kate Kewley Ltd | Professional & scientific | 2021 |
| Kate Twine Consulting Limited | Professional & scientific | 2009 |
| Kate Walker Fitness Ltd | Health & social care | 2026 |
| Katie Gordon Limited | Real estate | 2020 |
| Katie Millett Ltd | Health & social care | 2023 |
| Katie Read Media Limited | Information & communication | 2016 |
| Katiendu Ltd | Health & social care | 2019 |
| Kaura's Local Limited | Wholesale & retail | 2023 |
| Kaydee Web Limited | Professional & scientific | 2016 |
| Kayiga Industries Ltd | Wholesale & retail | 2019 |
| Kayk Ltd | Hospitality | 2025 |
| Kaylin Groundworks Ltd | Construction | 2025 |
| Kaynest Capital Limited | Financial services | 2025 |
| Kayo Sports Ltd | Wholesale & retail | 2018 |
| Kazan 148 Limited | Hospitality | 2025 |
| Kazan OX3 Limited | Hospitality | 2023 |
| Kazanci International Ltd | Financial services | 2025 |
| Kazkidz Limited | Health & social care | 2009 |
| KB Automotors Ltd | Wholesale & retail | 2026 |
| Kb-Dynamics Ltd | Information & communication | 2023 |
| KB2 Dining Ltd | Hospitality | 2026 |
| Kbap Ltd | Hospitality | 2024 |
| KBR (UK) Limited | Health & social care | 2012 |
| KBS Oxford Ltd | Construction | 2019 |
| Kcrrconsultants Ltd | Information & communication | 2022 |
| KE Pharma Consultants Limited | Information & communication | 2015 |
| Keac Properties Limited | Financial services | 2017 |
| Kebab KID Enterprises Limited | Hospitality | 2022 |
| Kebab KID Limited | Hospitality | 1996 |
| Kebab Marlborough Ltd | Hospitality | 2026 |
| Keble Court (Sunderland Avenue) Management Company Limited | Households | 2012 |
| Keble Properties Limited | Administrative & support | 2010 |
| Keebleandbrooks Ltd | Other services | 2025 |
| Keele Services Limited | Professional & scientific | 2006 |