| Keely Construction Limited | Construction | 2003 |
| Keep ME Fabulous Limited | Wholesale & retail | 2024 |
| Keep Warm Heating Ltd | Administrative & support | 2017 |
| Keeping Clean and Shining Ltd | Administrative & support | 2016 |
| Keere Khar Limited | Real estate | 2019 |
| Keggs'N'Bloggs Limited | Wholesale & retail | 2022 |
| Keith Budge Independent Ltd | Education | 2023 |
| Kekcc Limited | Administrative & support | 2019 |
| Kelinda Consultancy Limited | Professional & scientific | 2021 |
| Kelly & Carl Ltd | Other services | 2021 |
| Kelpie Coffee Limited | Manufacturing | 2023 |
| Kendon Management Limited | Professional & scientific | 2010 |
| Kenilworth Mews Limited | Real estate | 2004 |
| Kenjade Limited | Health & social care | 2016 |
| Kennedy College Oxford Ltd | Education | 2016 |
| Kennedy Psychology Ltd | Health & social care | 2018 |
| Kenneth Payne & Associates Ltd | Public administration | 2023 |
| Kennick Limited | Professional & scientific | 2021 |
| Kennington Barbers Ltd | Other services | 2020 |
| Kennington Brickwork Limited | Construction | 2015 |
| Kennington Fencing & Landscaping Limited | Administrative & support | 2016 |
| Kennington OFF Licence Ltd | Wholesale & retail | 2020 |
| Kennington Plastering Limited | Construction | 2008 |
| Kennon Limited | Wholesale & retail | 2010 |
| Kenny Ryder Ltd | Wholesale & retail | 2024 |
| Kensaj Consulting Services Ltd | Professional & scientific | 2019 |
| Kensan Ltd | Education | 2019 |
| Kensington Properties Group Limited | Construction | 2014 |
| Kenton Burch Ltd | Information & communication | 2015 |
| Kenville Road Management Company Limited | Real estate | 1994 |
| Kenzi Services Ltd | Information & communication | 2024 |
| Kerasi Travel Ltd | Administrative & support | 2021 |
| Kernow Geoscience Limited | Mining & quarrying | 2018 |
| Kerradon Limited | Professional & scientific | 2017 |
| Kerv Limited | Health & social care | 2019 |
| Kerv Property Limited | Real estate | 2020 |
| Keth & Kens Limited | Wholesale & retail | 2025 |
| Ketonex Limited | Professional & scientific | 2009 |
| KEU Ltd | Hospitality | 2018 |
| Kevin Sharpe, Inc. | | 1999 |
| KEW Bridge Apartments Limited | Real estate | 2024 |
| Key Fasteners Limited | Administrative & support | 2004 |
| Key Haven Publications Ltd | Information & communication | 1984 |
| Keylink Property Solutions Ltd | Administrative & support | 2024 |
| KG Oxford Prime Lettings Ltd | Real estate | 2026 |
| Kgds Advisory Ltd | Professional & scientific | 2023 |
| Khalifa Super Store Ltd | Wholesale & retail | 2023 |
| Khalifa Supermarket Ltd | Wholesale & retail | 2025 |
| Khamderm Limited | Hospitality | 2026 |
| Khan's Cash & Carry Ltd | Wholesale & retail | 2026 |
| Khiara Trading Company Limited | Wholesale & retail | 2004 |
| KHM Redwood Limited | Professional & scientific | 2017 |
| Khodadadi Ltd | Administrative & support | 2011 |
| Khurana Traders Ltd | Wholesale & retail | 2018 |
| Khurana Wines Ltd | Water & waste | 2014 |
| Khushi Properties Ltd | Real estate | 2003 |
| Khyber Afghan Cuisine Ltd | Other services | 2011 |
| Kickstand (Lotus Cafe) Limited | Hospitality | 2025 |
| Kickstand Coffee Group Limited | Financial services | 2025 |
| Kickstand Coffee Limited | Hospitality | 2025 |
| Kidlington Property Management Limited | Real estate | 1997 |
| Kids Climbing Shop Ltd | Wholesale & retail | 2021 |
| Kidston Court Management Company Limited | Households | 2011 |
| Kiertam Properties Ltd | Real estate | 2023 |
| Kieser Medical Corporation Ltd | Information & communication | 2020 |
| Kiest Limited | Health & social care | 2013 |
| Kilda Ltd | Professional & scientific | 2009 |
| Kilkenny & Gomm Developments Ltd | Construction | 2004 |
| Kilkenny & Gomm Limited | Construction | 2002 |
| Kimberley (Oxford) Limited | Administrative & support | 1983 |
| Kimiyuni Ltd | Wholesale & retail | 2026 |
| Kimja Limited | Education | 2024 |
| Kina Ceramics Ltd | Manufacturing | 2024 |
| Kinder Creative Ltd | Professional & scientific | 2023 |
| Kinderton Trustees Limited | Administrative & support | 2000 |
| Kindness Collective Limited | Manufacturing | 2017 |
| Kinetic DOC Ltd | Health & social care | 2025 |
| Kinetix Corporate Finance LLP | | 2010 |
| Kingfisher Financial Management Ltd | Financial services | 2018 |
| Kingfisher Gardens Limited | Administrative & support | 2024 |
| Kingspool Limited | Construction | 2017 |
| Kingston Court Residents Association (Oxford) Limited | Households | 1972 |
| Kingsway Court (Kidlington) Management Company Limited | Households | 1974 |
| Kingswood Accountancy Services Ltd | Professional & scientific | 2004 |
| Kintsugi Consulting Ltd | Professional & scientific | 2019 |
| Kinwealth Limited | Financial services | 2024 |
| Kirkdesigns Limited | Information & communication | 2011 |
| Kiron Associates Ltd | Administrative & support | 2017 |
| Kirone Limited | Real estate | 2000 |
| KIT Accounts Ltd | Professional & scientific | 2014 |
| KIT Mobility Taxis Oxford Ltd | Transport & logistics | 2018 |
| Kitala Properties Limited | Construction | 2026 |
| Kitchen Architecture Contracts Limited | Extraterritorial | 2014 |
| Kitchen Architecture Limited | Wholesale & retail | 2002 |
| Kite Architects Limited | Professional & scientific | 2025 |
| Kite Development & Consulting Limited | Information & communication | 2012 |
| Kite Event Consultancy Limited | Professional & scientific | 2020 |
| Kiteng Services Ltd | Other services | 2021 |
| Kivu International Foundation | Professional & scientific | 2021 |
| Kivu International Ltd | Professional & scientific | 2015 |