| Cloudstor Limited | Information & communication | 2022 |
| CLV Properties Limited | Real estate | 2021 |
| CM Martial Arts Ltd | Education | 2024 |
| CMM Capital Limited | Professional & scientific | 2014 |
| CMY Properties Limited | Real estate | 2021 |
| CN Aviation Services Ltd | Manufacturing | 2021 |
| Coconut Lane Ltd. | Wholesale & retail | 2015 |
| Cocopup Ltd | Manufacturing | 2020 |
| COD Marketing Limited | Professional & scientific | 2024 |
| Codco Limited | Real estate | 2018 |
| Codsall Fleet Maintenance Limited | Wholesale & retail | 2020 |
| Cogges Electrical Ltd | Construction | 2017 |
| Cogges Energy Limited | Construction | 2026 |
| Cogges Heritage Enterprises Limited | Arts & recreation | 2013 |
| Cogges Heritage Trust | Arts & recreation | 2010 |
| Cogges Joinery Limited | Construction | 2015 |
| Cognitive Communications Strategy & Tactics Limited | Financial services | 2026 |
| Cohen Management Consulting Limited | Professional & scientific | 2014 |
| Cokethorpe Enterprises Limited | Administrative & support | 2024 |
| Colbert Wall Trading Limited | Construction | 2020 |
| Cold Planing Ltd | Water & waste | 2014 |
| Coldray Limited | Hospitality | 1971 |
| Coleman Architecture Limited | Professional & scientific | 2010 |
| Collab Films Ltd | Information & communication | 2019 |
| COLLAB4CHANGE Ltd | Professional & scientific | 2025 |
| Collected Pros Limited | Professional & scientific | 2014 |
| Collective Support Limited | Manufacturing | 2012 |
| Collin Medico-Legal Ltd | Health & social care | 2010 |
| Colliss & Quinton Limited | Arts & recreation | 2008 |
| Combe Community Hub | Real estate | 2016 |
| Combe Gate Management Company Limited | Households | 1986 |
| Combined Technologies (Oxfordshire) Limited | Information & communication | 2008 |
| Commercial Coffee Machines Limited | Extraterritorial | 2013 |
| Common Grind Limited | Hospitality | 2015 |
| Comms for Schools Limited | Professional & scientific | 2021 |
| Comms&Co. Ltd | Administrative & support | 2009 |
| COMMS4U Ltd | Information & communication | 2020 |
| Communications 4U Limited | Information & communication | 2017 |
| Communications Hive Ltd | Professional & scientific | 2026 |
| Community First Oxfordshire | Health & social care | 1990 |
| Complete Inspection & Surveys Limited | Professional & scientific | 2013 |
| Complete Inspection Services Limited | Administrative & support | 2004 |
| Complete Inspection Surveyors Ltd | Construction | 2019 |
| Complete Ions Limited | Manufacturing | 2003 |
| Complete Rally Services Limited | Other services | 2016 |
| Completely Cotswolds Ltd | Hospitality | 2022 |
| Completion Limited | Professional & scientific | 2006 |
| Compmath.Ai Limited | Professional & scientific | 2023 |
| Computerbasedmath.Org Ltd | Education | 2012 |
| Conceptsworld Properties and Investments Ltd | Real estate | 2021 |
| Concours Carpets Limited | Manufacturing | 2021 |
| Connect Business Services Limited | Administrative & support | 2024 |
| Connect Neurotherapy Services Limited | Health & social care | 2018 |
| Connect Oxford Ltd | Professional & scientific | 2008 |
| CONNECT4OXFORDSHIRE Ltd | Information & communication | 2025 |
| Connection Data Limited | Information & communication | 2022 |
| Connie's Collective Limited | Arts & recreation | 2025 |
| Connie's Costumes Limited | Wholesale & retail | 2021 |
| Consertix Ltd | Information & communication | 2018 |
| Console Repair LAB Limited | Other services | 2021 |
| Construpack Ltd | Construction | 2021 |
| Consulting for Development Ltd | Professional & scientific | 2016 |
| Contact Plates Ltd | Wholesale & retail | 2024 |
| Continental Crayfish Limited | Agriculture & fishing | 2009 |
| Contractor Connection Ltd | Administrative & support | 2023 |
| Conway Property (Bromag) Limited | Real estate | 2024 |
| Conway Property Company (Witney) Limited | Real estate | 2004 |
| Conway Property Holdings Limited | Professional & scientific | 2004 |
| Conygree Development Limited | Construction | 2019 |
| Cook Modelling Limited | Professional & scientific | 1998 |
| Cookietaker Ventures Limited | Financial services | 2022 |
| Cool Cuisine Foodservice Limited | Hospitality | 2006 |
| Cooper and Horne Ltd | Manufacturing | 2025 |
| Cooper Livestock Ltd | Agriculture & fishing | 2024 |
| Cooper Mews Management Company Limited | Professional & scientific | 2006 |
| Copperlimit Limited | Construction | 2010 |
| Copperworks Heating and Plumbing Limited | Construction | 2020 |
| Copyright Witness Limited | Information & communication | 2004 |
| Core Trading UK Ltd | Wholesale & retail | 2025 |
| Corn Barbers Limited | Other services | 2017 |
| Cornbury Property Services Ltd | Real estate | 2026 |
| Cornish Stores Ltd | Wholesale & retail | 2019 |
| Cornmarket Properties Limited | Real estate | 2018 |
| Corran Consulting Ltd | Professional & scientific | 2015 |
| Corus Dent UK Limited | Manufacturing | 2022 |
| Cosmeticeve Ltd | Professional & scientific | 2023 |
| Cotswalls Stone Co Ltd | Construction | 2023 |
| Cotswold Agricultural Construction Limited | Construction | 2024 |
| Cotswold and Bath Cast Stone Ltd | Manufacturing | 2016 |
| Cotswold Artisan Clay Ltd | Manufacturing | 2024 |
| Cotswold Bespoke Carpentry Ltd | Manufacturing | 2019 |
| Cotswold Bike Box Hire Ltd | Administrative & support | 2025 |
| Cotswold Carers Ltd | Health & social care | 2016 |
| Cotswold Clean Home Company Ltd | Administrative & support | 2025 |
| Cotswold Commercial Cleaning Ltd | Administrative & support | 2013 |
| Cotswold Construction Ltd | Construction | 2014 |
| Cotswold Cottage Gems Ltd | Hospitality | 2018 |
| Cotswold Dairy Equipment Company Limited | Manufacturing | 1969 |
| Cotswold Dairy Limited | Financial services | 2021 |
| Cotswold Garden Tea Rooms Ltd | Hospitality | 2012 |