| Chislebury Educational Services Limited | Administrative & support | 2020 |
| Chitchens Ltd | Information & communication | 2022 |
| Chloe Wood Garden Design Ltd | Administrative & support | 2021 |
| Chocolate Meadow Limited | Professional & scientific | 2012 |
| Chofard Enterprise Ltd | Wholesale & retail | 2020 |
| Cholesbury Farming Ltd | Real estate | 2026 |
| Chopra and Sons Edgware Ltd | Wholesale & retail | 2024 |
| Chopsticks Canterbury Limited | Hospitality | 2006 |
| Chopsticks Restaurants Limited | Hospitality | 2003 |
| Chos Chap Limited | Real estate | 2026 |
| Chown Enterprise Limited | Financial services | 2013 |
| Chris Andrews Publications Ltd. | Administrative & support | 2007 |
| Chris East Trading Limited | Wholesale & retail | 2001 |
| Chris Lewis Fire & Security (South) Limited | Extraterritorial | 1986 |
| Chris Little Ltd | Real estate | 2017 |
| Chris Orme Commercial Growth Ltd | Professional & scientific | 2023 |
| Chrisco Ministries UK | Other services | 2002 |
| Christ Grace and Life Church Ltd | Other services | 2024 |
| Christ Logistics Ltd | Administrative & support | 2016 |
| Christ M Trade Ltd | Transport & logistics | 2017 |
| Christensen ET AL Limited | Real estate | 2020 |
| Christiansen Properties Limited | Real estate | 2018 |
| Christie LET Ltd | Real estate | 2025 |
| Christina's Cleaners Ltd | Administrative & support | 2023 |
| Christopher Bishop Consulting Limited | Information & communication | 2024 |
| Chronex Global Solutions Ltd | Information & communication | 2025 |
| Chrysol Ventures Limited | Health & social care | 2020 |
| Chrysolite Communications Ltd | Professional & scientific | 2024 |
| Chukaaaron Boutique Limited | Health & social care | 2015 |
| Chunk’D Ltd | Manufacturing | 2025 |
| Church Farm (Apartment Block) Management Company Limited | Households | 2025 |
| Church Farm (West Hanney) Management Company Limited | Real estate | 2016 |
| Church Farm Industries Ltd | Professional & scientific | 2015 |
| Church Mission Society | Other services | 2009 |
| Church Missionary Trust Association Limited | Extraterritorial | 1913 |
| Church of Fire and Revival Ltd | Other services | 2023 |
| Churchill Court (2007) Limited | Households | 2007 |
| Churchill Court (Oxford) Management Company Limited | Households | 2005 |
| Churchill Property Solutions PLO Ltd | Real estate | 2020 |
| Chyinghpaw Ltd | Manufacturing | 2024 |
| Cibaku Build & Refurb Ltd | Construction | 2023 |
| Cibus Health Ltd | Health & social care | 2019 |
| Cicada Consulting Ltd | Information & communication | 2009 |
| Cico Solutions Ltd | Administrative & support | 2021 |
| Cinainvest UK Limited | Professional & scientific | 2016 |
| Cinderella's Cleaning Services (Oxford) Limited | Other services | 2004 |
| Cineprolab Ltd | Information & communication | 2025 |
| Cinnamon Properties Limited | Real estate | 2025 |
| Cios Beacon SPV Limited | Financial services | 2026 |
| Circadian Therapeutics Limited | Health & social care | 2016 |
| Circpro (UK) Limited | Wholesale & retail | 2020 |
| Circular Crafts Ltd | Wholesale & retail | 2026 |
| Circus Arts Academy | Education | 2001 |
| Cirencester Hand Carwash Ltd | Administrative & support | 2019 |
| Cirruz Ltd | Manufacturing | 2019 |
| CIS Healthcare Limited | Financial services | 2006 |
| CIS Oncology Limited | Information & communication | 1989 |
| Citadel Ltd | Administrative & support | 2018 |
| Citrine Flamingo Ltd | Professional & scientific | 2024 |
| Citrine International Tax Limited | Professional & scientific | 2014 |
| City & Beyond Ltd | Administrative & support | 2023 |
| City College Oxford Group Ltd | Education | 2024 |
| City College Oxford Limited | Education | 2012 |
| City Insights (London) Limited | Information & communication | 2009 |
| City Logistics and Motors Ltd | Other services | 2025 |
| City of Oxford Orchestra Limited | Arts & recreation | 2010 |
| City of Oxford Society of Model Engineers Limited | Arts & recreation | 1996 |
| CIV Ventures Ltd | Information & communication | 2026 |
| Civitas Primos Ltd | Wholesale & retail | 2019 |
| Civity Holdings Limited | Financial services | 2022 |
| Civity Land Limited | Real estate | 2022 |
| Civity Limited | Professional & scientific | 2022 |
| CJP (Great Missenden) Ltd | Real estate | 2023 |
| CJP Construction Services Limited | Real estate | 2007 |
| CJR Engineering Services Ltd | Professional & scientific | 2019 |
| Cjwd Group Ltd | Manufacturing | 2025 |
| Ckanta Ltd | Manufacturing | 2022 |
| Ckinvestors Ltd | Real estate | 2020 |
| Claire Jacques Consulting Services Ltd | Health & social care | 2022 |
| Claire Michelle Buckett Limited | Extraterritorial | 2022 |
| Clan Cleaning Ltd | Administrative & support | 2025 |
| Clanpower Limited | Wholesale & retail | 2000 |
| Clapham Apartments Limited | Real estate | 2023 |
| Clareant Fertility Treatments Limited | Financial services | 2023 |
| Clarendon International Education Limited | Education | 1994 |
| Clarendon Square Construction Limited | Construction | 2025 |
| Clarity Strategy Limited | Administrative & support | 2012 |
| Clarke Properties Oxford Ltd | Real estate | 2019 |
| Clarkes Products (Weyhill) Limited | | 1979 |
| Clarkewoodplitt Limited | Administrative & support | 2021 |
| Clarks(Wantage),Limited | Manufacturing | 1908 |
| Clarkson's Holdings Ltd | Financial services | 2019 |
| Clarus Communications Limited | Information & communication | 2022 |
| Classic Cleaners Oxford Limited | Administrative & support | 2021 |
| Classic Equitation LLP | | 2024 |
| Classic Ringtones Limited | Information & communication | 2004 |
| Classic Saloon Car Club (Great Britain) Limited | Arts & recreation | 1992 |
| Classical Concerts Limited | Information & communication | 2016 |
| Classique Bedrooms Ltd. | Manufacturing | 2010 |
| Classy Barbers Oxford Ltd | Other services | 2024 |