| Chilworth Estates Services Ltd | Real estate | 2015 |
| Chimclear Chimney Services Limited | Construction | 2014 |
| Chocolate Mechanics Ltd | Wholesale & retail | 2021 |
| Cholsey Great Barns Limited | Real estate | 2001 |
| Choosing Red CIC | Education | 2026 |
| Chorus Life Ltd | Other services | 2026 |
| Chris Elgood Associates Limited | Professional & scientific | 1972 |
| Chris Tubb Building Services Limited | Construction | 2009 |
| Christchurch Tyres Limited | Extraterritorial | 2006 |
| Christie Estates (North) Limited | Extraterritorial | 2007 |
| Christie Estates Southern Limited | Real estate | 1995 |
| Christina Relf Ltd | Professional & scientific | 2003 |
| Christina Rhodes Ltd | Professional & scientific | 2019 |
| Christopher Jones Wealth Management Ltd | Financial services | 2020 |
| Chrysalis Design & Build Ltd | Construction | 2009 |
| Chunkzino Holdings Ltd | Financial services | 2023 |
| Chunkzino Ltd | Information & communication | 2019 |
| Churchbarn Residents Association Limited | Households | 1997 |
| Churches Together in Winchester Limited | Other services | 2023 |
| Chute Farms Limited | Agriculture & fishing | 1939 |
| Chuwee Bubble Limited | Wholesale & retail | 2020 |
| Cinextra Limited | Professional & scientific | 2009 |
| Circle 8 Holdings Limited | Professional & scientific | 2003 |
| Circus Futures | Arts & recreation | 2011 |
| Circus Gallery Ltd | Wholesale & retail | 2022 |
| Cislunar Limited | Information & communication | 2021 |
| Citrus Coaching Ltd | Professional & scientific | 2011 |
| City Broking Limited | Administrative & support | 2010 |
| City Business Centre Winchester (Management) Limited | Real estate | 1987 |
| City Chase Limited | Households | 1980 |
| City Curry Limited | Hospitality | 2024 |
| City Enterprise 17 Limited | Real estate | 2014 |
| City Kebab Winchester Ltd | Hospitality | 2025 |
| City South Life Management Limited | Real estate | 2007 |
| Citygate Commercial Finance Limited | Financial services | 2021 |
| Citygate Mortgages Limited | Financial services | 2020 |
| Cjay America Limited | Wholesale & retail | 2025 |
| Cjay Skincare Ltd | Wholesale & retail | 2025 |
| CJS Inspired Design Limited | Administrative & support | 2005 |
| CK Blades Holdings Limited | Real estate | 2025 |
| Ckir Consulting Limited | Professional & scientific | 2023 |
| Claire Corrie PR Limited | Professional & scientific | 2014 |
| Claisse Estates Limited | Real estate | 2024 |
| Clapton Construction Services Limited | Construction | 2018 |
| Clare's Accounts Ltd | Professional & scientific | 2014 |
| Clarify Training Limited | Education | 2003 |
| Clarke Enterprises (Winchester) Limited | Real estate | 2016 |
| Clarke Saunders Associates Limited | Professional & scientific | 2019 |
| Clarke Trustees NO. 1 Limited | Extraterritorial | 2010 |
| Clarke Trustees NO. 2 Limited | Extraterritorial | 2010 |
| Clarkes of Bowley Limited | Agriculture & fishing | 2016 |
| Class 1 DRY Cleaners Ltd | Other services | 2025 |
| Class 1 Group Ltd | Financial services | 2025 |
| Classic Auction Assistance Ltd | Wholesale & retail | 1998 |
| Classic Stationers Limited | Professional & scientific | 2022 |
| Classmaxi Developments (Solstice) Ltd | Construction | 2022 |
| Classmaxi Limited | Real estate | 2000 |
| Clausentum Limited | Professional & scientific | 2012 |
| Claverdon Ltd | Professional & scientific | 2021 |
| Clayfield Park Homes Limited | Wholesale & retail | 1963 |
| Clayton Cragg Limited | Information & communication | 1999 |
| Clean Extreme Ltd | Administrative & support | 2013 |
| Clearly Beau Ltd | Manufacturing | 2025 |
| Clelland Marketing Limited | Professional & scientific | 2012 |
| Clements Engineering Ltd | Manufacturing | 2024 |
| Cleva Solutions Limited | Professional & scientific | 2018 |
| Clevedale Management Company Limited | Real estate | 2008 |
| Clever Digital Stuff Limited | Information & communication | 2016 |
| Click ROI Ltd. | Information & communication | 2017 |
| Clicka Servicing Company Limited | Administrative & support | 2025 |
| Cliff Lewis Ltd | Real estate | 2020 |
| Clifton Fabrications Limited | Construction | 2013 |
| Cliftons Projects Limited | Professional & scientific | 2014 |
| Climate Sense Limited | Professional & scientific | 2009 |
| Climate Smart Infrastructure Limited | Professional & scientific | 2020 |
| Climate-Smart Infrastructure Partners Limited | Professional & scientific | 2023 |
| Clinical Technology Consultants Ltd | Professional & scientific | 2014 |
| Clique Circularity Ltd | Other services | 2024 |
| Clivedale Commercial Limited | Financial services | 1963 |
| Clock House Southern Limited | Professional & scientific | 2013 |
| Clockword Limited | Construction | 2004 |
| Close Resource Management Limited | Administrative & support | 2005 |
| Cloud Eco Monitoring Limited | Professional & scientific | 2018 |
| Cloud Monitoring Limited | Professional & scientific | 2018 |
| Cloudwin Ltd | Professional & scientific | 2012 |
| Club Clean Pro Ltd | Administrative & support | 2024 |
| Clue Capers Limited | Administrative & support | 2015 |
| Clumber Trustee Company Limited | Other services | 2005 |
| Clyhurst Properties Limited | Extraterritorial | 1973 |
| CMC Motor Company Fareham Limited | Wholesale & retail | 2024 |
| CMF Estates Ltd | Construction | 2021 |
| CMH Privacy & AI Governance Consultancy Services Ltd | Financial services | 2025 |
| CMW Professional Services Ltd | Professional & scientific | 2025 |
| CNC Window Cleaning Ltd | Other services | 2014 |
| Coach Callum Limited | Arts & recreation | 2024 |
| Coach House (NO. 5) LP | | 2015 |
| Coach House Appraisals Litigation Limited Partnership | | 2014 |
| Coach House DSC (NO 3) Limited | Professional & scientific | 2017 |
| Coach House DSC (NO 4) Limited | Professional & scientific | 2020 |
| Coach House DSC (NO 5) Limited | Professional & scientific | 2020 |