| Copying Centre Limited(The) | Manufacturing | 1984 |
| Corbett Farming Limited | Agriculture & fishing | 2016 |
| Corby Tyres and Exhausts Limited | Extraterritorial | 2010 |
| Core Aviation Network Ltd | Manufacturing | 2024 |
| Corinthian Court Residents Limited | Households | 2002 |
| Corium Consulting Limited | Professional & scientific | 2024 |
| Cork Holiday Homes Limited | Real estate | 2016 |
| Corner House Eastergate Limited | Households | 2007 |
| Cornerstone USA Limited | Real estate | 2024 |
| Cornish Origins Ltd | Financial services | 2025 |
| Cornish Rose Company Limited | Wholesale & retail | 2000 |
| Cornucopia Accountants Ltd. | Professional & scientific | 2020 |
| Corporate Horse Limited | Administrative & support | 2007 |
| Corporation Holdings Ltd | Manufacturing | 2013 |
| Corsini Investments Limited | Professional & scientific | 2024 |
| Corvus Project Solutions Ltd | Professional & scientific | 2024 |
| Costello Technologies Ltd | Information & communication | 2015 |
| Costsecure Limited | Professional & scientific | 1994 |
| Cotswold Riding Opportunities Project CIC | Arts & recreation | 2019 |
| Coudre Ltd | Manufacturing | 2014 |
| Country Cures (Pest Control) Limited | Agriculture & fishing | 1998 |
| Country Oak Buildings Limited | Construction | 2015 |
| Country Retreats Ltd | Real estate | 2002 |
| Countryside Solutions Limited | Agriculture & fishing | 1999 |
| Countrywide Medical Selection Limited | Administrative & support | 2022 |
| Covermarque Limited | Financial services | 2003 |
| Covoxa Limited | Information & communication | 2010 |
| COX & Sons Property Limited | Other services | 2026 |
| Coxford Down Cattery Limited | Other services | 2013 |
| CP (UKI) Ltd | Information & communication | 2018 |
| Crabtech Ltd | Information & communication | 2018 |
| Craddock Building Services Ltd | Construction | 2015 |
| Craftbox Media Ltd | Information & communication | 2007 |
| Cragg Carbon Solutions Ltd | Manufacturing | 2025 |
| Cranbourne Consultancy Ltd | Information & communication | 2018 |
| Cranburys Holdings Ltd | Real estate | 2022 |
| Cranworth Developments Ltd | Construction | 2018 |
| Creative Design & Build (Hampshire) Ltd | Construction | 2012 |
| Creative Facade Design Ltd | Administrative & support | 2016 |
| Creative Flora Ltd | Arts & recreation | 2017 |
| Credent Advisory Limited | Professional & scientific | 2023 |
| Cresbee Court Management Company Limited | Households | 2006 |
| Crestblue Limited | Real estate | 2006 |
| Crestel Contractors (Southern) Limited | Construction | 1972 |
| Crew Create Ltd | Information & communication | 2025 |
| Cribb Tyre & Battery Ltd | Extraterritorial | 2002 |
| Cribba Limited | Administrative & support | 2023 |
| Cricket Hoppers Limited | Education | 2025 |
| Cripstead Financial Limited | Professional & scientific | 2023 |
| Crmsquad Limited | Professional & scientific | 2024 |
| Crop Management Partners LLP | | 2006 |
| Cross Country Engineering (1987) Limited | Manufacturing | 1987 |
| Cross Keys International Dressage Horses Limited | Professional & scientific | 2022 |
| Cross Laminated Timber Solutions Ltd | Construction | 2026 |
| Cross Valley Milk Ltd | Manufacturing | 2021 |
| Crouch & Cole Developments Ltd | Construction | 2025 |
| Crouch Construction Services Limited | Construction | 2021 |
| Crowded Outlet Ltd | Wholesale & retail | 2013 |
| Crowned Impala Communications Limited | Professional & scientific | 1999 |
| Crowvale Securities (Romsey Road) Ltd | Real estate | 2019 |
| Crux Easton (Farms) Limited | Professional & scientific | 1958 |
| Crystal Clean Interior Ltd | Administrative & support | 2023 |
| Crystal Clear Designs and Signs Ltd | Manufacturing | 2006 |
| CS Automotive Consultants Limited | Wholesale & retail | 2002 |
| CS Enterprises Holding Limited | Wholesale & retail | 2025 |
| CS Winchester Limited | Hospitality | 2019 |
| CSR Certification Ltd | Other services | 2019 |
| CSS Developments Limited | Construction | 2005 |
| CTW Associates Limited | Professional & scientific | 2005 |
| Cubes&Boxes Limited | Real estate | 2023 |
| Culture of Care Ltd | Education | 2017 |
| Curlyfox Limited | Other services | 2023 |
| Curzon African Holdings Limited | Financial services | 2017 |
| Curzon Holdings Limited | Financial services | 2017 |
| Curzon Resources Limited | Administrative & support | 2014 |
| Cuthbert Ward | | 1994 |
| Cuthbert Ward | | 1996 |
| Cutler & Partners Ltd | Construction | 2025 |
| CV Writers Limited | Administrative & support | 2011 |
| CY Sheet Metal Limited | Manufacturing | 2009 |
| Cycling Dragon Limited | Administrative & support | 2014 |
| D and D Craftsmen Ltd | Construction | 2021 |
| D Collinson Consulting Limited | Agriculture & fishing | 2019 |
| D F Ranger & Sons Ltd | Transport & logistics | 2011 |
| D G 206 Limited | Professional & scientific | 2007 |
| D G Biles Ltd | Construction | 2022 |
| D Hobbs & Sons LLP | | 2014 |
| D J Hannu Limited | Arts & recreation | 2002 |
| D Stevenson Limited | Real estate | 2022 |
| D T Electricians Ltd | Construction | 2020 |
| D&B Electrical Contractors Ltd | Energy | 2013 |
| D&D Property Services (Winchester) Limited | Real estate | 2014 |
| D&Z Acoustic Limited | Wholesale & retail | 2019 |
| D-Id Limited | Professional & scientific | 2014 |
| D. Barker & SON Ltd | Manufacturing | 2012 |
| D.A. Associates (Winchester) Ltd | Professional & scientific | 2022 |
| D.L. Enterprises Limited | Real estate | 1984 |
| D.L.E. Services Limited | Real estate | 1983 |
| D1LON Limited | Arts & recreation | 2020 |
| Dakota Estates Investments Limited | Real estate | 2025 |