| Cafler | Barcelona |
| CAI Sistemas Informáticos, S.L. | Pontevedra |
| Caixa Capital Risc | Balearic Islands |
| Caliboweb | Zaragoza |
| CalidadPrecio | Madrid |
| Call Centrix | Madrid |
| Calus Seguridad, S.L. | Madrid |
| Cámara de Comercio España Israel | |
| Campus Can Ruti | Barcelona |
| Campus Training | A Coruña |
| Camrod Servicios Informáticos, S.L. | Madrid |
| Canaima Marketing | |
| Canal de Comunicaciones Unidas, S.A.U. | Madrid |
| Canal Intro, S.L. | Cáceres |
| CanBuyOn | |
| CancerAppy | |
| Canela Tech, S.L. | Burgos |
| Canon España | Madrid |
| Cap Solutions | Madrid |
| Capital Cell | |
| Capital Cell España | Barcelona |
| Capital Energy | Madrid |
| Capital Privado MB | Barcelona |
| Capri Software | Barcelona |
| Capri Telecom | Madrid |
| Captio | Barcelona |
| Caravelo | |
| Card-Dynamics | Madrid |
| Cardumen Capital SGEIC, S.A. | Madrid |
| CargaTuCoche | Madrid |
| Cargestion | Málaga |
| CARLA | |
| Carlos Blanco | Barcelona |
| Carlos Cuesta | Barcelona |
| Carlos III University of Madrid - Robotics Lab | Madrid |
| Carrie Consulting, S.L. | |
| Cartagon AX Cloud, S.L. | Madrid |
| Cartom Comunicación | Madrid |
| Carts Guru | Barcelona |
| Cartucho.es | Madrid |
| CartuchosTinta | Málaga |
| Carver Advanced Systems, S.L. | |
| Castelor, S.L. | Burgos |
| CastleCRM | Barcelona |
| Casum Properties, S.L. | Barcelona |
| CAT1.net | Barcelona |
| Catimatge, S.L. | Barcelona |
| CATNIX | Barcelona |
| CBO-Marketing | Tarragona |
| CC Soft | Cáceres |