| C-Engineering, spol. s r.o. | |
| C.G.C., a.s. | |
| C2i, s.r.o. | |
| CAD systémy | Banská Bystrica |
| Calcurates | |
| CanTechnology | |
| Cassovia Code | |
| CB ESPRI | |
| Central European Education Institute, s.r.o. | |
| Centrum vedecko-technických informácií Slovenskej republiky | |
| Chillix | |
| Ckomplet, s.r.o. | Prešov |
| CLEX File Manager | Bratislava |
| Clinitria Ltd | |
| CloudTalk | |
| CMD, s.r.o. | Bratislava |
| Cofidis Slovakia | |
| Collage of International Business ISM Slovakia | |
| ColosseoEAS, a.s. | |
| Comcas, s.r.o. | Prešov |
| Comenius University - Department of Applied Mathematics and Statistics | Bratislava |
| ComErgon, s.r.o. | Bratislava |
| Comixu, spol. s r.o. | Nitra |
| Commercium, spol. s.r.o. | |
| Commodity, s.r.o. | |
| CompAct spol. s.r.o. | |
| CompTel.sk | Trnava |
| Computer ABC, s.r.o. | Nitra |
| Computer Club | Nitra |
| Conelec, s.r.o. | |
| Connect Coworking | |
| Consilium Consulting, s.r.o. | |
| ConsultOne, s.r.o. | Bratislava |
| ControlSystem, s.r.o. | |
| CoverPage | |
| CPD Systems Slovakia, s.r.o. | |
| CPP trade, a.s. | |
| CQ servic e, spol. s r.o. | |
| CRAP, s.r.o. | Bratislava |
| CREA.TIFF studio | Trnava |
| CREATE SK, s.r.o. | Žilina |
| Creative Sites | Bratislava |
| Creative Studio, s.r.o. | |
| Crescendo Web Agency | |
| Crowdberry | |
| Crystal Consulting, s.r.o. | |
| Crystal Group, s.r.o. | Trenčín |
| ČSOB | |
| Cubetech, s.r.o. | |
| Čulen a Partner, s.r.o. | |