| Colsys, s.r.o. | |
| Com-Sys TRADE, spol. s r.o. | |
| Comfor Stores, a.s. | South Moravian |
| Comfort Space, a.s. | |
| Comin.cz, s.r.o. | Prague |
| Comlinks, s.r.o. | Prague |
| Commerzbank v České republice | Prague |
| Compas automatizace, spol. s r.o. | Vysočina |
| COMPEKON, s.r.o. | Olomouc |
| Complet, a.s. | Prague |
| Comprimato Systems, s.r.o. | |
| Compunax, spol. s r.o. | |
| CompuNet, s.r.o. | |
| Compureg Plzeň, s.r.o. | |
| Computer Help, spol. s r.o. | |
| Computer System Group, a.s. | |
| Computer Systems Consulting, s.r.o. | Prague |
| Computerworld CZ | Prague |
| ComSTAR, spol. s r.o. | Prague |
| CoNet, s.r.o. | |
| ContextMinds, s.r.o. | |
| ControlTech, s.r.o. | Central Bohemian |
| Coolhousing.net | Prague |
| CoolPeople Czech, s.r.o. | Prague |
| COPIA LIBEREC, s.r.o. | Liberec |
| Coprosys | |
| Coworking Mitrovski | |
| Crazy Boomerang Software | South Moravian |
| CRC Data, spol. s r.o. | |
| Creanet, s.r.o. | |
| Creative Dock | |
| Creative Studio | Plzeň |
| Credo Ventures | Prague |
| Creepy, s.r.o. | Zlín |
| Crispy Apps, s.r.o. | |
| Crux consulting, s.r.o. | |
| CS SOFT, a.s. | |
| CS24, s.r.o. | Prague |
| Csaba Botoš | Pardubice |
| CTIT | |
| CTY Group, a.s. | |
| Cube CZ, s.r.o. | Liberec |
| CUE, a.s. | Prague |
| Cyber Fox | Prague |
| Cyber Stream Technology | South Moravian |
| CyberS, s.r.o. | Prague |
| Cybersales, a.s. | Prague |
| Cybersecurity Help, s.r.o. | |
| CyberSecurity.CZ | |
| CyberSoft, s.r.o. | Moravian-Silesian |