| CTF Computerhaus | Bavaria |
| CTI Consulting AG | Hesse |
| CTI New Media GmbH | Berlin |
| CTK Computer Technik Kress | |
| CTM Computer Technik Marketing GmbH | Bremen |
| CTM-COM GmbH | Hesse |
| CTO Software GmbH | North Rhine-Westphalia |
| cts GmbH | Bavaria |
| Cube Biotech GmbH | North Rhine-Westphalia |
| Cube Optics AG | Rhineland-Palatinate |
| Cuesoft GmbH | Baden-Württemberg |
| Cult Consult | Bavaria |
| Cultured Code GmbH & Co. KG | |
| Cultuzz Digital Media GmbH | Berlin |
| Cumin GmbH | Berlin |
| CUP GmbH | Baden-Württemberg |
| Cura-Soft Pflegesoftware GmbH | |
| Cure Digital Finance GmbH | |
| CURE GmbH | |
| Cure53 | |
| CUREosity GmbH | |
| CureVac SE | |
| Curexsys GmbH | |
| Curio Systems GmbH | Bavaria |
| Curiosity GmbH | |
| Curious Capital | North Rhine-Westphalia |
| cursorsystems GmbH | Berlin |
| Cusp Capital Partners | North Rhine-Westphalia |
| Custify | |
| Customcells Itzehoe GmbH | |
| Customer Alliance GmbH | |
| CVC Revenue Solutions GmbH | |
| CVOsite GbR | Lower Saxony |
| CVS Ingenieurgesellschaft mbH | Bremen |
| CVW-Privatbank AG | |
| CWA GmbH | Lower Saxony |
| CWK IT Consulting GmbH | Baden-Württemberg |
| CWS Computer & Webservices | Berlin |
| cxomni GmbH | |
| Cyanite.ai | |
| Cybay New Media GmbH | Lower Saxony |
| Cyber-Sicherheitsrat Deutschland e.V. | |
| Cyber.Core | Lower Saxony |
| Cyberday GmbH | Bavaria |
| CyberDesk GmbH | |
| Cyberlab GmbH | Berlin |
| Cyberpromote GmbH | Bavaria |
| cyberTECHNOLOGIES GmbH | |
| cyberwebhosting.de | Hamburg |
| Cybox GmbH | Lower Saxony |