| Com-et Mediadesign | Hesse |
| COM-IN Telekommunikations GmbH | Bavaria |
| COM.lounge GmbH | North Rhine-Westphalia |
| com2m GmbH | |
| coma2 e-branding | Bavaria |
| Combase AG | Saxony |
| Combit | Baden-Württemberg |
| Combyne GmbH | Bavaria |
| COMCEPT GmbH | North Rhine-Westphalia |
| ComCept GmbH – Netzwerke und Kommunikation | Baden-Württemberg |
| ComConnect Kommunikationssysteme GmbH | Rhineland-Palatinate |
| ComConsult GmbH | North Rhine-Westphalia |
| Comdatec GmbH | Baden-Württemberg |
| Comdirect | |
| come-to-web | Hesse |
| come2as media | Hesse |
| Comeco GmbH & Co. KG | |
| Comelio GmbH | Berlin |
| Cometum GmbH | |
| Comexio GmbH | Rhineland-Palatinate |
| Comforte AG | Hesse |
| COMfuture Computer- und Kommunikationssysteme GmbH | Saxony |
| ComfyLight GmbH | |
| COMHAIR GmbH | Lower Saxony |
| Comitatus Software AG | Berlin |
| Comito Solutions GmbH | |
| COMIX Software GmbH | Bavaria |
| Comline Elektronik Elektrotechnik GmbH | Bavaria |
| Comma Soft AG | North Rhine-Westphalia |
| Commercetools GmbH | |
| Commerz Ventures GmbH | Hesse |
| Commerzbank AG | Hesse |
| CommitWork GmbH | North Rhine-Westphalia |
| Common Sense Consulting GmbH | |
| Common Sense Intelligence GmbH | |
| Common Vision Blox | Bavaria |
| Common-Link AG | Baden-Württemberg |
| Commsult | Brandenburg |
| commsult AG | |
| Communardo Software GmbH | Saxony |
| Communication Services Tele2 GmbH | North Rhine-Westphalia |
| Communication Systems GmbH | |
| Communicators GmbH & Co. KG | |
| Community4you GmbH | Saxony |
| comNET - Gesellschaft für Kommunikation + Netzwerke mbH | Lower Saxony |
| ComNet GmbH | North Rhine-Westphalia |
| Como Consult GmbH | |
| Comp&Phone EDV- und Kommunikationssysteme GmbH | Baden-Württemberg |
| COMP-MALL Computer-Vertriebs GmbH | Bavaria |
| COMP.Net GmbH | |