| Cayetano Gaming | Sofia |
| CCG Profiles | Sofia |
| Centillion Ltd | Sofia |
| Centio #Cybersecurity | Sofia |
| Centio Shop | Sofia |
| CEO Angels Club | Sofia |
| Changex | Sofia |
| Chaos Software | Sofia |
| Chase A Cloud | Sofia |
| Childish.eu | Sofia |
| CIS Ltd | Sofia |
| CleanTech Bulgaria | Sofia |
| Clearware | Sofia |
| Clientric Академия за Иновации в туризма | Sofia |
| Cloud Office | |
| Cloudcart | Sofia |
| CloudHostSpace Ltd | Sofia |
| ClouDNS | Sofia |
| CloudSource | Sofia |
| Cloxy Ltd | Sofia |
| Cluster Sofia Knowledge City | Sofia |
| CM2W | Sofia |
| CNSys plc | Sofia |
| Code Monsters | Sofia |
| Code Runners | Sofia |
| Codecover | Sofia |
| Codexio Ltd | |
| Coherent Labs | Sofia |
| Colibra | Sofia |
| Colibri ERP | Sofia |
| CoLumbo | |
| Comac Medical Ltd | Sofia |
| Comel Soft Multimedia Ltd | Sofia |
| Commission for Personal Data Protection | Sofia |
| ComNet | Sofia |
| Complete Cloud Solutions Ltd | Sofia |
| Computer 2000 | Sofia |
| Computer Security Services | Sofia |
| Computerworld.bg | Sofia |
| ComSoft Ltd | Sofia |
| Concept Digital | Sofia |
| Connect Me | |
| Connect2id Ltd | |
| ConvertHub | |
| Coolbox | Sofia |
| Corpus | Sofia |
| Coshare HIVE | Sofia |
| Costimize Ltd | |
| Council for Electronic Media | |
| Craftberry | |