| Comsat Sp. z o.o. | Greater Poland |
| Comset S.A. | Lesser Poland |
| ComSoft Radom | |
| Comtegra S.A. | Masovian |
| Comtronic Sp. z o.o. | Lublin |
| Comzit | Masovian |
| Concept Data S.A. | |
| Conclusive Engineering | |
| Concordia Design | |
| CONET Sp. z o.o. | |
| Confitura | |
| Confly | |
| Conlea Sp. z o.o. | Pomeranian |
| Connect Distribution Sp. z o.o. | Masovian |
| Connecta | Lower Silesian |
| Connecto Sp. z o.o. | |
| ConnectPoint | |
| ConnectPoint Sp. z o.o. | |
| Conor Interactive | Masovian |
| Consdata S.A. | |
| Consonance Sp. z o.o. | Lesser Poland |
| Contact Center Sp. z o.o. | Masovian |
| Contec IT Sp. z o.o. | Masovian |
| Contec Sp. z o.o. | |
| Contellation | |
| Context Sp. z o.o. | |
| Control System FMN Sp. z o.o. | Masovian |
| Controlling Systems Sp. z o.o. | Lower Silesian |
| Convel Sp. J. | Masovian |
| Coolbrand | |
| Copernicus Center | |
| Copix Sp. z o.o. | Masovian |
| Copoint Sp. z o.o. | |
| Cora AI | |
| CorCode | |
| CorCode Sp. z o.o. | |
| Core Logic Sp. z o.o. | |
| CorNet | Pomeranian |
| Correscopy | |
| Corsario.pl | Lower Silesian |
| Cortland | Silesian |
| CosmicWeb Sp. z o.o. | |
| CosmoEye | Lublin |
| CoverNET | Subcarpathian |
| Cowork | |
| Coworking Office 12 | |
| CPU ZETO Sp. z o.o. | Lower Silesian |
| Cracow University of Technology | Lesser Poland |
| Crafton | Greater Poland |
| Craftware | |