| CodeTwo | Lower Silesian |
| CodeUnion | |
| CodeWave | Lower Silesian |
| Codeweaver Sp. z o.o. | |
| Codewise Sp. z o.o. Sp. k. | Lesser Poland |
| CodeWith Sp. z o.o. | |
| Codibly | |
| Codifive Sp. z o.o. | |
| Codigmatic | |
| Codini Digital | |
| Codino Sp. z o.o. | |
| Codium | |
| Cogitech | |
| Cognitiva | |
| Cognitum | |
| Cognize | |
| COIG S.A. | Silesian |
| Colaborawork.pl | |
| Coldlight Creative | Lesser Poland |
| CoLegal | |
| Collegium Balticum | |
| Collegium Civitas | Masovian |
| Collegium Da Vinci | Greater Poland |
| Collegium Masoviense | |
| Collegium Witelona Uczelnia Państwowa | |
| Columbus Energy S.A. | |
| Comarch S.A. | Lesser Poland |
| Comarch S.A. | |
| Comarch S.A. | |
| ComDevelop | Silesian |
| COMES Sp. z o.o. | Lower Silesian |
| Cometari | Lesser Poland |
| Comex S.A. | Pomeranian |
| Comfortel Sp. z o.o. | |
| Commerce-UI | |
| Commerise | |
| Commoditech | |
| Comp S.A. | Masovian |
| COMP Soft Sp. z o.o. | |
| Comp-Win | Greater Poland |
| CompArt International | Masovian |
| Complex Computers Sp. z o.o. | Świętokrzyskie |
| Complex S.C. | West Pomeranian |
| Comprix | Świętokrzyskie |
| CompuTec S.A. | |
| Computer Group Pakt Sp. J | Masovian |
| Computer Plus Kraków S.A. | Lesser Poland |
| Computer Service Expert | Lower Silesian |
| Computersoft | Lower Silesian |
| Computex | |