| CHA Biotech | Gyeonggi |
| CHAI Corporation | Seoul |
| Changsoft i&i | Seoul |
| Changwon Moonsung University | South Gyeongsang |
| Childly Corporation | Seoul |
| Chong Kun Dang Holdings Corporation | |
| Chongshin University | Seoul |
| Chosun Nursing College | |
| Christian College of Nursing | |
| Chung-Ang University | Seoul |
| Chung-Ang University - School of Computer Science and Engineering | Seoul |
| Chungnam National University | |
| Chungnam State University | |
| Chungnam Technopark | South Chungcheong |
| Ciper Electronics Co., Ltd | Seoul |
| CIS Corporation | Gyeonggi |
| CITECH | Seoul |
| Cizion | |
| CJ Bioscience, Inc. | Seoul |
| CJ OliveNetworks Co., Ltd | Seoul |
| Classys, Inc. | |
| Cloubot | Seoul |
| Clover Games | Seoul |
| CM Tech Semiconductor Parts | Gyeonggi |
| CMCTech | Seoul |
| CMG Pharm Co., Ltd | Gyeonggi |
| CMITech Co., Ltd | Gyeonggi |
| CNT Electronics Co., Ltd | Seoul |
| Cocktail Cloud | Seoul |
| CocoaSoft Co., Ltd | Seoul |
| Code States Co., Ltd | Seoul |
| Codeground | Seoul |
| Codeit Co., Ltd | Seoul |
| Codemind Corporation | Daegu |
| CodeSquad | Seoul |
| Coding Dojang | Seoul |
| Coinone Co., Ltd | Seoul |
| Collab Asia | |
| Com2uS Group | Seoul |
| Com2Verse Corporation | Seoul |
| COMA Technology Co., Ltd | North Gyeongsang |
| Comake Corporation | Seoul |
| Combustech | Seoul |
| COMMAX | Gyeonggi |
| Common Computer, Inc. | |
| Company K Partners | Seoul |
| Comtec Systems Co., Ltd | Seoul |
| CookApps | Gyeonggi |
| Coolidge Corner Investment | Seoul |
| CoolMessenger | Seoul |