| COMMAX | Gyeonggi |
| Common Computer, Inc. | |
| Company K Partners | Seoul |
| Comtec Systems Co., Ltd | Seoul |
| CookApps | Gyeonggi |
| Coolidge Corner Investment | Seoul |
| Coolidge Corner Investment | |
| CoolMessenger | Seoul |
| Corecess Korea, Inc. | Gyeonggi |
| CORESTEMCHEMON, Inc. | Gyeonggi |
| Cosmo-Robotics Co., Ltd | Seoul |
| COUX Design Lab | Seoul |
| Cowon Systems, Inc. | Seoul |
| Cravemob Co., Ltd | Seoul |
| Cream | Seoul |
| Creative Code | Seoul |
| Crevisse Partners Corporation | Seoul |
| Crinity, Inc. | Seoul |
| Cross ENF, Inc. | |
| CROSSCERT | Seoul |
| Crowdworks Co., Ltd | Seoul |
| CRScube Co., Ltd | Seoul |
| Cryptolab Co., Ltd | Seoul |
| Crystal Genomics, Inc. | Seoul |
| CSCAM Co., Ltd | |
| CSE Co., Ltd | |
| CU Box Co., Ltd | Seoul |
| Cubixel | |
| Curachem | |
| Curacle | Seoul |
| Curamys | Seoul |
| Curocell, Inc. | |
| CUROGEN Technology | |
| Cyber Hankuk University of Foreign Studies | |
| Cyber University of Korea | |
| Cybertek Co., Ltd | Seoul |
| CYMECHS | Gyeonggi |
| CytoGen, Inc. | Seoul |
| Cyworld Z Co. | Seoul |
| D major | Gyeonggi |
| D.CAMP | Seoul |
| d.LEMON Co., Ltd | Seoul |
| Dable | |
| Dae Seung Ind. Co., Ltd | Gwangju |
| Daedong University | |
| Daeduck Electronics Co., Ltd | Gyeonggi |
| Daeduk University | |
| Daegu Arts university | |
| Daegu Catholic University | |
| Daegu Gyeongbuk Institute of Science & Technology | Daegu |