| C & C International Venture Co., Ltd | Bangkok |
| C.E. ANTS Co., Ltd | Bangkok |
| Canon Thailand | Bangkok |
| CANS Communication | |
| Captuscom Design Solutions | Bangkok |
| CAT Telecom Public Co., Ltd | Bangkok |
| CCM Systems Co., Ltd | Bangkok |
| CCT Technology Co., Ltd | |
| CD Organizer | Bangkok |
| CDG Group | Bangkok |
| Cenergy Innovation Ltd | Bangkok |
| Centre for Content Promotion | |
| Chaiyaphum Rajabhat University | |
| Chaiyo Hosting | Bangkok |
| Chaiyo Ready Web | Bangkok |
| Chaopraya University | |
| Charoen Pokphand Group | |
| Chiang Mai Rajabhat University | |
| Chiang Mai University | |
| Chiang Mai University - Department of Mathematics | Chiang Mai |
| Chiang Mai Vocational College | |
| Chiang Rai Rajabhat University | |
| Chiangrai College | |
| Christian University of Thailand | |
| Chulabhorn Graduate Institute | |
| Chulabhorn Research Institute | |
| Chulabhorn Royal Academy | |
| Chulalongkorn University | Bangkok |
| Chulalongkorn University - Department of Computer Engineering | Bangkok |
| Chulalongkorn University - Department of Mathematics | Bangkok |
| CIPHER | |
| Clicksee Network | Bangkok |
| ClickseeDesign | Bangkok |
| Clockwork Media Co., Ltd | Bangkok |
| Cloud HM Co., Ltd | Bangkok |
| CloudCommerce | Bangkok |
| CMKL University | Bangkok |
| Code Gears Co., Ltd | Bangkok |
| Code Gears Co., Ltd | |
| Codebox Co., Ltd | |
| CODEDIVA | |
| College of Asian Scholars | |
| ColorPack Creations Co., Ltd | Bangkok |
| Com7 International Co., Ltd | Bangkok |
| Comp Trading Co., Ltd | Bangkok |
| Compass IT Solutions | |
| Computer Union Co., Ltd | Bangkok |
| Computerlogy Co., Ltd | Bangkok |
| ComSeven | Bangkok |
| Conicle Co., Ltd | |