| Dataking Co., Ltd | Seoul |
| Datasolution, Inc. | Seoul |
| Dawonsys Co., Ltd | Gyeonggi |
| Day2Life | Gyeonggi |
| DB HiTek | Gyeonggi |
| DCS Co., Ltd | Seoul |
| DDNS | Seoul |
| Deargen | |
| Deeply, Inc. | |
| DeepScan | Gyeonggi |
| Design Studio R.A.S. | Seoul |
| Desilo, Inc. | |
| Devs United Games | Seoul |
| Devsisters Corporation | Seoul |
| DevStack | Daejeon |
| Devtools | Gyeonggi |
| DFtech Co., Ltd | North Chungcheong |
| Diea Design | Seoul |
| Digent | Seoul |
| Digiatom Co., Ltd | Seoul |
| Diquest | Seoul |
| Direct Hosting | Seoul |
| DNA Link, Inc. | Seoul |
| DNSOFT Co., Ltd | Seoul |
| dob Studio | Seoul |
| domain21.org, Inc. | Seoul |
| Domainbank | Seoul |
| Domainca | Seoul |
| Dong Seoul University | |
| Dong-A ST | Seoul |
| Dong-A ST | |
| Dongkoo Bio & Pharma | |
| Dongwon Parts | Gyeonggi |
| Dongwoon Anatech | Seoul |
| Dongyang Mirae University | Seoul |
| Doomoolmori Co., Ltd | Seoul |
| Doople Incorporation | Gyeonggi |
| Doosan Corporation Electro-Materials | Seoul |
| Doregi | Seoul |
| Dot Incorporation | Seoul |
| Dotname Korea Corporation | Seoul |
| DoubleMe | Seoul |
| DoubleU Games Co., Ltd | Seoul |
| Dowooinsys | North Chungcheong |
| Dragonfly GF Co., Ltd | Seoul |
| DREAMPLUS | |
| DrimSys, Inc. | Seoul |
| DSC Investment | Seoul |
| DSLAB Global | Seoul |
| DSTechno Co., Ltd | Gyeonggi |