| Seongnam-si Guadalupe | Central Time | 15:00 |
| Seongnam-si Bağcılar | Turkey Time | 06:00 |
| Seongnam-si Sulaymaniyah | Arabian Time | 06:00 |
| Seongnam-si Cúcuta | Colombia Time | 14:00 |
| Seongnam-si Moradabad | India Standard Time | 03:30 |
| Seongnam-si N'Djamena | West Africa Time | 08:00 |
| Seongnam-si Langfang | China Time | 01:00 |
| Seongnam-si Zhumadian | China Time | 01:00 |
| Seongnam-si Yantai | China Time | 01:00 |
| Seongnam-si Lviv | Eastern European Time | 07:00 |
| Seongnam-si Merida | Central Time | 15:00 |
| Seongnam-si Tlalnepantla | Central Time | 15:00 |
| Seongnam-si Edmonton | Mountain Time | 16:00 |
| Seongnam-si Jeonju-si | Korean Time | 00:00 |
| Seongnam-si Zhuzhou | China Time | 01:00 |
| Seongnam-si Subang Jaya | Malaysia Time | 01:00 |
| Seongnam-si Bhiwandi | India Standard Time | 03:30 |
| Seongnam-si Pekanbaru | Western Indonesia Time | 02:00 |
| Seongnam-si Seville | Central European Time | 08:00 |
| Seongnam-si Tolyatti | Samara Time | 05:00 |
| Seongnam-si Jaboatão | Brasilia Time | 12:00 |
| Seongnam-si Shizuoka | Japan Time | 00:00 |
| Seongnam-si Santo Domingo Oeste | Atlantic Time | 13:00 |
| Seongnam-si Rajshahi | Bangladesh Time | 03:00 |
| Seongnam-si City of Balikpapan | Central Indonesia Time | 01:00 |
| Seongnam-si Changzhi | China Time | 01:00 |
| Seongnam-si Bulawayo | Central Africa Time | 07:00 |
| Seongnam-si Zagreb | Central European Time | 08:00 |
| Seongnam-si Agadir | Western European Time | 08:00 |
| Seongnam-si Sarajevo | Central European Time | 08:00 |
| Seongnam-si La Plata | Argentina Time | 12:00 |
| Seongnam-si Tunis | Central European Time | 08:00 |
| Seongnam-si Zhangjiakou | China Time | 01:00 |
| Seongnam-si Zigong | China Time | 01:00 |
| Seongnam-si Fuxin | China Time | 01:00 |
| Seongnam-si Enugu | West Africa Time | 08:00 |
| Seongnam-si Tangier | Western European Time | 08:00 |
| Seongnam-si Huangshi | China Time | 01:00 |
| Seongnam-si Liaoyang | China Time | 01:00 |
| Seongnam-si Sheffield | United Kingdom Time | 09:00 |
| Seongnam-si Seattle | Pacific Time | 17:00 |
| Seongnam-si Denver | Mountain Time | 16:00 |
| Seongnam-si El Paso | Mountain Time | 16:00 |
| Seongnam-si Kumamoto | Japan Time | 00:00 |
| Seongnam-si Raipur | India Standard Time | 03:30 |
| Seongnam-si General Santos | Philippine Time | 01:00 |
| Seongnam-si Dushanbe | Tajikistan Time | 04:00 |
| Seongnam-si Osasco | Brasilia Time | 12:00 |
| Seongnam-si San Luis Potosi | Central Time | 15:00 |
| Seongnam-si Detroit | Eastern Time | 14:00 |