| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| On'gogae | city | Gyeonggi | Korea, Republic of (South) | 37.78 | 127.23 | 830 | 38171 |
| Onam | city | Gyeonggi | Korea, Republic of (South) | 37.70 | 127.21 | 285 | 98136 |
| Onam-ri | city | Gyeonggi | Korea, Republic of (South) | 37.69 | 127.22 | 830 | 90666 |
| Onamni | city | Gyeonggi | Korea, Republic of (South) | 37.69 | 127.22 | 830 | 90666 |
| Onbang | city | Gyeonggi | Korea, Republic of (South) | 37.34 | 127.50 | 167 | 39722 |
| Ondong-mal | city | Gyeonggi | Korea, Republic of (South) | 37.73 | 127.14 | 830 | 204788 |
| Ong-ch'on | city | Gyeonggi | Korea, Republic of (South) | 36.99 | 127.15 | 32 | 69965 |
| Ong-ch’on | city | Gyeonggi | Korea, Republic of (South) | 36.99 | 127.15 | 32 | 69965 |
| Ongcheon | city | Gyeonggi | Korea, Republic of (South) | 36.99 | 127.15 | 32 | 69965 |
| Ongjeong | city | Gyeonggi | Korea, Republic of (South) | 37.04 | 127.02 | 52 | 100594 |
| Ongjŏng | city | Gyeonggi | Korea, Republic of (South) | 37.04 | 127.02 | 52 | 100594 |
| Ongmani | city | Gyeonggi | Korea, Republic of (South) | 37.26 | 127.37 | 830 | 61623 |
| Ongnyeobong | city | Gyeonggi | Korea, Republic of (South) | 37.41 | 127.68 | 308 | 9681 |
| Ongnyobong | city | Gyeonggi | Korea, Republic of (South) | 37.41 | 127.68 | 308 | 9681 |
| Ongp'o | city | Gyeonggi | Korea, Republic of (South) | 37.04 | 126.92 | 29 | 7972 |
| Ongpo | city | Gyeonggi | Korea, Republic of (South) | 37.04 | 126.92 | 29 | 7972 |
| Ongp’o | city | Gyeonggi | Korea, Republic of (South) | 37.04 | 126.92 | 29 | 7972 |
| Onnamu-gol | city | Gyeonggi | Korea, Republic of (South) | 37.09 | 127.33 | 357 | 8740 |
| Onnamu-gol | city | Gyeonggi | Korea, Republic of (South) | 37.46 | 127.47 | 364 | 10065 |
| Onsŏk-ri | city | Gyeonggi | Korea, Republic of (South) | 37.17 | 126.85 | 59 | 7548 |
| Onwi | city | Gyeonggi | Korea, Republic of (South) | 37.98 | 127.45 | 1013 | 924 |