Stadium: Court 7 Round: 26
| ITF Malaysia F2 | 2018/07/10 03:50 | Purcell, Rhett v Oh, Seong-Gook | 7-6,7-5 |
| ITF Malaysia F1 | 2018/07/04 03:30 | Moritani, Soichiro v Oh, Seong-Gook | 6-4,6-0 |
| ITF Malaysia F1 | 2018/07/03 10:05 | Oh, Seong-Gook v Noh, Sang-Woo | 7-6,6-2 |
| ITF Korea F3 | 2018/06/18 03:30 | Oh, Seong-Gook v Hong, Seong Chan | 6-7,0-6 |
| ITF Korea F2 | 2018/06/13 03:05 | Oh, Seong-Gook v Wang, Chukang | 6-1,5-7,7-5 |
| ITF Korea F1 | 2018/06/05 01:00 | Oh, Seong-Gook v Choi, Jae-Won | 1-6,5-7 |
| Challenger Busan Qual | 2018/05/12 02:15 | Jeamoon Lee v Oh, Seong-Gook | 7-6,6-3 |
| Challenger Seoul Qual | 2018/04/28 02:50 | Son, Ji Hoon v Oh, Seong-Gook | 6-3,6-3 |
| ITF Korea F4 | 2018/08/14 02:30 | Kwon, OH-Hee v Im, Seong Taek | 6-3,6-4 |
| ITF Korea F3 | 2018/06/22 03:00 | Yunseong Chung v Kwon, OH-Hee | 6-4,6-1 |
| ITF Korea F3 | 2018/06/20 02:30 | Kwon, OH-Hee v Hong, Seong Chan | 7-5,6-4 |
| ITF Korea F3 | 2018/06/19 06:35 | Cing-Yang Meng v Kwon, OH-Hee | 1-6,2-6 |
| Korea F3, Singles Qualifying | 2018/06/18 06:30 | Kim, Hyeong Don v Kwon, OH-Hee | 2-6,2-6 |
| Korea F3, Singles Qualifying | 2018/06/17 04:30 | Han, Seong Jae v Kwon, OH-Hee | 4-6,1-6 |
| Korea F3, Singles Qualifying | 2018/06/16 03:30 | Jung, Ki-Su v Kwon, OH-Hee | 0-6,1-6 |
| ITF Korea F1 | 2018/06/04 02:20 | Kwon, OH-Hee v Adamson, Alec | 5-7,4-6 |