| 2018 Seoul Open Challenger | |
|---|---|
| Date | 30 April – 6 May |
| Edition | 4th |
| Surface | Hard |
| Location | Seoul, South Korea |
| Champions | |
| Singles | |
 Mackenzie McDonald | |
| Doubles | |
 Toshihide Matsui / Frederik Nielsen | |
The2018Seoul Open Challenger was a professionaltennis tournament played on outdoorhard courts. It was the fourth edition of the tournament. It was part of the2018 ATP Challenger Tour. It took place inSeoul, South Korea, between 30 April and 6 May 2018.
| Country | Player | Rank1 | Seed |
|---|---|---|---|
 CAN | Vasek Pospisil | 82 | 1 |
 ISR | Dudi Sela | 96 | 2 |
 AUS | Jordan Thompson | 98 | 3 |
 TPE | Lu Yen-hsun | 112 | 4 |
| USA | Mackenzie McDonald | 141 | 5 |
| JPN | Go Soeda | 145 | 6 |
| TPE | Jason Jung | 154 | 7 |
| JPN | Tatsuma Ito | 176 | 8 |
The following players received wildcards into the singles main draw:
Chung Yun-seongHong Seong-chan Kim Young-seokPark Ui-sungThe following player received entry into the singles main draw as a special exempt:
The following players received entry from the qualifying draw:
Makoto Ochi Son Ji-hoon Renta TokudaYosuke WatanukiMackenzie McDonald def.Jordan Thompson 1–6, 6–4, 6–1.Toshihide Matsui /Frederik Nielsen def.Chen Ti /Yi Chu-huan 6–4, 7–6(7–3).