The 2018 Seoul Open Challenger was a professional tennis tournament played on outdoor hard courts. It was the fourth edition of the tournament. It was part of the 2018 ATP Challenger Tour. It took place in Seoul, South Korea, between 30 April and 6 May 2018.
Singles main draw entrants
Seeds
1 Rankings as of 23 April 2018.
Other entrants
The following players received wildcards into the singles main draw: Chung Yun-seong Hong Seong-chan Kim Young-seok Park Ui-sung
The following player received entry into the singles main draw as a special exempt: Kamil Majchrzak
The following players received entry from the qualifying draw: Makoto Ochi Son Ji-hoon Renta Tokuda Yosuke Watanuki
Champions
Singles
Mackenzie McDonald def. Jordan Thompson 1–6, 6–4, 6–1.
Doubles
Toshihide Matsui / Frederik Nielsen def. Chen Ti / Yi Chu-huan 6–4, 7–6(7–3).