2018 Seoul Open Challenger – Singles

Thomas Fabbiano was the defending champion but chose not to defend his title.

Mackenzie McDonald won the title after defeating Jordan Thompson 1–6, 6–4, 6–1 in the final.

Seeds
• # 🇨🇦 Vasek Pospisil (second round)

• # 🇮🇱 Dudi Sela (first round)

• # 🇦🇺 Jordan Thompson (final)

• # Lu Yen-hsun (second round, retired)

• # 🇺🇸 Mackenzie McDonald (champion)

• # 🇯🇵 Go Soeda (second round)

• # Jason Jung (second round)

• # 🇯🇵 Tatsuma Ito (semifinals)