The 2018 OEC Kaohsiung was a professional tennis tournament played on hard courts. It was the seventh edition of the tournament which was part of the 2018 ATP Challenger Tour. It took place in Kaohsiung, Taiwan between 17 and 23 September 2018.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 France | Gaël Monfils | 42 | 1 | |
 Tunisia | Malek Jaziri | 63 | 2 | |
 Australia | Jason Kubler | 92 | 3 | |
| Jason Jung | 121 | 4 | ||
| Lloyd Harris | 131 | 5 | ||
 India | Ramkumar Ramanathan | 135 | 6 | |
| Ernests Gulbis | 146 | 7 | ||
| India | Prajnesh Gunneswaran | 162 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry into the singles main draw as special exempts:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
See main article: 2018 OEC Kaohsiung – Singles.
Gaël Monfils def. 
Kwon Soon-woo 6–4, 2–6, 6–1.See main article: 2018 OEC Kaohsiung – Doubles.
