In the 2018 Seoul Open Challenger Doubles tennis tournament, Hsieh Cheng-peng and Peng Hsien-yin were the defending champions but chose to defend their title with different partners. Hsieh partnered Christopher Rungkat but lost in the quarterfinals to Toshihide Matsui and Frederik Nielsen. Peng partnered Aliaksandr Bury but lost in the semifinals to Chen Ti and Yi Chu-huan.
| Doubles | |
|---|---|
| 2018 Seoul Open Challenger | |
| Champions |  Toshihide Matsui Frederik Nielsen |
| Runners-up |  Chen Ti Yi Chu-huan |
| Score | 6–4, 7–6(7–3) |
Matsui and Nielsen won the title after defeating Chen and Yi 6–4, 7–6(7–3) in the final.
Seeds edit
Hsieh Cheng-peng / 
Christopher Rungkat (quarterfinals)
Sanchai Ratiwatana / Sonchat Ratiwatana (first round)
Aliaksandr Bury / Peng Hsien-yin (semifinals)
Matt Reid / 
Dudi Sela (quarterfinals)
Draw edit
Key edit
- Q = Qualifier
- WC = Wild card
- LL = Lucky loser
- Alt = Alternate
- SE = Special exempt
- PR = Protected ranking
- ITF = ITF entry
- JE = Junior exempt
- w/o = Walkover
- r = Retired
- d = Defaulted
- SR = Special ranking
| First round | Quarterfinals | Semifinals | Final | ||||||||||||||||||||||||
| 1 | C-p Hsieh C Rungkat
| 6 | 3 | [10] | |||||||||||||||||||||||
| WC |  Kim Yu-seob Lim Hyung-chan
| 4 | 6 | [2] | 1 | C-p Hsieh C Rungkat
| 62 | 1 | |||||||||||||||||||
| T Matsui F Nielsen
| 6 | 6 | T Matsui F Nielsen
| 77 | 6 | ||||||||||||||||||||||
| WC | Kim Young-seok D-h Lee
| 4 | 2 | T Matsui F Nielsen
| 6 | 3 | [15] | ||||||||||||||||||||
| 4 |  M Reid D Sela
| 1 | 6 | [10] | T Ito M McDonald
| 4 | 6 | [13] | |||||||||||||||||||
| LL | M Banes B Ellis
| 6 | 3 | [8] | 4 | M Reid D Sela
| 4 | 5 | |||||||||||||||||||
| T Ito M McDonald
| 4 | 6 | [10] | T Ito M McDonald
| 6 | 7 | |||||||||||||||||||||
| WC | Lim Min-seob Yoon Il-sang
| 6 | 3 | [2] | T Matsui F Nielsen
| 6 | 77 | ||||||||||||||||||||
 R Gonzales J Jung
| 4 | 6 | [12] | T Chen C-h Yi
| 4 | 63 | |||||||||||||||||||||
| Q | Y-s Chung Yo Watanuki
| 6 | 2 | [10] | R Gonzales J Jung
| 4 | 6 | [6] | |||||||||||||||||||
 K Majchrzak L Saville
| 2 | 4 | 3 |  A Bury H-y Peng
| 6 | 1 | [10] | ||||||||||||||||||||
| 3 | A Bury H-y Peng
| 6 | 6 | 3 | A Bury H-y Peng
| 4 | 64 | ||||||||||||||||||||
 D Wu Ze Zhang
| 6 | 6 | T Chen C-h Yi
| 6 | 77 | ||||||||||||||||||||||
| M Gong Y Uchiyama
| 2 | 3 | D Wu Ze Zhang
| 5 | 2 | ||||||||||||||||||||||
| T Chen C-h Yi
| 78 | 4 | [10] | T Chen C-h Yi
| 7 | 6 | |||||||||||||||||||||
| 2 |  Sa Ratiwatana So Ratiwatana
| 66 | 6 | [8] | |||||||||||||||||||||||