| Doubles | |
|---|---|
| 2018 Fairfield Challenger | |
| Champions |  Sanchai Ratiwatana  Christopher Rungkat |
| Runners-up |  Harri Heliövaara  Henri Laaksonen |
| Final score | 6–0, 7–6(11–9) |
Luke Bambridge and David O'Hare were the defending champions but chose not to defend their title.
Sanchai Ratiwatana and Christopher Rungkat won the title after defeating Harri Heliövaara and Henri Laaksonen 6–0, 7–6(11–9) in the final.
Sanchai Ratiwatana / Christopher Rungkat (Champions)
Ruan Roelofse / 
John-Patrick Smith (Quarterfinals)
Evan King / Nathan Pasha (First round)
Toshihide Matsui / 
Frederik Nielsen (First round)| First Round | Quarterfinals | Semifinals | Final | ||||||||||||||||||||||||
| 1 | Sa Ratiwatana C Rungkat | 6 | 6 | ||||||||||||||||||||||||
| T Kokkinakis M Reid | 3 | 4 | 1 | Sa Ratiwatana C Rungkat | 6 | 5 | [10] | ||||||||||||||||||||
| Q |  A Göransson A Siljeström | 6 | 2 | [6] | WC | H Johnson Y Johnson | 4 | 7 | [6] | ||||||||||||||||||
| WC | H Johnson Y Johnson | 4 | 6 | [10] | 1 | Sa Ratiwatana C Rungkat | 6 | 6 | |||||||||||||||||||
| 3 | E King N Pasha | 3 | 5 | M-A Hüsler  S Verbeek | 4 | 4 | |||||||||||||||||||||
| WC | JC Aragone M Krueger | 6 | 7 | WC | JC Aragone M Krueger | 2 | 4 | ||||||||||||||||||||
| M-A Hüsler S Verbeek | 6 | 6 | M-A Hüsler S Verbeek | 6 | 6 | ||||||||||||||||||||||
 H Hach Verdugo  A Menéndez Maceiras | 4 | 4 | 1 | Sa Ratiwatana C Rungkat | 6 | 711 | |||||||||||||||||||||
| PR | L Harris D O'Brien | 5 | 4 | H Heliövaara H Laaksonen | 0 | 69 | |||||||||||||||||||||
R Galloway  R Maytín | 7 | 6 | R Galloway R Maytín | w/o | |||||||||||||||||||||||
| A Lawson H Reese | 6 | 77 | A Lawson H Reese | ||||||||||||||||||||||||
| 4 | T Matsui F Nielsen | 3 | 63 | R Galloway R Maytín | 5 | 4 | |||||||||||||||||||||
| H Heliövaara H Laaksonen | 77 | 77 | H Heliövaara H Laaksonen | 7 | 6 | ||||||||||||||||||||||
 R Gonzales N Lammons | 62 | 62 | H Heliövaara H Laaksonen | 3 | 6 | [10] | |||||||||||||||||||||
| WC | D Nguyen M Seeberger | 77 | 3 | [5] | 2 | R Roelofse J-P Smith | 6 | 2 | [7] | ||||||||||||||||||
| 2 | R Roelofse J-P Smith | 64 | 6 | [10] | |||||||||||||||||||||||
Gong Maoxin and Li Zhe were the defending champions, but Lee Hsin-han and Christopher Rungkat defeated them in the quarterfinals.
Pierre-Ludovic Duclos and Riccardo Ghedin won the title, defeating Nicholas Monroe and Ludovic Walter 6–4, 6–4 in the final.
Christopher Rungkat and Elbert Sie were the defending champions, but Sie was not selected for the Thai team. Rungkat partnered Sunu Wahyu Trijati, but they lost in the quarterfinals to Francis Alcantara and Treat Huey.
2nd seeds Johan Brunström and Frederik Nielsen won the title, beating Francis Casey Alcantara and Christopher Rungkat 6–2, 6–2
Sanchai Ratiwatana and Sonchat Ratiwatana were the defending champions but only Sonchat Ratiwatana defended his title, partnering Yi Chu-huan. Ratiwatana lost in the semifinals to Daniel Masur and Ante Pavić.
Luke Saville and Jordan Thompson were the defending champions but chose not to defend their title.
Hsieh Cheng-peng and Yang Tsung-hua were the defending champions but lost in the semifinals to Sanchai and Sonchat Ratiwatana.
Stefan Kozlov and John-Patrick Smith were the defending champions but chose not to defend their title.
Denise Dy and Treat Huey were the defending champions having won the event in 2015, but Huey chose not to participate
Daniel Masur and Ante Pavić were the defending champions but chose not to defend their title.
Matt Reid and John-Patrick Smith were the defending champions but chose not to defend their title.
Sanchai and Sonchat Ratiwatana were the defending champions but lost in the quarterfinals to Hsieh Cheng-peng and Yang Tsung-hua.
Sanchai and Sonchat Ratiwatana were the defending champions but lost in the first round to Gong Maoxin and Hsieh Cheng-peng.
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.
Marco Chiudinelli and Teymuraz Gabashvili were the defending champions but chose not to defend their title.
Hsieh Cheng-peng and Peng Hsien-yin were the defending champions but chose to defend their title with different partners. Hsieh partnered Christopher Rungkat and successfully defended his title. Peng partnered Aliaksandr Bury but lost in the semifinals to Hsieh and Rungkat.
Sanchai Ratiwatana and Christopher Rungkat were the defending champions but only Rungkat chose to defend his title, partnering Roberto Maytín. Rungkat lost in the final to Austin Krajicek and Jeevan Nedunchezhiyan.
Sriram Balaji and Vishnu Vardhan were the defending champions but chose not to defend their title.
André Göransson and Florian Lakat were the defending champions but lost in the quarterfinals to Gerard Granollers and Pedro Martínez.
Brydan Klein and Joe Salisbury were the defending champions but chose not to defend their title.
Sanchai Ratiwatana and Christopher Rungkat were the defending champions but chose not to defend their title.