| 2026 Nonthaburi Challenger | |
|---|---|
| Date | 5 – 10 January |
| Edition | 14th |
| Surface | Hard |
| Location | Nonthaburi, Thailand |
| 2025 Champions | |
| Singles | |
 Brandon Holt | |
| Doubles | |
 Ray Ho /  Neil Oberleitner | |
The 2026 Nonthaburi Challenger was a professional tennis tournament played on hard courts. It was the 14th edition of the tournament which was part of the 2026 ATP Challenger Tour. It took place in Nonthaburi, Thailand from 5 to 10 January 2026.
| Country | Player | Rank1 | Seed |
|---|---|---|---|
 CZE | Zdeněk Kolář | 178 | 1 |
 ITA | Lorenzo Giustino | 214 | 2 |
 JPN | Rio Noguchi | 229 | 3 |
 MEX | Rodrigo Pacheco Méndez | 231 | 4 |
| JPN | Kaichi Uchida | 252 | 5 |
| AUT | Joel Schwärzler | 256 | 6 |
| USA | Andres Martin | 271 | 7 |
 CHN | Sun Fajing | 276 | 8 |
The following players received wildcards into the singles main draw:
Kasidit Samrej Pawit Sornlaksup Wishaya Trongcharoenchaikul The following players received entry from the qualifying draw:
Tibo Colson Taisei Ichikawa Koki Matsuda Hayato Matsuoka Hiroki Moriya Hikaru Shiraishi
vs. / vs. /