| 2025 International Challenger Zhangjiagang | |
|---|---|
| Date | 25 August – 1 September |
| Edition | 6th |
| Surface | Hard |
| Location | Zhangjiagang, China |
| Champions | |
| Singles | |
 Sho Shimabukuro | |
| Doubles | |
 Luca Castelnuovo /  Akira Santillan | |
The 2025 International Challenger Zhangjiagang was a professional tennis tournament played on hard courts. It was the sixth edition of the tournament which was part of the 2025 ATP Challenger Tour. It took place in Zhangjiagang, China between 25 August and 1 September 2025.
| Country | Player | Rank1 | Seed |
|---|---|---|---|
| AUS | Bernard Tomic | 169 | 1 |
| JPN | Rio Noguchi | 196 | 2 |
| JPN | Sho Shimabukuro | 201 | 3 |
 CHN | Sun Fajing | 215 | 4 |
| JPN | Yasutaka Uchiyama | 227 | 5 |
 GBR | Oliver Crawford | 232 | 6 |
| Ilia Simakin | 238 | 7 | |
 FRA | Arthur Géa | 257 | 8 |
The following players received wildcards into the singles main draw:
The following player received entry into the singles main draw using a protected ranking:
The following players received entry into the singles main draw as alternates:
Luca Castelnuovo 
Sergey Fomin Renta TokudaThe following players received entry from the qualifying draw:
Joshua Charlton 
Huang Tsung-hao Yuta Kikuchi
Filip Peliwo Kaichi Uchida Kaito Uesugi The following player received entry as a lucky loser:
Sho Shimabukuro def. Oliver Crawford 6–3, 3–6, 7–5. Luca Castelnuovo / Akira Santillan def. 
Petr Bar Biryukov / 
Alexandr Binda 6–3, 6–7(8–10), [10–3].