The assessment of flood risk under climate change impacts is necessary for sustainable flood management strategies at national level. Referring to the aforesaid statement, this research aims to evaluate the potential impacts of climate change on reservoir operations in the Huong River Basin, Vietnam. To enable further representation of climate change impacts, the HadGEM3-RA Regional Climate Model (RCM) under Representative Concentration Pathways (RCPs) 8.5 climate change scenario was used in this study. For assessing the level of flood risk posed to the study area, a coupled HEC-HMS hydrologic model and HEC-RAS hydrodynamic model was used to represent the behaviour of flow regimes under climate change impacts in the Huong River Basin. The key results demonstrated that the mean temperature and mean annual rainfall would be increased in the future from 0.2–0.8°C, and 4.8–6.0%, respectively. Consequently, the mean annual runoff and mean water level would also be increased from 10–30%, and 0.1–0.3 m above mean sea level, respectively. Moreover, the proposed reservoir operation rules corresponding to flood control warning stages was also derived to reduce peak flows downstream during the rainy season. Finally, the main findings of this study can be a good example for future planning of flood control reservoir systems in Vietnam.