<p>Climate change is leading to several implications regarding water availability and sediment transport. In this sense, assessing the impacts of climate change is essential to ensure the proper management of water resources and impact mitigation at watershed scale. The aim of this study was to analyze the impacts of future climate change on the water balance and sediment transport in the Jaguari River basin, in southeastern Brazil. For this purpose, sixteen General Circulation Models from the Coupled Model Intercomparison Project Phase 6 were evaluated for their accuracy in predicting the historical climate characteristics of the basin, with the best five being used to create a multi-model ensemble under the Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5) scenarios. The SWAT + model was calibrated and validated for streamflow and sediment load in the basin, with performances ranging from satisfactory to very good. The results showed an increase in temperatures and shifts in precipitation patterns in all scenarios. The multi-model ensemble simulations projected reductions in average streamflow at the basin outlet ranging from − 50.85 to − 33.2%, with inter-model variability spanning from − 67.4 to 8.2%. Sediment load simulations exhibited similar behavior, with average reductions between − 32.6 and − 11.3% and a GCM spread ranging from − 55.4 to 4.5%. Despite the uncertainties involved, these results indicate that the region could suffer from serious problems regarding water availability in the future, affecting sectors such as public supply, agriculture and energy generation.</p>