The recent climate change accelerations intensify future water availability concerns from high-altitude mountainous regions. The Upper Indus Basin (UIB) is a highly snow-fed and glacierized basin from the High Mountains of Asia; thus, an accelerated melt due to climate change may severely affect these frozen water resources. Therefore, increasing knowledge of the future water availability in the Indus Basin under climate scenarios is vital. This research was designed to analyse the future water availability from the Hunza River Basin (sub-basins of the UIB) under the Coupled Model Intercomparison Project Phase 6 (CMIP6) climatic projections. The projected precipitation and temperature from two General Circulation Models (GCMs) were analysed. The Distance Distribution Dynamics (DDD), a data parsimonious rainfall-runoff model was set up using these projections. The simulations were performed for the historical (1991–2010), middle of the century (2041–2060) and end of the century (2081–2100) period under Shared Socioeconomics Pathways (SSP) SSP1, SSP2 and SSP5 emission scenarios. Relative to the baseline temperature, the future projections showed an increase between 1.1 and 8.6 °C based on both GCMs. The 12–32% annual precipitation increase is expected by the end of the twenty-first century, relative to the baseline precipitation. Furthermore, reduced precipitation as snow and increased rainfall are expected together with the changes in precipitation cycles. Relative to the baseline glacier melt, a 38–265% glacier melt increase is expected in the river flow. An overall river flow increase of 23–126% is expected by the end of the twenty-first century. This research presented climate change associated future water availability for the study area. Thus, policymakers and stakeholders could use these findings for reservoir development, modifying hydropower and reservoir development policy, sustainable agriculture, and efficient water resources management.