Regional and local hydrological regimes are expressively exposed to global climate change, which is considered to be one of the major problems threating water resources and flood security. This research has been done aimed at the examination of the effect of climate change on the hydrology of Borkena watershed, Awash River Basin during 2030s (2021-2040), 2050s (2040-2060), and 2070s (2061-2080) future periods. To realize this, the distributed hydrological SWAT Model driven by three different Global Circulation Models (MIROC5, MPI, and IPSL) under two Representative Concentration Pathway emission scenarios (RCP4.5 and RCP8.5) was used. As result, the GCM projection indicated that, the mean annual maximum and minimum temperature projected to increases by 0.56°c and 0.31°c respectively while the mean annual rainfall has no a significant change in the coming decades. The study also resulted in a considerable average monthly and seasonal, rainfall change in magnitude and direction. Relative to the baseline period the changes in mean annual stream flow from (2021-2080) are mostly negative and indicate a reduction in volume of discharge available in the Borkena river. In addition, trends in the extreme flow are also determined for high and low flows and the results show a forceful negative trend for extreme stream flows and flood volumes may decrease by 43.1% in RCP4.5 under MPI (2021–2040), 38.6% (2041–2060) and 49.4% (2061–2080) in RCP8.5 under IPSL and MIROC5 respectively. These findings will serve as a nearly warning for the alarming extreme weather events for the future period in Borkena watershed as well as Awash River basin which require sustainable and effective adaptive measures for future water resource management.