Assessment of irrigation potential is essential for the development of irrigation schemes for addressing food security problems. This study focused on assessing surface irrigation potential of Mille watershed in Awash basin Ethiopia. This was done by using GIS-based Analytical Hierarchy Process (AHP-GIS) techniques, a Hydrological Soil and Water Assessment Tools (SWAT) model and a FAO CROPWAT 8.0 model. AHP-GIS was used to identify suitable land for surface irrigation, the SWAT model was used for stream flow simulation and CROPWAT model was used to estimate crop irrigation water requirement for selected dominant crops within the watershed. The gross irrigation requirement was calculated for three seletcted crops (wheat, sorghum and maize) and compared with the available flow to get irrigation potential for surface irrigation. The overlay results of various factors using the AHP-GIS technique under a 85% threshold level gave 91,800 ha of the watershed as a suitable area for surface irrigation. The results of model performance indicators for calibration and validation were in the acceptable range (R2=0.88, NSE=0.87 & PBIAS 0.5) and (R2=0.85, NSE=0.83 & PBIAS=-0.7) respectively. The annual average simulated stream flow was estimated as 17.3 m3/s and the water demand required by the whole selected crops was 57.2 m3/s. Finally, the total suitable irrigation potential of the study watershed was 25,783 ha, which can be irrigated with the available flow of 17.2 m3/s. In general, this study indicated that the surface irrigation potential of the Mille River watershed was limited by the simulated stream flow of the watershed in that the water demand of the crops was much greater than the simulated minimum flow of the rivers in major sub-watersheds. Therefore, to increase the irrigation potential of the River sub-watershed other irrigation methods can be used and construct a water harvesting structure. Keywords: Land suitability, Analytical Hierarchy Process, Mille watershed, SWAT model, CROPWAT Model, Calibration,Validation.