The objective of this paper is to the potential application of weighted index overlay analysis for assessing land suitability evaluation for surface irrigation at Bedessa watershed, Ethiopia using geographic information system (GIS) and AHP technique. To identify potential irrigable land, irrigation suitability five factors such as soil, slope, land use / land cover, river proximity and road proximity were taken into account. development. By weighing values of these constraint irrigation factor data sets by using AHP tool in Arc GIS, resulted from these analysis irrigation suitability maps was developed and potential irrigation land for irrigation was as 1.81%, 5.64% 86.83%, and 5.72% for S1, S2, S3, and N respectively. Based on the data from meteorological station, the irrigation water requirement was calculated using FAO-Penman-Monteith methods. By using Crop Wat version 8.0 model, the irrigation requirement of the selected crops was calculated and the result implies that irrigation water requirement was higher at driest months of the year. In conclusion Potential irrigable land was drawn by comparing the gross irrigation demand of identified irrigable land with respect to available monthly river flow. As a result, the map generated using this platform could be used as a preliminary reference in selecting suitable sites for irrigation in the area.