Groundwater has the greatest potential to provide sustainable water security and socio-economic benefits, especially in the arid and semi-arid regions. The Somali Regional State (SRS) located eastern and southeastern part of Ethiopia majorly has arid and semi-arid climates. The selection of groundwater well site and sustainable mobilization of appropriate resources is a challenge for drinking water supply in the region. The objective of this research is to identify the groundwater potential areas of the Somali region using GIS-based multi-criteria decision analysis techniques. Groundwater distribution spatially conducted in this study using nine major thematic layers are lithology, geomorphology, liniments, slope, soil, rainfall, drainage density, land use/land cover and elevation. Using the Analytical Hierarchy Process (AHP) method, the classes in each layer were ranked and weighted for all thematic layers. Finally, all nine thematic layers were overlaid using the overlay analysis method. Somali regional state groundwater potential map was classified into four classes as: very low, low, moderate and high. The study result showed that about 28,979 Km2 (9%) of the study area has “high” groundwater potential, about 208,503 Km2 (64%) has “moderate” groundwater potential, about 82,595 Km2 (25%) has “low” groundwater potential, and about 6,183 Km2 (2%) has “very low” groundwater potential. It is revealed that northern part of the region, which is around Sitti zone of Shinle, Gabi, Harewa and Beyabahi areas and the central part of upper Fafan, Briqot and Kabridahar areas have high groundwater potential. Validation of groundwater potential map by overlaying collected drilling reports of shallow and deep wells showed a very good agreement of 77.3%. By map removal sensitivity analysis, the groundwater potential map is found more sensitive to geology with a mean variation index of 2.83% and less sensitive to altitude with a mean variation index of -1.22%. Keywords Somali Region. Groundwater Potential. Analytical Hierarchy Process (AHP). Geographical Information System (GIS). Ethiopia