Assessing available water and suitability of land for surface irrigation is important to understand the irrigation potential and develop implementation plan. The objective of the research is to assess the availability of water resources and land suitability for surface irrigation of Ferfer Woreda in Wabishebele River sub-basin. Geographic Information System (GIS), based on multi-criteria decision analysis (MCDA) were applied for analysis. Factors including LULC, slope, soil type, soil texture class, depth, drainage, cation exchange capacity of the soil, hydraulic conductivity, available water storage, organic carbon content, soil pH, and distance to water sources were considered in the preparation of the irrigation suitability map. From the weighted overlay analysis result, in Ferfer woreda 252,709.52ha (17.17%) of lands are highly suitable and 762,074.94 ha (51.78 %) moderately suitable and 436,564.42 ha (29.66 %), marginally suitable for surface irrigation. from the water resources potential assessment, the flow of Wabishebele River during the dry season (July to August) was relatively low, with average monthly flows ranging from zero to 0.76 m³/s across different sub-watersheds. During the wet season (April to Jun), the river flow increases significantly, reaching peaks of up to 210.46m³/s. Whereas, in the transition months, the river flow decreases but remains moderate, ranging from 0.17 to 61.95 m³/s based on the analysis, the Wabishebele River watershed shows strong potential for surface irrigation during the wet and transition seasons, while the dry season poses challenges that necessitate additional irrigation strategies. Overall, these findings provide valuable insights for irrigation planning, supporting policymakers and stakeholders to make informed decisions regarding to surface irrigation development and the allocation of water resources in the basin. Keywords ArcGIS; Multi-Criteria Decision Analysis; Surface Irrigation Development; Weighted Overlay Analysis; Suitability Map.