Floods are natural events in tropical monsoon climates, often causing significant adverse impacts on lives, livelihoods, and infrastructure. To address these challenges, the flood susceptibility map has a significant role in identifying high-risk areas and aiding in effective disaster preparedness, sustainable urban planning, and environmental conservation. Therefore, this chapter attempts to generate a flood susceptibility map for the Kaljani River Basin using the AHP-PROMETHEE II and AHP methods. Fourteen factors were considered in the computation, such as elevation, plan curvature, profile curvature, NDWI, rainfall, slope, flow accumulation, aspect, TWI, TRI, LULC, STI, SPI, and soil texture. The results indicated that elevation (17.66%), plan curvature (13.66%), profile curvature (11.76%), and NDWI (10.41%) were the most dominant factors in making the flood susceptibility map. Conversely, soil texture (1.33%), SPI (1.74%), STI (2.16%), LULC (2.85%), and TRI (3.74%) had a relatively lower influence. The susceptibility maps generated using both the AHP-PROMETHEE II and AHP methods indicated an increasing likelihood of flood susceptibility from the northern to the southern parts of the basin. The accuracy of the developed AHP-PROMETHEE II method was evaluated using several score metrics, including precision (88.89%), recall (87.27%), and F1 (88.13%). On the other hand, the score metrics for the AHP method were precision (75.56%), recall (73.18%), and F1 (74.91%). The chapter’s outcome would be valuable for policymakers connected to water resource management, managers, and decision-makers in formulating effective flood management strategies.