This study aimed to assess land degradation sensitivity of an area contributing to desertification risk in Lam Ta Kong Watershed using the Environmental Sensitivity Area Index (ESAI). Five risk factors comprised climatic, soil, geographical, land utilization and vegetation, and water resources factors together with fifteen sub-factors were used to analyze the sensitivity to land degradation. The spatial analysis was calculated using Geographic Information System (GIS) and Remote Sensing (RS) techniques. The key factors influencing land degradation risks in the watershed area were analyzed using the triangular fuzzy numbers (TFNs) method. The results showed that approximately 33% of the Lam Ta Kong watershed was affected by a high desertification risk excluded the water bodies and around 24.64% of the area suffered from a moderate risk. This research pointed out that key factors causing land degradation and desertification in the watershed area were related to the soil factors, followed by climatic, geographical factors, water resources, and land utilization and vegetation, respectively. The results of this study can be used as a database for planning and implementing area-based mitigations and measures as well as for land use planning in the watershed area.