Khat, a commercially cultivated shrub tree, has seen extensive growth throughout Ethiopia. Previous studies have primarily focused on its impact on human health and socio-economic aspects, neglecting the effect of khat plantations on hydrologic response and soil loss. In this study, we investigated the impacts of khat plantations on runoff, soil loss, and soil moisture in the Aba Gerima basin. Four runoff plots were established to monitor these factors during different growth stages of khat. Results showed that as the khat plants matured, both runoff and soil loss significantly decreased. Khat cultivation reduced runoff by 61–67% and soil loss by 54–82% from the initial to maturity stages. Additionally, soil moisture availability increased with the age of the khat plantation. These findings highlight the strong influence of khat cultivation on the hydrological dynamics of the study area, providing valuable insights for policymakers in managing soil and water resources in widespread khat plantations.