- Fire may alter land cover throughout the landscape and affect run‐off responses to rainfall events in a burnt watershed. Therefore, the challenge is to understand the interactions between forest composition and fire patterns in a karstic, Mediterranean watershed that affects the run‐off regime. The aim of this research is to improve the understanding of the interactive effects of wildfire and land‐cover change on the rainfall–run‐off relationship in a first‐order watershed. To achieve this goal, satellite imagery, official spatial data, and hydrological modelling were used to study forest composition in relation to extreme fire and to simulate run‐off response for 2 rainfall events. The results show that an extreme wildfire had a greater impact on planted forest, composed mostly of pines, than on native species. Additionally, it was found that the land‐cover alternation due to fire affected the run‐off regime and contributed to an increase in maximum discharge and run‐off volume for the 2 rainfall events by ~39–47%. During the regeneration period, the run‐off response for the 2 rainfall events decreased by ~7.7–9%. Wildfires may impact the run‐off response more profoundly as the plantation of pine trees increases. A greater increase in run‐off response may endanger infrastructure in terms of flooding and affect the population well‐being. Watershed management in areas where afforestation is considered should focus on planting native species that are less flammable rather than introducing combustible pines, thus reducing the hydrologic impacts of land‐cover alteration due to wildfire, especially when climate warms and wildfires become more frequent and intense.