In this study, we performed the hazard assessment, vulnerability assessment, and risk analysis of debris flows using a digital elevation model (DEM) obtained from a light detection and ranging (LiDAR) sensor, a numerical analysis model, and a geographic information system (GIS) spatial analysis technique to evaluate the debris flow disaster risk in Bukhansan National Park, which is located in an urban area of Seoul. The debris flow disaster risk analysis involved analyzing the debris flow disaster hazard zones and the exposure and vulnerability to risk elements for different rainfall frequency scenarios, and we determined the risks for two watersheds. We identified the potential risk elements at the watersheds and estimated the total amount of risk to buildings that could occur annually from debris flow disasters. Risk maps were drawn by determining the targets exposed to debris flow hazards at each watershed and by measuring the degree of vulnerability and loss at the watersheds. The findings of this study suggest that it is possible to provide important information to support efficient decision-making processes, such as establishing a hazard zone management plan and preparing structural and non-structural measures to minimize the damage through disaster risk management.