The impact of debris flow is not only limited to the source area but it is also significantly governed by the runout. It is evident in many parts of the world, and it is also a usual phenomenon in the Himalayan environment. Even though a significant body of scientific work was concentrated on landslide susceptibility in this region, studies focused on the debris flow runout assessment are still scarce. Therefore, this study aims to develop a debris flow susceptibility assessment in the Kalimpong region (Himalaya, India) by integrating the initiation and runout areas. Additionally, the changes in exposed elements for different susceptibility zones are analysed between 2006 and 2018. The methodological framework considers two different approaches: the modelling of debris flow initiation based on the logistic regression method and the assessment of the runout using the Flow-R model. Regarding the debris flow initiation, the logistic regression model comprises eleven conditioning factors and shows an area under the receiver operating characteristic curve of 0.88. For the runout assessment, 139 models are simulated for selecting Flow-R parameters. The best combination of the Holmgren exponent of 4, the travel angle of 5° and the velocity of 13 m s⁻¹ produced the model with a true positive rate of 86.6% for the whole area. The final debris flow susceptibility model is generated by integrating the initiation and the runout areas. Lastly, a substantial change of buildings (+18%), roads (+27%) and agricultural land (−12%) can be found within the debris flow susceptible areas between 2006 and 2018.