The sambar deer Rusa unicolor is categorized as Vulnerable on the IUCN Red List because of continuous population decline across its native range. In Taiwan the Formosan sambar deer R. unicolor swinhoii is listed as a protected species under the Wildlife Conservation Act because of human overexploitation. However, its population status remains unclear. We used presence and absence data from line transect and camera-trap surveys to identify key habitat variables and to map potential habitats available to this subspecies in Taiwan. We applied five habitat-suitability models: logistic regression, discriminant analysis, ecological-niche factor analysis, genetic algorithm for rule-set production, and maximum entropy. We then combined the results of all five models into an ensemble-forecasting model to facilitate a more robust prediction. This model indicated the existence of 7,865 km2 of suitable habitat for the sambar deer. Distance from roads and elevation were identified as the most important environmental variables for habitat suitability, and deer preferred areas far from roads and > 1,500 m altitude. The results predicted that suitable deer habitat is mainly located in Taiwan's Central Mountain Range and Xue Mountain Range, with c. 70% of this suitable habitat in protected areas. However, the habitat predicted to be suitable is in five areas separated by mountain highways. We recommend that deer habitats close to the highways should be monitored for the future establishment of corridors between Formosan sambar deer sub-populations.