Understanding how severe wildfires influence faunal movement is essential for predicting how changes in fire regimes will affect ecosystems. We examined the effects of fire severity distribution on spatial and temporal variation in movement of an Australian arboreal mammal, the mountain brushtail possum (Trichosurus cunninghami). We used GPS telemetry to characterise the movements of 18 possums in landscapes burnt to differing extents by a large wildfire. We identified a temporal change in movement patterns in response to fire. In unburnt landscapes, individuals moved greater distances early and late in the night and had less overlap in the areas used for foraging and denning, than in high-severity burnt landscapes. Habitat selection was dependent on the spatial context of fire in the surrounding landscape. Forest recently burnt at high severity may provide suitable habitat for species such as the mountain brushtail possum, if protected from subsequent disturbance, such as salvage logging. However, spatial and temporal patterns of habitat use and selection differ considerably between burnt and undisturbed landscapes. The spatial outcomes of ecological disturbances such as wildfires have the potential to alter the behaviour and functional roles of fauna across large areas.