Heat is the most frequent cause of extreme weather-related deaths in Australia, and heat-related deaths may increase under a changing climate. This study presents an assessment of the future impacts of climate change on heat-related mortality in Perth through a two-stage time series design using a distributed lag non-linear model. Heat-related deaths are projected to increase by 55.3% in the 2050s under a medium emissions scenario RCP 4.5, with the increase particularly significant among older demographics. This is coupled with a heightened likelihood of years with extreme heat-related mortality. These projections can aid local decision makers engaged in adaptation planning.