Climate change exacerbates global wildfire risk, particularly in the wildland–urban interface (WUI), which constitutes a zone of heightened wildfire susceptibility. Understanding the spatiotemporal evolution patterns and fire vulnerability characteristics of the WUI is therefore crucial for regional ecological security and sustainable development. This study focuses on the impacts of wildfires on WUI ecosystems and human health. To assess these impacts, we developed a comprehensive fire vulnerability index. This index provides a framework for systematically evaluating the spatiotemporal evolution of China’s WUI and its associated fire vulnerability patterns under various climate change scenarios. Climate change will significantly influence the future spatiotemporal evolution of China’s WUI. Under the SSP1-2.6 and SSP2-4.5 scenarios, the national WUI area exhibited a significant decreasing trend, with rates of 8030 km² per decade (p < 0.01) and 7060 km² per decade (p < 0.01), respectively. By the end of the 21st century, China’s WUI is projected to shift eastward. Concurrently, the boundaries between forests and urban areas are expected to become increasingly diffuse, and anthropogenic influences on surrounding forest areas will intensify. The WUI fire vulnerability is highest in southern China, particularly in Southwest (0.27–0.31), whereas northern China presents relatively lower values. Under the high-emission scenario SSP5-8.5, the national WUI fire vulnerability showed a significant increasing trend (0.00016 per year, p < 0.01), with particularly pronounced increases in Southwest and Northwest China. Both the spatial distribution of WUI areas and their fire vulnerability exhibit significant regional variations and scenario dependence under climate change. High-emission scenarios increase China’s WUI fire vulnerability, thereby exacerbating the risk of fire-related losses across regions. This study elucidates the complex impacts of climate change on China’s WUI and its fire vulnerability, providing a crucial reference for developing targeted fire prevention strategies across different regions.