nder global warming, extreme weather events have intensified, profoundly impacting ecosystems and human societies. The Tibetan Plateau (TP), known as the "Asian Water Tower," plays a critical role in regional and global climate systems. This study systematically examines historical changes and future projections of summer extreme precipitation over the TP. Using multi-source observations, we find that both the intensity and frequency of extreme precipitation have consistently increased over past decades and are projected to rise further in the future. Projection uncertainties grow with higher emission scenarios. Applying an emergent constraint approach, we identify regional relationships between global historical warming trends and future TP precipitation changes, with key regions including western North America, western South America, the Sahara, South Africa, Greenland, and southern Asia. Constraining model projections with observations effectively reduces biases and narrows uncertainty ranges. Under SSP585 in the long term (2081–2100), the constrained extreme precipitation increase is reduced from 43–124 mm to 25.2–75.4 mm, cutting inter-model uncertainty by 38.1%. Across all scenarios, uncertainty reductions range from 7.8% to 38.1% for precipitation amount and 0.4% to 42.1% for event frequency. The revised projections indicate a robust future increase in summer extreme precipitation across the TP, particularly under high emissions, with the southern TP showing higher sensitivity to extreme events. These findings provide crucial scientific support for climate adaptation and water resource management.