Abstract Projection uncertainty fundamentally constrains climate adaptation, yet its evolution in compound heat and precipitation extremes (CHPE) remains poorly understood. Here we quantify CHPE uncertainty using 14 CMIP6 models and two single‐model initial‐condition large ensembles. CHPE shows a delayed transition from model‐dominated to scenario‐dominated uncertainty relative to single heat extremes, owing to persistent precipitation‐side model spread. Regions with the strongest CHPE intensification, including the Amazon, South Asia, and tropical Africa, also emerge as major uncertainty hotspots. In several regions, internal climate variability contributes more strongly to CHPE than to either constituent hazard, indicating enhanced stochasticity in compound‐event occurrence. These results demonstrate that CHPE uncertainty is itself an emerging dimension of climate risk, especially where rapid hazard intensification coincides with persistently limited predictive confidence.