Abstract Extreme humid‐heat events pose a major hazard across the Yangtze River Basin (YRB), yet their underlying mechanisms and seasonal predictability remain insufficiently understood. Here, using observational diagnostics and coupled model experiments, we identify three independent drivers in the tropical Indo‐Pacific and subtropical North Atlantic during spring‐to‐early summer that significantly influence midsummer humid‐heat days. These drivers jointly induce a quasi‐barotropic anticyclonic anomaly over East Asia, enhancing the advection of warm‐moist air into the YRB. A seasonal prediction model constructed from these drivers demonstrates robust skill, achieving a temporal correlation coefficient of 0.92 (p < 0.01) during independent prediction period 2011–2024 and effectively capturing moderate‐to‐high humid‐heat days anomalies. By introducing a physically constrained framework, this study advances the seasonal prediction of humid‐heat extremes in the YRB.