Abstract An unprecedented dust storm struck southern China in April 2025, affecting hundreds of millions of people in regions rarely impacted by dust storms and challenging existing understanding of lower‐latitude dust storms. Here, we show that polar stratospheric signals enabled this event by modulating tropospheric teleconnection, revealing an emerging mechanism of stratosphere‐troposphere dynamical interactions for tropospheric extreme events. Specifically, this event was driven by record‐breaking northerly winds between an anomalously displaced Mongolian High and an intensified Northeast China Cold Vortex. In the troposphere, the Scandinavian pattern dispersed energy from a persistent North Atlantic blocking high, amplifying the European Low and Mongolian High. Descending stratospheric anomalies over Eurasia forced the Mongolian High to migrate southward through wave‐mean flow feedback, redirecting wave energy to efficiently amplify the Northeast China Cold Vortex. Numerical experiments confirm that both tropospheric energy dispersion and stratospheric descending signals were crucial for the event’s predictability.