Abstract The Arctic has warmed at more than twice the global mean rate, with winter anomalies over the Barents‐Kara Seas (BKS) linked to remote tropical forcing. While El Niño Southern Oscillation is often emphasized, the role of the Atlantic Niño remains poorly understood. Using reanalysis data and CESM2 large‐ensemble simulations, we show that summer Atlantic Niño sea surface temperature anomalies persist into autumn and induce cross‐basin atmospheric circulation adjustments that extend their influence to the Arctic. These changes trigger wave activity that propagates into the stratosphere, where the signal is stored and released downward in winter, producing a negative NAO‐like circulation. This response reinforces a dipole in Arctic surface air temperature, with cooling over the BKS and Eurasia and warming over Greenland and northeastern Canada. These results identify the Atlantic Niño as a predictable driver of Arctic variability, with implications for seasonal prediction.