Abstract Interannual variability of the Beaufort Sea (BFS) ice notably affects the oceanic circulation, pelagic and sympagic ecosystems, and navigation activities. However, key physical pathways regulating interseasonal connections between the El Niño‐Southern Oscillation (ENSO) and BFS ice concentration anomalies in early‐summer (May–July) remain unclear. Here, we established that winter (December‐January‐February) ENSO events, identified by the Niño 3 index, explained approximately 25% of BFS ice interannual variability in summer. We demonstrated that ENSO‐induced North Pacific sea surface temperature (NPSST) anomalies persist into summer, triggering poleward‐propagating Rossby waves by strengthening transient eddy vorticity forcing. The resulting anticyclonic and associated easterly anomalies over the BFS drive westward ice drift and subsequent ice reduction. ENSO‐pacemaker simulations confirmed the causal relationship, estimating that NPSSTs contribute 61% to the ENSO‐induced BFS ice anomalies in early summer. Our results emphasize the crucial role of NPSSTs for the ENSO‐Arctic teleconnection, with important implications for seasonal sea‐ice predictability.