<p>Exploring the sources of decadal predictability of East Asian winter monsoon (EAWM) and enhancing decadal prediction skill can provide a crucial scientific foundation for the medium-to-long-term national infrastructure planning and disaster risk mitigation strategies. However, to what extent the decadal EAWM can be predicted, the sources of its predictability and underlying physical mechanisms remain unclear. Based on observations and numerical experiments, the present study reveals that the decadal variability of EAWM is primarily modulated by three sea surface temperature anomalies (SSTA) factors: (1) North Atlantic SSTA (NAT): anomalous NAT warming triggers downstream Rossby wave trains that amplify the Siberian High and the Japan Sea Low anomalies, enhancing the zonal pressure gradient to modulate EAWM; (2) North Pacific SSTA (NPT): anomalous NPT cooling enhances low-pressure anomalies from the northwestern Pacific to the Aleutians, driving northerly flow along its western flank to strengthen EAWM; (3) Tropical Central-Eastern Pacific SSTA (TPT): anomalous TPT cooling enhances the Walker Circulation, intensifying the low-pressure anomalies over the Maritime Continent and the meridional pressure gradient towards East Asia, which strengthens northerly wind anomalies over East Asia and reinforces EAWM. Assuming “perfect” predict (i.e., observed value) these three factors, the physics-based empirical model yields a significant temporal correlation coefficient skill of 0.65 for EAWM at a 7–10&#xa0;years lead time during 1971–2017, providing an estimation of the lower bound for potential decadal predictability of EAWM.</p>