The East Asian winter monsoon (EAWM) is a key component of the East Asian climate system, significantly influencing winter weather patterns. The El Niño-Southern Oscillation (ENSO) is recognized as a major driver of EAWM interannual variability. Although the ENSO-EAWM relationship has been extensively studied, uncertainties remain regarding its seasonal variation between early winter (November-December) and late winter (January-March), as well as the role of modulation by the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO). To address inconsistencies arising from the use of traditional EAWM indices, which are often sensitive to regional definitions, this study employs a circulation-based approach using 850 hPa horizontal wind anomalies over East Asia and the western North Pacific. A 17-year sliding window regression between the Niño 3.4 index and the wind field is conducted for the period 1948—2014, separately for early and late winter. The resulting regression fields are subjected to multivariate empirical orthogonal function (EOF) analysis to identify dominant modes of variability and track the evolving ENSO-EAWM relationship independent of any predefined index.Interdecadal variations in this relationship are examined using NCEP-NCAR reanalysis and NOAA sea surface temperature datasets. A combination of multivariate EOF analysis, sliding correlation, and regression diagnostics is used to investigate the temporal evolution and mechanisms underlying changes in the ENSO-EAWM linkage. Results show that ENSO has a stronger influence on the EAWM in early winter, characterized by more pronounced southerly anomalies into northern East Asia. A notable weakening of the ENSO-EAWM relationship is observed after the early 1980s across both seasonal periods. Further analysis reveals the distinct roles of the PDO and AMO in modulating the ENSO-EAWM connection. During early winter, the formation of the PNA (Pacific-North American teleconnection) suppresses the development of the northwestern Pacific anomalous anticyclone typically associated with El Niño. As the PNA pattern tends to persist into late winter, the PDO exerts a stronger modulation during early winter, particularly during negative PDO phases. In these phases, positive height anomalies in the tropics extend westward into the subtropical western Pacific, intensifying the ENSO impact on the EAWM. Conversely, in late winter under negative PDO conditions, a weakened PNA allows for the resurgence of the anomalous anticyclone, thereby enhancing the ENSO-EAWM linkage. In contrast, the AMO modulates the ENSO-EAWM relationship primarily in late winter, with its influence confined to the tropics. Negative AMO phases enhance the ENSO signal, strengthening the EAWM response relative to positive AMO phases. This asymmetric modulation highlights the seasonally distinct impacts of decadal-scale oceanic variability on interannual ENSO-EAWM interactions.Additional factors influencing this relationship include the Arctic Oscillation (AO), whose negative phase strengthens anticyclonic anomalies over the northwestern Pacific, and sea ice variability in the Barents and Kara Seas. The diversity of ENSO types is also acknowledged as a potential contributor. These findings underscore the complex, seasonally dependent nature of the ENSO-EAWM relationship and emphasize the importance of accounting for both tropical and high-latitude influences when assessing East Asian winter climate variability.