The Southern Ocean exhibits widespread rapid warming in the mid-latitudes, leading to far-reaching consequences for climate and marine ecosystems. While the meridional structure of Southern Ocean warming is well understood, its zonal structure has not been thoroughly investigated yet. This study examines the mechanisms driving inter-basin warming contrasts in the mid-latitudes (35°-55°S) of the Southern Ocean. Using three observational ocean datasets, atmospheric reanalysis data, and historical simulations from Community Earth System Model version 1 large ensemble (CESM1-LE), we analyze the relative roles of surface wind stress and net surface heat flux in shaping the inter-basin warming contrast. Observations reveal that the Atlantic-Indian sector warms significantly faster than the Pacific sector, a pattern largely reproduced by CESM1-LE albeit with a southward shift. Our analysis indicates that intensified wind-driven Ekman transport convergence primarily drive the faster warming in the Atlantic-Indian sector. This is corroborated by ocean model experiments, which show that while net surface heat flux provides the heat source for mid-latitude warming, surface wind stress drives the zonal structure of inter-basin warming contrast. This work fills the gap in understanding zonal structure of the Southern Ocean warming and provides insight into the continuous inter-basin warming contrast projected in the future.