Antarctic marginal seas play a pivotal role in the global climate system, yet direct observational constraints on their key dynamical features—particularly mesoscale ocean eddies and the Antarctic Slope Current (ASC)—remain critically limited. Here we leverage the unprecedented high-resolution sea surface height measurements from the recently launched Surface Water and Ocean Topography (SWOT) satellite to reveal a widespread distribution of mesoscale eddies across the Antarctic continental shelf, alongside the fine-scale frontal structure of the ASC. The spatial patterns of the observed eddies, supported by eddy-resolving model simulations, are consistent with the hypothesis that ice-shelf basal melting and dense shelf water formation serve as primary drivers of the pervasive eddy activity. Furthermore, we find that the buoyancy distribution over the continental shelf exerts a substantial control on both the strength and the along-slope direction of the ASC. Collectively, these findings demonstrate the transformative potential of next-generation satellite altimetry for monitoring critical ocean processes in the polar regions, and they underscore an urgent need to resolve Antarctic eddies and the ASC in climate-scale models in order to reduce uncertainties in projections of ice-sheet stability and global sea-level rise.