Oceanic mesoscale eddies typically span tens to hundreds of kilometers and last several weeks to months. They are a key dynamic process influencing the distribution of oceanic energy, affecting energy budgets, heat distributions, and material transport. Advances in satellite remote sensing and in situ observation over the past half-century have substantially enhanced our understanding of the statistical properties, energetics, and dynamic mechanisms of mesoscale eddies, establishing this field as a major focus in physical oceanography. This article presents a comprehensive review of recent advancements in 6 key areas of mesoscale eddy research: (a) eddy detection methods and data products (leading automated detection methods and the corresponding eddy datasets and data products currently available), (b) eddy generation and dissipation (eddy generation, development, and dissipation mechanisms), (c) energy cascades (energy cascades between eddies, large-scale circulation and submesoscale processes, the role of these processes in modulating the energy transfer of near-inertial internal and surface waves, and research progress in related parameterization), (d) air–sea interaction (eddy-induced interactions, especially the interaction between eddies and typhoons), (e) interdisciplinary studies (impacts of eddies on biogeochemistry, acoustics, and other related fields), and (f) observation studies (programs dedicated to studying mesoscale eddies through in situ observation). This article also discusses research prospects on mesoscale eddies.