The ductility and toughness of the high-strength wear-resistant steels can be improved by introducing retained austenite. However, the influence of retained austenite on the impact-abrasion wear resistance remains uncertain. This study investigates the effect of retained austenite on the impact wear performance of martensitic wear-resistant steel by introducing 5.2–9.2 vol.% retained austenite through the dynamic partitioning (DP) process. The results display that the microstructures of the various DP-treated steels primarily consist of lath martensite and film-like retained austenite distributed between martensite laths. The three-dimensional atom probe (3DAP) analysis demonstrates that the retained austenite exhibits a significantly higher carbon concentration than the martensite, with carbon enrichment increasing gradually from the edge to the core of the retained austenite. In short-term impact wear tests (10 min), the weight loss of DP-treated steels is inversely proportional to the volume fraction of retained austenite. Conversely, in the long-term impact wear tests (20–90 min), it is positively proportional to the volume fraction of retained austenite. Initially, the strain-induced martensite transformed from retained austenite can absorb more impact energy, passivate the crack, and inhibit crack propagation, which is the dominant factor contributing to improved wear resistance. However, as impact wear progresses, the detrimental effects arising from the high hardness and poor plastic deformation ability of the strain-induced martensite become dominant, accelerating crack propagation during long-term impact wear tests. This study may provide insights into the microstructure design of the martensitic wear-resistant steels under impact wear conditions, specifically regarding the role of retained austenite.