Lyot Crater is one of the youngest impact basins > 200 km in diameter on Mars. Although published hydrological models suggest that impact-related groundwater release might have occurred at Lyot, no geomorphic evidence for such activity has been previously identified. Here, we use images acquired predominantly by the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and Mars Odyssey Thermal Emission Imaging Spectrometer (THEMIS) visible and infrared subsystems to document an extensive channeled scabland extending to the north, west, and east of Lyot, covering an area of ∼300,000 km2. The configuration and morphology suggests that the channel-forming fluid was water derived from the target substrate and/or the surrounding terrain. Possible formation mechanisms are groundwater mobilization by seismic energy from the impact event and dewatering of the ejecta blanket.