High-resolution autonomous underwater vehicle (AUV)-based multibeam bathymetry and chirp sub-bottom profiles were used to map the axial channels of Santa Monica and Redondo Canyon-Channel Systems, offshore southern California. The new bathymetry reveals the seafloor morphology at 1-meter grid resolution, whereas sub-bottom chirp and regional multichannel seismic reflection (MCS) profiles allow characterizing the shallow and deep sedimentary record, respectively. Even though these two submarine canyons have coexisted under the same regional controls (i.e., tectonics and sea-level changes), they have evolved distinctly over time. Turbidity current activity along the Redondo Canyon-Channel System as a result of canyon-head incision to the present-day shoreline resulted in a different geomorphology compared to the abandoned Santa Monica Canyon.