Analyses of seismic-reflection profiles collected off New Jersey reveal a large buried channel that splits from the topographic Hudson shelf valley beneath the inner shelf and extends southward for at least 80 km. The buried valley has a flat bottom, a width of 2 to 17 km, and a relief of 3 to 15 m, all features similar to those of the Hudson shelf valley. The buried valley apparently is an ancestral pathway of the Hudson River that has been filled with heterogeneous fluvial deposits and capped by an additional 10 to 30 m of sediments. Vibracores from over or near the ancestral valley show that interbedded marine sand and mud layers constitute the upper part of the sedimentary fill. Radiocarbon ages, geotechnical properties, and micro-paleontological analyses of the core sediments indicate that the valley was formed and filled sometime prior to 28,000 yr ago and then was exposed subaerially during at least one sea-level regression. These results are the first clear subbottom evidence that the ancestral Hudson River flowed south of the Hudson shelf valley on the exposed continental shelf during Pleistocene time.