Byrd Subglacial Basin () is a major subglacial basin of West Antarctica, extending east-west between the Crary Mountains and the Ellsworth Mountains. It is bounded to the south by a low subglacial ridge which separates this feature from Bentley Subglacial Trench. A rude delineation of this subglacial basin was determined by several U.S. seismic parties operating from Byrd Station, Little America V, and Ellsworth Station during the 1950s and 1960s. It was named by the Advisory Committee on Antarctic Names (1961) for its locus relative to Marie Byrd Land and Byrd Station.