US Post Office-Warsaw is a historic post office building located at Warsaw in Wyoming County, New York. It was designed and built in 1934-1935 as a Works Progress Administration project, and is one of a number of post offices in New York State designed by the Office of the Supervising Architect of the Treasury Department, Louis A. Simon. It is a one-story, five bay steel frame brick structure on a raised reinforced concrete foundation in the Colonial Revival style. It was listed on the National Register of Historic Places in 1989.