The linen garments were found in the remains of Lengberg Castle in eastern Tyrol. They resemble modern bras in that they have two distinct cups, and have decorative needle lace that would not have been visible when worn under a dress.
The bras were among 2,700 textile fragments found during archaeological investigations of the castle by a team from the University of Innsbruck, which began in 2008.
Carbon dating has now confirmed that the garments date back to the 15th century, the researchers said.
Varying accounts exist of who invented the modern bra, but Sigmund Lindauer, who came from a German family of corset makers, patented an elastic version in 1913 and began mass producing the garments.
The metal shortages of World War Two helped hasten the demise of the corset.
