St. Joseph Bay is a bay on the Gulf Coast of the U.S. state of Florida, located in Gulf County between Apalachicola and Panama City. Port St. Joe is located on St. Joseph Bay.
St. Joseph Bay is bounded on the east by the mainland, on the south by Cape San Blas, and on the west by the St. Joseph Peninsula. The north end of the bay is a relatively narrow opening to the Gulf of Mexico. The bay is approximately 15 miles long north to south, and 6 miles wide at its widest point. The St. Joseph Peninsula forms the T.H. Stone Memorial-St. Joseph Peninsula State Park, while the bay itself includes the St. Joseph Bay State Buffer Preserve and the St. Joseph Bay Aquatic Preserve.