On September 21, 1964 the Florida Board of Parks and Historic Memorials (FBPHM) acquired an approximately 356 acre property that constituted the initial area of Grayton Beach State Park.
There were additional land acquisitions, for the parks use and preservation, in 1985, 1993 and 1995.
The park's name comes from neighboring Grayton Beach, one of the oldest townships along the Gulf of Mexico in Walton County.
Grayton Beach State Park was dedicated and opened in 1968. The park borders the township on all sides except to the south which features the Gulf of Mexico.