The Florida Platform is a flat geological feature that underlies all of Florida and southern Alabama and Georgia and their adjacent continental shelves. The basement of the platform, composed of igneous, metamorphic, and sedimentary rocks, was originally part of the African continent that became attached to the North American continent in the Jurassic geological period. The basement rocks are overlain by up to 5 kilometres (3.1 mi) of evaporite, carbonate, and siliciclastic sedimentary deposits that are primarily of marine origin.

The Florida Platform is a large, level, and relatively stable platform of sedimentary strata on the trailing or eastern edge of the North American continent, extending between the basins of the Gulf of Mexico and the Atlantic Ocean. It underlies all of Florida and its adjacent continental shelves, as well as the southern parts of Alabama and Georgia. Most of the basement of the platform was originally part of Africa that became attached to North America during the Ordivician Period as the supercontinent of Pangaea formed. The platform separated from Africa as Pangaea broke up in the Jurassic, remaining attached to North America. The Florida Platform remained submerged for most of the Cenozoic Era, and the sedimentary strata of the platform are primarily of marine origin.

The basement of the Florida Platform comprises igneous, metamorphic, and sedimentary rocks of Proterozoic, Paleozoic, and Triassic age. The top of the basement of the platform is marked by an unconformal surface of pre-Middle Jurassic age overlain by evaporite, carbonate, and siliciclastic deposits of Middle Jurassic to Holocene ages. The top of the basement is approximately 915 metres (3,002 ft) below mean sea level (MSL) in the north-central Florida peninsula, and slopes downward on the east towards the Atlantic Ocean basin, on the west towards the Gulf of Mexico basin, and on the south towards the South Florida Basin, reaching 5,180 metres (16,990 ft) below MSL in southern Florida.

The basement rocks of the Florida Platform are divided into two regions by the Bahama Fracture Zone, which runs northwestward from the Bahamas across southern Florida under the Gulf of Mexico and the extreme western end of the Florida panhandle in to Alabama. The fracture zone is also known as the Jay Fault in Florida and the Pickens-Gilberton Fault in Alabama. Northeast of the Bahamas Fracture Zone is the Suwannee terrane, a crustal fragment that originated on the coast of what is now West Africa when it was part of Gondwana.

Southwest of the Bahama Fracture Zone in the southern part of the Florida peninsula the basement is primarily composed of the Mesozoic-age South Florida Volcanic Rocks. Across the West Florida Continental shelf and southern Florida southwest of the Bahama Fracture Zone there are several basins and arches at the top of the basement rocks discernible via seismic imaging. The Apalachicola Basin on the continental shelf is offshore of the Apalachicola Embayment or South Georgia Rift. It is bordered on the southeast in turn by the Middle Ground Arch, which extends across the Bahama Fracture Zone under Apalachee Bay, The Tampa Basin, the Sarasota Arch, and the South Florida Basin.

The Florida Platform originated in Gondwana in the early Paleozoic. Data from paleontology, isotope geochemistry, and paleomagnetism studies indicate that the platform was part of the western African continental margin near Senegal. Boreholes in northern Florida that reached sandstones and shales of Paleozoic age have recovered fossils of graptolites, brachiopods, trilobites, crinoids, molluscs, conodonts, palynomorphs, and chitinozoans. The faunal assemblages resemble African or South American assemblages, but none have resembled any North American assemblage. Bore holes have also penetrated granite and other volcanic rocks. The Tallahassee-Suwannee terrane that forms the basement under northern Florida and southern Georgia (northwest of the Bahama Fracture Zone) contains rhyolitic rocks that correlate geochemically with rocks found in locations along the western margin of Africa. The St. Lucie metamorphic complex matches rocks of the Rokelide Orogen in Guinea. The Osceola Granite resembles the Coya Granite in Senegal. The Suwannee Basin sedimentary rocks have been correlated with those of the Bove Basin in Guinea-Bissau; the two features are likely remnants of an extensive basin.

In the late Paleozoic Era, Laurentia (the core of what is now North America) converged on Gondwana, closing the Iapetus Ocean and creating the Pangaea supercontinent. The part of Gondwana facing Laurentia included what are now western Africa and northern South America. The collision created strike-slip faults in Gondwana as blocks of crust moved in response to irregularities in continental margins. There are several possible faults from this period in the basement of the Florida Platform, the most prominent being the Bahama Fracture Zone. The Brunswick Magnetic Anomaly, consisting of a northern negative component and a southern positive component, runs east-west across southern Georgia and Alabama. The anomaly is commonly believed to mark the boundary between the Florida Platform and the rest of North America. An alternative explanation for the anomaly is that the North American Plate was subducted under Gondwana as the Iapetus Ocean closed, and that the anomaly marks the lower end of the subducted North American lithosphere under the Tallahassee-Suwannee terrane (the northern part of the Florida Platform), the northern boundary of which may be as much as 100 kilometres (62 mi) north of the anomaly. Another proposal is that the Brunswick Magnetic Anomaly was a Mesozoic rift basin. It has also been proposed that the Florida Magnetic Anomaly, crossing the Florida peninsula approximately from Volusia County to Hernando County, marks the suture between North America and the Florida Platform.

Reconstructions of Pangaea place the Florida Platform at the junction of the African, North American, and South American continents. A system of rifts that would eventually produce the Atlantic Ocean began opening along the pre-Pangaea continental margins during the Triassic. The rifting is believed to have been initiated by hot spots, including one near the southern end of the Florida Platform. Isotopic signatures of the South Florida Volcanic Rocks indicate they were produced by a hot spot. The South Georgia Rift, a graben, started to form across what is now southern Georgia (along the pre-Pangaean margin between Africa and North America), but stopped and became an aulacogen, a failed arm of a triple junction. The rifting shifted, separating the Florida Platform and the Bahamas Banks from Africa and South America.