Amelia Island is located off the coast of Florida, north of the St. John's River and south of the Georgia - Florida state line.

It is the southernmost of the Sea Islands, which consist of over 100 barrier islands that are located between the Santee River in South Carolina and the St. John's River in Florida. It is also the northernmost of the barrier islands of Florida.

The city of Fernandina Beach is at the northern end of the island, and the Amelia Island State Park is at the southern end.