"This means we have a new area" of local transmission, Governor Rick Scott said at a press conference.
The Health Department confirmed that five individuals have been confirmed as cases of local Zika transmission in the Miami Beach area.
Florida now has 36 cases of locally transmitted Zika virus, which is typically spread by mosquitoes but also by sexual contact.
The size of zone in Miami Beach where active Zika transmission is occurring is just under 1.5 square miles (3.9 square kilometers).
Zika is particularly dangerous to pregnant women because it raises the risk of birth defects.