Windley Key is an island in the upper Florida Keys in Monroe County, Florida, United States.
U.S. 1 (the Overseas Highway) crosses the key at approximately mile markers 84—85.5, between Plantation Key, to the NE, and Upper Matecumbe Key, to the SE.
All of the key is within the Village of Islamorada as of November 4, 1997, when it was incorporated.
Windley Key is home to Theater of the Sea, a popular tourist attraction since 1946.
The Windley Key Fossil Reef Geological State Park and the popular Holiday Isle resort are also on the island.