Located in Florida Bay, 4.5 miles north of the Saddlebunch Keys.
A survey map drawn by Charles Smith in 1872 shows Mallory's Key. U.S. Coast & Geodetic Survey chart #169 (1878) shows Mallory's Key. So named on U.S. Coast & Geodetic Survey chart #1251 (1932).
Named for the Mallory family, early settlers of Key West.