The type specimen was found by Auburn University geologist David King in eastern North America in July 1982. This dinosaur was named after the region of the eastern United States known as Appalachia, which also gave its name to the ancient island continent on which Appalachiosaurus lived. Both are named after the Appalachian Mountains. The generic name also includes the Greek word sauros (lizard), the most common suffix used in dinosaur names. There is one known species, A. montgomeriensis, which is named after Montgomery County in the U.S. state of Alabama. Both genus and species were named in 2005 by paleontologists Thomas Carr, Thomas Williamson, and David Schwimmer.