King Peninsula is an ice-covered peninsula, long and wide, lying south of Thurston Island and forming the south side of Peacock Sound, Antarctica. It projects from the continental ice sheet and trends west between the Abbot Ice Shelf and Cosgrove Ice Shelf to terminate at the Amundsen Sea. The feature was photographed from the air by U.S. Navy Operation Highjump, 1946–47, and was plotted from these photos as a long island, or possible peninsula. Photos taken by the U.S. Navy in 1966 show it is a peninsula.