Cape Darnley is the ice-covered cape forming the northern extremity of Bjerkø Peninsula at the west side of MacKenzie Bay. On December 26, 1929, Sir Douglas Mawson, from the masthead of the RSS Discovery while at 66°57'S 71°57'E, saw land miraged up on the southwest horizon. On February 10, 1931 he returned in the Discovery and was able to approach close enough to see the headland, naming it for E.R.