Tiliqua gigas lives in Indonesia (Ambon, Ceram, Ternate, Halmahera, Mysol, Ke, Aru), Papua New Guinea, Jobi, the Admiralty Islands, New Britain, and the Bismarck Archipelago (Barbour 1912, JCVI/TIGR 2010).

According to Gorseman (1998), T. gigas is found in the easternmost part of Java, in Sumatra, on many of the Moluccas, the Kai Islands, the Tanimbar Islands, and Halmahera, on the entire southern and western coasts of Irian Jaya and Papua New Guinea, as well as the northeastern edge of Papua New Guinea.