Five-eighth Michael Morgan also grabbed a first-half brace as the Kangaroos, winners of 10 of the 14 versions of the tournament, ran in eight unanswered tries to set up a semi-final against New Zealand or Fiji in Brisbane next week.
Cameron Smith orchestrated Australia's attack with his usual efficiency from hooker and converted all but the last of the tries, while fullback Billy Slater made a typically lively contribution and grabbed a record-equalling 14th World Cup try.
