Russian Darya Pishchalnikova had thrown over 70 metres this season but was well down on that distance with 67.56 for the silver.
China's world champion Li Yanfeng was third with 67.22. Beijing Olympic champion Stephanie Brown Trafton of the U.S. finished eighth with 63.01.
Perkovic, who returned from a sixth-month doping ban this season, was the last to throw and spent the final round pacing the discus area nervously as her competitors each entered the circle.
Already sure of the title, Perkovic stepped on to the field urging the crowd to cheer her last throw, which only went to 64.03 before she burst into tears.