Having beaten Russian qualifier Anna Kalinskaya in the first round on Tuesday, Giorgi, ranked 78, took a tight opening set 7-5.
Local favourite Barty hit back to win the second set 7-5 before stepping up a gear to romp home 6-1 in the decider.
Jewish hopes in the Singles event now rest on the shoulders of Diego Schwartzman of Argentina.
He has reached round three where he faces Alexandr Dolgopolov. The winner could face Rafa Nadal in round four.