"It's something that I was waiting for more than 2013 maybe, so the pressure was pretty high before the second run," Worley said.
"But I managed to get to the end, I'm so, so happy."
Worley admitted to further nerves over an error high up a Corviglia course basking in bright sunshine that saw snow rapidly melting on the second run.
"Just a small mistake like this could be fatal," the 27-year-old acknowledged. "I tried to tell myself 'ok, now push harder and try to ski like I used to down the whole run'", she added.
Worley enjoyed a 0.38sec lead over the field after the first run and held her nerve on the second for a combined time of 2min 05.55sec.
American Mikaela Shiffrin, the double defending slalom champion, won silver, at 0.34sec, with Italian Sofia Goggia taking bronze (+0.74sec).
Worley, born to an Australian father and French mother, joins an elite band of racers to have won two giant slalom golds -- only Anja Paerson, Deborah Compagnoni, Mariele Goitschel and Vreni Schneider having previously achieved the feat.
She also won world giant slalom bronze in 2011 in Garmisch.