Lucia Bronzetti downed Valentini Grammatikopoulou to seal Italy's place in the final of the inaugural United Cup.
Despite losing to Poland in their City Final in Brisbane, Italy claimed a place in the Sydney play-offs as the best-placed runner-up.
Having led 2-0 overnight, Italy were pegged back by Stefanos Tsitsipas' battling 4-6 7-6 (7-2) 6-4 win over Matteo Berrettini.
That put the pressure on Bronzetti's meeting with world number 199 Grammatikopoulou.
Yet despite losing her two previous matches against Grammatikopoulou, world number 54 Bronzetti made no mistake, cruising to a 6-2 6-3 victory.
Italy will now face the United States, who beat Poland 5-0 in their semi-final, in the final on Sunday.