Having trailed 5-1 in the decider, Italian Giorgi fought back brilliantly to force a tie-break in the WTA International hard-court event's showpiece.
But Pliskova regained the momentum in the shoot-out as the Czech continued her fine recent form, claiming a 6-7 (4-7) 6-3 7-6 (7-4) victory in what was her third final in four weeks.
After losing to Sabine Lisicki in the Hong Kong Open final and beating Varvara Lepchenko to win the Korea Open, Pliskova headed into the contest as favourite against her 22-year-old opponent.
However, Giorgi displayed stubborn resistance early on and recovered from a break down in the first to take the opener on a tie-break.
That appeared to spark Pliskova into life, though, and Giorgi could do little to prevent the world number 30 from racing into a 4-0 lead before sealing the second set.
And the contest appeared to be all but over when Pliskova assumed a similarly dominant position in the third, only for Giorgi to reel off five straight games and take a 6-5 lead.
Yet Giorgi - who had suffered heartbreak in her only other WTA final back in April, losing to Alize Cornet in three sets at the Katowice Open after leading 5-4 in the decider - once again let a prospective winning position slip.
Pliskova saved a match point to set up a tie-break, which she dictated to ensure triumph and the third WTA title of her career.