Giorgi, the No.3 seed at the International-level event, played lights out from start to finish, holding all nine of her service games - and fighting off all three of the break points she faced. She ripped winner after winner off the ground to dominate the rallies, too, breaking the Radwanska serve three times.
The Italian won five games in a row and ripped one last forehand winner to finish it off, 6-4, 6-2.
"It was the best match I've played so far this week," Giorgi said. "I felt good. I was playing with confidence. I was really consistent and aggressive, and even if I made mistakes, I stayed focused."
Giorgi's win over the World No.9 was her sixth Top 10 win - she had one in 2012 (No.7 Sara Errani in Beijing), one in 2013 (No.8 Caroline Wozniacki at US Open) and three in 2014 (No.5 Maria Sharapova at Indian Wells, No.10 Dominika Cibulkova at Rome and No.8 Victoria Azarenka at Eastbourne).
Six Top 10 wins - and actually a winning 6-4 record against Top 10 players - is relatively unheard of for a player who has never been in the Top 30 herself, though that might change after this week.
The Italian will now have a shot at her first WTA title, and it would have some very special meaning, too, given she actually held match point in her first two WTA finals (Katowice and Linz last year).
Standing between her and her first WTA title is another WTA Rising Star seeking their first WTA title, Anna Karolina Schmiedlova. The No.8-seeded Slovak booked her place in the final earlier in the day with a one-hour, 15-minute, 6-4, 6-1 win over yet another WTA Rising Star, Alison Van Uytvanck.
"I was nervous before the match because it was the semifinals and Alison is a very good player," Schmiedlova said. "She has a really good serve and plays a lot of slice from the backhand, which I don't like so much, and a lot of drop shots too. Today I think she made a few mistakes in some of the important points, which gave me confidence, and I started playing better. I'm happy to get through."
Schmiedlova is into her second WTA final - she was a runner-up to Sara Errani at Rio this year.
Giorgi and Schmiedlova will be playing against each other for the very first time.