Reigning Wimbledon champion Barty won 31 of 32 points on first serve in a ruthless 6-3 6-4 victory over the 2020 Australian Open winner.
It sets up a tantalising last-four clash with Poland's defending champion Iga Swiatek, who is a frequent practice partner for Australian home favourite Barty.
Explaining her stunning serving performance, Barty said: "I think towards the end Sofia was kind of leaning one way or the other, and I was able to kind of get up and hit my spots."
Facing former French Open winner Swiatek will be a major early-season test for the world No.1, with the Warsaw-born 20-year-old fending off former grand slam winner Victoria Azarenka 6-3 2-6 6-1 in Friday's quarter-final.
The other semi-final in Adelaide will see Misaki Doi take on Elena Rybakina after both won in three sets to get there, seeing off Kaja Juvan and Shelby Rogers respectively.
Melbourne Park is staging two tournaments this week, and there is the prospect of a starry final in Melbourne Summer Set 1, with Naomi Osaka and Simona Halep both through to the last four.
No.1 seed Osaka beat experienced German Andrea Petkovic 6-1 7-5, while No.2 seed Halep had to scrap for a 6-2 5-7 6-4 win against Viktorija Golubic of Switzerland.
Osaka took inspiration from Petkovic's fight in the second set of their contest. She said: "It was really cool how she didn't give up for any point, so I just felt like I should do the same thing and see what happens."
Halep said her encounter with Golubic had been "really difficult", adding: "I didn't really trust that I can win this match, but I fought to the end, and I'm very proud of this."
Saturday's semi-finals of Melbourne Summer Set 2 will see Daria Kasatkina take on Amanda Anisimova, while Ann Li plays Aliaksandra Sasnovich.