The Serb quelled a second set loss against her Polish opponent for the 6-2, 3-6, 7-5 victory, and Sunday will play in her seventh final this season.
"I started well in the first set," Ivanovic said. "The second set wasn't as good as my first serve percentage dropped, and Agnieszka was getting the balls really low and short. The third set was a bit up and down."
Ivanovic has a 4-2 record in 2008 finals.
In the other semifinal, Russian Vera Zvonareva, the No. 2 seed, defeated sixth-seeded Marion Bartoli of France 6-0, 6-1.
Sunday's Ivanovic-Zvonareva winner takes home a $95,500 champions check.
"Vera has been playing well the last couple of weeks, finishing runner-up at Moscow and qualifying for the Sony Ericsson Championships, so it will be a tough match," Ivanovic said.