Jabeur now has a Tour-leading 48 wins this season as she tries to capture her second career title after winning a tournament earlier this year in Birmingham.
"My game hasn't changed," she said. "I want to play the slice, drop shots and be good on the forehand. I am improving on a lot of things,"
Jabeur, of Tunisia, will face either Paula Badosa or 10th seeded Angelique Kerber for a spot in the final. Kerber is the highest seed left in the draw after a string of upsets earlier in the week.
Jabeur's win guarantees she will move into the top 10 in the world rankings for the first time in her career.
"It is amazing. I have been working so hard. At the end of last year I said I wanted to be in top 10. People doubted me. I have been working so hard," she said.
The combined WTA and ATP Masters event is normally held in March, but returned this fall after a two-and-a-half-year hiatus due to the global coronavirus pandemic.
Jabeur has now beaten Kontaveit three out of the four times they have played, including a victory in a tight match in Cincinnati this summer.
Kontaveit, of Estonia, took that loss and used it as a learning experience, winning 16 or her next 17 matches including two titles in Cleveland and Ostrava, Czech Republic.
Jabeur got the first service break in the third game of their quarter-final to go up 2-1. She broke Kontaveit in the fifth and again in the 11th game to take a 6-5 lead and a chance to serve out the first set.
In the second set, the players stayed on serve until the seventh game when Jabeur broke to go up 4-3. Jabeur held serve and then broke Kontaveit again to win 6-3 and clinch the match on the main stadium court.