The seventh-ranked Jabeur, a three-time Grand Slam finalist, saved her best performance of the tournament for the final and raced to victory in 78 minutes.
"I felt tactically I played very well. I had an advantage in that I had more experience than her to manage certain points," Jabeur said. "Playing a final here is more relaxed than playing a Grand Slam final, but I think it will help me gain confidence more and to help me manage the pressure and stress."
The Tunisian player had 18 winners to 10 unforced errors while saving all three break points she faced, denying the 19-year-old Shnaider any chance to get a foothold in the match.
This was the 85th-ranked Shnaider's first career final in just her ninth WTA tournament main draw. One year ago, she was ranked No. 220 and beginning her freshman year at NC State.
Pegula has lost just nine games in her three matches and will meet eighth-seeded Veronika Kudermetova in Sunday's final.
"When you're top-ranked, I think it just depends on how you play that day and how you execute your game plan, and some days it's better than others," Pegula said. "I think the faster courts here probably help me a little more than the slower surfaces I've played her [on] in the past, so I tried to take advantage of that."
In the earlier semifinal, Kudermetova edged past Anastasia Pavlyuchenkova 7-6 (6), 6-7 (2), 6-3.