Jabeur, the primary Arab lady within the prime 10, received 7-5, 0-6, 6-3 for her second profession title.
She was enjoying in her sixth profession last and first since a runner-up end in Charleston final month.
Pegula, a one-time tour winner, will attain a career-high No. 11 rating on Monday.
Jabeur improved to 3-2 in head-to-head conferences towards Pegula.
The Related Press contributed to this report.