Jabeur struck back to take a 4-2 lead but then looked nerve-wracked as errors poured from her racket and she lost five straight matches to miss the opening set.
Vondrousova, who had athletic tattoos on her arms, led 1-0, 40-0 in the second set and appeared to be cruising towards victory but Jabeur suddenly relaxed her shoulders and found her range.
It looked as if Jabeur was on the cutting edge of winning three straight matches, but Vondrousova never panicked.
Showing great court craft and subtle changes of pace, she bounced back to 3-3 and with Jaber’s mistakes back, broke serve at 4-4 to stand one game away from the title.
Reaching 40-0, she squandered her first game point on a double fault but hit a single to claim the title on the second time of order, appearing in disbelief.
The first player to reach two Grand Slam finals as an unseeded player, Vondrousova became the fourth Czech-born player to win the title in the professional era after Martina Navratilova, Jana Novotna and Petra Kvitova.