The 23-year-old Australian took a break from the game in 2014 after finding the pressure too much and spent time playing professional cricket before returning three years ago ranked outside the top 600.
She has been on an upward trajectory ever since and was totally in control of this meeting of two first-time grand slam singles finalists, winning 6-1 6-3 in just an hour and 10 minutes.
Barty, who will be ranked second in the world on Monday, is the first Australian woman to win a slam singles title since Sam Stosur at the US Open in 2011 and the first in Paris since Margaret Court in 1973.
This was a crushing end to a superb fortnight for Vondrousova, who had hoped to emulate Jelena Ostapenko's achievement of two years ago by winning the title as an unseeded player, but she will be ranked 16th on Monday and will surely have more chances at slam level.
While this was not the final many would have predicted, it was a meeting between two of the most in-form players of 2019.
Barty has soared into the top 10 while Vondrousova, who began the year ranked 67, has won more matches since the Australian Open than any other woman.
Hanging around for an hour and a half while the delayed men's semi-final between Novak Djokovic and Dominic Thiem was completed would hardly have helped either of their nerves.
Vondrousova had begun very shakily in her semi-final against Johanna Konta, and it was the same again here, but this time she did not receive any help from her opponent.
Barty, who had been considered a potential slam champion on faster surfaces but not clay, was in the groove from the start, serving strongly and placing the ball confidently into the corners.
The Australian had been 5-0 up against Amanda Anisimova in the last four only to lose the first set but there was no sign of her letting her grip go here.
Vondrousova's touch-based, tactical game makes her a tricky opponent for lots of players but Barty plays a similar style and was not unsettled by the drop shots and lobs coming her way.
The Australian is one of the world's leading doubles players and won her first grand slam title in that format at the US Open last year with American Coco Vandeweghe.
Vondrousova desperately needed to get some kind of foothold in the match, and she dug in to hold for 1-2 in the second set.
She was at least doing a much better job of holding her serve but she was unable to make any headway on Barty's and at 3-5 found herself serving to stay in the match.
A netted forehand brought up a first match point for Barty, which she took with a simple smash before raising her arms in the air.
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