The 21-year-old from Japan, the first Asian man or woman to top the singles rankings, built on her maiden title at the US Open with a 7-6 (2) 5-7 6-4 victory to make it back-to-back slam successes.
Judging by what will surely be the first two of many slam finals, Osaka does not do routine. But, while her victory over Serena Williams in New York was all about controversy and meltdowns, this time the drama was all on the scoreboard.
At a set and 5-3 with Kvitova facing three match points, Osaka looked poised to stroll over the finish line only to lose four games in a row and the second set.
She had lost her head, too, but one of the most impressive things about her this fortnight has been the way she has overcome every mental hurdle placed in front of her and so it proved again.
Kvitova, who would also have become number one with victory, was playing in her first grand slam final since winning her second Wimbledon title in 2014 and only two years after the knife attack at her home that put her career in the balance.
The Czech had won her last eight finals and more than played her part in a generally high-quality encounter but in the end had no answer.
Osaka and Kvitova are two of the biggest hitters on the women's tour and long rallies were scarce as both looked to unleash at the first opportunity.
Osaka came under pressure at 2-2 and 3-3 but saved a combined five break points, while also seeing a break point on the Kvitova serve well saved by the Czech.
Somewhat strangely, the pair had never faced each other before, and Osaka's lack of experience against top-class left-handers was one of the match-up's unknown factors.
Osaka struggled to read Kvitova's serve initially but picked up the pace in the 12th game, forcing two set points. She could not take either, though, Kvitova producing a tremendously gutsy forehand to save the first and then a big serve on the second.
However, the Czech was simply outplayed in the tie-break, Osaka powering a return onto the line for a winner on the second point and not looking back.
Given Osaka had won her last 59 matches when taking the first set, the size of Kvitova's task was clear, but the 28-year-old responded well and secured the first break of the match on her seventh chance.
However, a missed opportunity to make it 3-0 looked very costly as Osaka won five of the next six games. When she won the next three points to bring up three match points, it appeared the trophy was hers.
But Karolina Pliskova's win over Serena Williams from 1-5 and match points down showed that a tennis match is never over until the final ball is hit, and this time it was her fellow Czech mounting the unlikely comeback.
Osaka was struggling to hold back tears as she left the court for a bathroom break but not for no reason has she now won 60 straight matches when claiming the first set.
Ending Kvitova's run of five straight games was crucial and, when Osaka powered a backhand full of anger and frustration past Kvitova to break for 2-1, the power had shifted once more.
Stepping up to serve for the match for a second time, Osaka's demons were nowhere to be seen and she clinched her fifth match point to ascend to the throne as the new queen of tennis.