Osaka, 21, became the first tennis player from Japan to reach No. 1 in the rankings. She edged Czech tennis player Kvitova 7-6 (2), 5-7, 6-4.
Osaka held three match points in the second set at 5-3, love-40 as Kvitova, 28, served. But Osaka couldn’t close it out. Instead, she completely lost her way, dropping 23 of the next 27 points.
Kvitova was able to come back and go up 1-0 in the third.
The Japanese tennis player was seen yelling at herself, slamming a ball off the court and tugging at her pink visor. She left the court after the second set with a towel draped over her head.
However, Osaka was able to regroup just in time.
After Kvitova double-faulted to offer up a break point at 1-all, Osaka converted it with a cross-court backhand winner. There was still more work to be done, of course, and some additional drama when it began raining at the changeover right before Osaka tried to serve for the match at 5-4 in the third set.
Osaka added the Australian Open trophy to the one she collected in a U.S. Open final last September. However, in September the crowed jeered after runner-up Serena Williams was docked a game after arguing with the chair umpire Carlos Ramos. This time, there were cheers as Osaka accepted her trophy.
Kvitova, a two-time Wimbledon champion, was playing in her first Grand Slam final since she was injured in 2016 by a knife-wielding attacker. She underwent surgery on all of her fingers on her dominant left hand.
Osaka is the first woman to win two major championships in a row since Williams picked up four straight in 2014-15.
The Associated Press contributed to this report.
By Kathleen Joyce