In an enthralling match, Kvitova was able to save three championship points at the end of the second set, with Osaka seemingly struggling to get over the line. However, the 21-year-old was able to regroup magnificently in the decider and secure the victory.
Success for Osaka makes it back-to-back Grand Slam titles, having won the U.S. Open in 2018. The win also means she moves to the top of the WTA rankings for the first time.
Here's a look at how social media reacted to an incredible final and another remarkable triumph for Osaka.
World Reacts to Outstanding Osaka
At the end of a punishing contest, the relief was clear to see from Osaka:
Having been in total control for the majority of the match, it was a surprise to see the youngster crumble at the end of the second set, with Kvitova stepping up her form and saving three match points.
The manner in which the new world no. 1 regrouped was indicative of someone special.
As the Live Tennis Twitter account relayed, it's been a long time since a player matched Osaka's start to Grand Slam success:
Unsurprisingly Osaka received a rapturous reception from those in attendance at the Rod Laver Arena in Melbourne, making it an atmosphere markedly different when compared to her previous win at the U.S. Open:
BBC Sport's Russell Fuller said the resolve on show at Flushing Meadows came to the fore again in this encounter:
Twitter was full of praise for the performance of Osaka, too. Martina Navratilova, an 18-time Grand Slam singles champion, was one of the first to offer her thoughts on the match, as did WTA star Alize Cornet:
Osaka's coach Sascha Bajin was quickly on to social media to praise his player, too:
Although Osaka was rightly the recipient of plenty of plaudits, there were also a lot of positive words for Kvitova.
This was the first time she had been in a Grand Slam final since 2014 and her first since an intruder slashed her left hand with a knife at her home in 2016. After the attack, the Czech said she was "fortunate to be alive," per David Ornstein of BBC Sport.
Tennis journalist Reem Abulleil expressed her admiration for both Osaka and Kvitova following this titanic tussle:
Reem Abulleil @ReemAbulleil
When I grow up I wanna be like Naomi Osaka. The way she regrouped after that 2nd set is a skill I am yet to acquire so far in my life. When I grow up I wanna b like Petra Kvitova. The way she turned trauma into triumph is something that inspires me every day! Take a bow ladies!
The crowd also rallied behind the runner-up as she discussed the attack in the post-match interview:
Still, the day belonged to Osaka, who has made remarkable progress in the past year. At the 2018 Australian Open, she was ranked 72nd in the world; at the end of the 2019 edition, she's secured two Grand Slams and the world no. 1 spot.
The assurance and quality she has been able to showcase on the biggest stages in tennis means she will be difficult to knock off that position. For the rest of this year and beyond, she appears to be a competitor who will be successful on many more days like this.