After nervously hesitating in ticking off thankyous, Osaka said: "This is probably going to be the worst acceptance speech of all time." She singled out Kasatkina and apologised for not starting her speech with her, while Osaka's own team got a memorable shout out.
"I would like to thank Dasha for being super nice and also being a really cool person to play against," Osaka said. "I'm pretty sure we're going to play a lot of finals later.
"I would also like to thank Dasha's team because they're super nice too.
"I would like to thank my team for putting up with me and ... yeah that's basically it, and also supporting me."
Osaka thanked her Haiti-born father and Japan-born mother, who weren't on hand, as well as the "super awesome" ball kids. The crowd was in stitches any time Osaka finished a sentence.
The 20-year-old visibly flinched when streamers were shot off. She stepped gingerly toward the crystal trophy resting on a stand and delicately placed her hands on each side of it. She shook her head and declined to pick up the heavy prize. "I think that's it," she told the crowd.
Osaka's victory capped a run that included beating two-time winner Maria Sharapova, world No. 5 Karolina Pliskova and top-ranked Simona Halep during the two-week tournament. She dropped one set in seven matches.
Osaka will rise to a career-high No. 22 in Monday's WTA Tour rankings.
In a match-up of 20-year-old rising stars, Osaka needed just 70 minutes to dispatch world No. 19 Kasatkina, who had an equally impressive showing in the desert. Osaka closed out the biggest win of her career with a backhand winner that ticked the baseline.
She earned $AUD1.9 million for the victory, nearly doubling her career winnings to date. She is the first unseeded winner since Kim Clijsters in 2005 and the second-youngest since Ana Ivanovic in 2008.