The 23-year-old won her fourth Slam from the last eight she has contested with the comfortable 6-4, 6-3 victory in 77 minutes at Rod Laver Arena.
She becomes only the third player after Monica Seles and Roger Federer to win their first four Major finals, and will now rise to second in the world rankings.
The Japanese sensation is now seen as the dominant force in women’s tennis, a view shared by seven-time Slam winner Mats Wilander, who believes Osaka can win 10 Grand Slams.
“I’m taking it in sections. For right now, I’m trying to go for five,” Osaka said, when asked about Wilander’s comment.
“After five I would think about maybe dividing the 10, so maybe seven or eight.
“I don’t like to take things big-picture. For me, I like to live in the moment.
“It’s an honour that he said that. But I don’t want to weigh myself down with pressure and expectations.”
She has proven to be irresistible on hard courts after now winning twice at Melbourne Park and Flushing Meadows.
But she has struggled elsewhere, having never made it past the third round on the French Open’s clay or Wimbledon’s grass courts.
“I feel like I have to get comfortable on those surfaces,” she said.
“I didn’t grow up playing on grass at all.
“I honestly think I’d have better luck on clay, because I think last year I didn’t play bad at all.”
However, when asked where she was most likely to win her first non-hard-court Grand Slam, Osaka said: “Hopefully clay because it’s the one that’s sooner.”
As her achievements grow, Osaka said she simply hoped to inspire the next generation.
“Hopefully I play long enough to play a girl that said that I was once her favourite player,” she said.
“Unfortunately I didn’t get to play (two-time Major champion) Li Na.
“I just think that’s how the sport moves forward.”