World No. 3 Osaka beat Brady 6-4, 6-3 at the Rod Laver Arena in Melbourne to claim the fourth Grand Slam title of her career.
The 23-year-old now has two Australian Open-2019 and 2021-and two US Open titles-2018 and 2020-to her name.
Brady, 25, who was playing her first Grand Slam final, was gracious in defeat, congratulating Osaka and terming her "an inspiration."
"[...] Another Grand Slam title, she's such an inspiration to us all and what she is doing for the game is amazing... I hope young girls at home are watching and inspired by what she's doing," she said.
Due to COVID-19 restrictions, a limited number of spectators were in attendance for the final, and the champion made it a point to make them feel special.
"Thank you for coming and watching. To have this energy really means a lot. Thank you so much. Thank you for opening your hearts and arms towards us," said Osaka.
"I feel like playing a Grand Slam right now is a privilege, and thank you for this opportunity."
The Japanese star will go home with the 2021 Australian Open trophy and 2.75 million Australian dollars (over $2.1 million) in prize money, while Brady pocketed 1.5 million Australian dollars (over $1.1 million) and got the first silver shield of her career.
