The world number 9 however missed her start to the match, conceding a scathing 6-1 in 25 minutes against a Victoria Azarenka of great days.
Broken from the start of the second set by the Belarusian, Osaka raised the level of her game to win six of the last seven games of this round and win 6-3 in 40 minutes.
The former world number one made the break in the third game before erasing three breakout balls in stride.
She didn't tremble to go for her second title in New York: 1-6, 6-3, 6-3 after 1:50.
The Japanese won her third Grand Slam title after the 2018 US Open and the 2019 Australian Open, in as many finals.
The current world number 9 will find third place in the WTA rankings on Monday.
More info to come ...
Read also
Calendar / Results US Open