Osaka, 22, beat the 28th-seeded Brady 7-6 (1), 3-6, 6-3 to return to the final at Flushing Meadows just two years after winning the U.S. Open championship.
"It means a lot for me. I kind of consider New York my second home," said Osaka, who was born in Japan and moved to the United States as a child. "I kind of love the atmosphere, even though there's no people here. I feel like this court kind of suits me well."
Osaka and Brady combined for 70 winners -- 35 each -- to only 42 unforced errors. Brady, a 25-year-old from Pennsylvania, had never been past the fourth round of a Grand Slam tournament before this week.
Osaka will face either 23-time major champion Serena Williams or two-time major champion Victoria Azarenka in Saturday's final. Williams entered that semifinal matchup with an 18-4 record over Azarenka, including a 10-0 mark in Grand Slam tournaments.