She outclassed unseeded Shelby Rogers under lights at the Arthur Ashe Stadium.
Meanwhile, Alexander Zverev came from behind against Croatia's Borna Coric in a three-hour battle, advancing to his first ever US Open semi-final.
Here are the key moments.
Naomi Osaka completely owned the match, defeating Rogers 6-3, 6-4.
Osaka, who (in 2018) became the youngest champion in Flushing Meadows since Maria Sharapova (2006), smashed five aces in the 38-minute opening set.
Moreover, she dropped mere nine points on her serve.
The two-time Slam champion struck early in the second set too, having eventually won in 1 hour and 19 minutes.
Alexander Zverev recovered from a set down to win a gruelling encounter against Borna Coric.
Having won the four-set battle (1-6, 7-6, 7-6, 6-3), the German rolled into his maiden semi-final at the US Open.
Despite looking rusty, Zverev was able to seal the match at the end.
Notably, Coric held a 3-1 edge in his head-to-head with Zverev, prior to this match.
Pablo Carreno Busta survived brilliance of Denis Shapovalov to reach the US Open semi-finals for the second time on Tuesday night in New York.
Although the Spaniard was under pressure from Shapovalov's aggressive attack, he was able to win two crucial tiebreaks in the second and third set respectively.
Even after losing a bagel (fourth set), Busta won 3-6, 7-6, 7-6, 0-6, 6-3.
Among other women, Jennifer Brady also made it to the semi-finals.
Playing in her first ever Grand Slam quarter-final, Brady scored a fifth consecutive straight-set US Open victory.
The American, who was seeded at a Slam for the first time, trounced number 23 seed Yulia Putinsteva 6-3, 6-2.
Interestingly, Brady became the first former college athlete to reach US Open semi-finals since 1987.
Daniil Medvedev and Elise Mertens are the only other singles players yet to drop a set this fortnight, however, Brady has played one more match than them. Women's doubles semi-finalists Nicole Melichar and Xu Yifan are also members of the elite club.
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