She defeated defending US Open champion Angelique Kerber in the first round of the 2017 US Open.
Osaka was born in Osaka, Japan, to a Haitian father and a Japanese mother. She has an older sister, Mari, who is also a professional tennis player.
Osaka made her main draw WTA tour debut at the 2014 Bank of the West Classic, having firstly entered the qualifying tournament and defeating Alla Kudryavtseva and Petra Martić for a spot in the main draw. She was then pitted against 2011 US Open champion Samantha Stosur and came from a set down to defeat the Australian in a match lasting 2 1/2 hours. It was Osaka's first main draw match win at the WTA level.
During the 2015 WTA Finals she won the Rising Stars Invitational exhibition tournament, defeating Caroline Garcia in the final.
In her grand slam debut, Osaka reached the third round of Australian Open as a qualifier defeating Donna Vekic and 18th seeded Elina Svitolina in straight sets. She ended up losing to former champion Victoria Azarenka in straight sets. During the clay season, Osaka reached the third round of the French Open. She defeated 32nd seed and future champion Jeļena Ostapenko and Mirjana Lučić-Baroni both in straight sets. She then lost to former finalist and 6th seed Simona Halep in three sets, despite capturing the first set.
After an injury forced her out from participating in Wimbledon, Osaka reached the third round at the 2016 US Open. She defeated 28th seed Coco Vandeweghe coming from a set down and she also defeated Duan Yingying in straight sets before falling to American Madison Keys 5-7, 6-4, 6-7 (3-7). She had led 5-1 in the third set.
She started off the fall Asian swing competing at the 2016 Japan Women's Open, where she comprehensively beat Anett Kontaveit in the first round before falling to Zhang Shuai in straight sets. The next week saw Osaka's main breakthrough arrive at the 2016 Toray Pan Pacific Open, where she was given a wildcard and went on to defeat the likes of fellow countrywoman Misaki Doi, Dominika Cibulkova, Aliaksandra Sasnovich, and Elina Svitolina to reach her first WTA final. In the final, she fell to former World No. 1 Caroline Wozniacki in straight sets. With this result, Osaka moved into the Top 50 of the WTA rankings.
Osaka was voted the newcomer of the year in the 2016 WTA Awards.
At the Australian Open, Osaka won her first round match before losing to Johanna Konta in straight sets. She also lost in the second round of the Dubai Tennis Championships to Christina McHale.
She had multiple second-round and third-round losses at Indian Wells, the Miami Open, and the Volvo Car Open. She qualified for the Women's Stuttgart Open before losing to Konta again in the first round. She was unsuccessful in the rest of her clay season.
Osaka lost in the first round of the Nottingham Open, in straight sets. She was able to win a match at the Birmingham Open before losing to Lucie Safarova in the next round. She also lost to Caroline Wozniacki in straight sets at the Eastbourne International tournament.
At Wimbledon, Osaka defeated Sara Sorribes Tormo and Barbora Strýcová before losing to Venus Williams in the third round.
At the US Open, she made the biggest win of her career, defeating defending champion Angelique Kerber in the first round. She then defeated Denisa Allertová in three sets before falling to five-time Grand Slam quarterfinalist Kaia Kanepi 3-6, 6-2, 5-7.
Osaka is an offensive baseliner. She is able to hit winners off both sides. She likes to attack with her big forehand, but she can also plant her feet and rip her backhand for winners as well. Her serve is consistent and very strong - up to 125 miles per hour (201 km/h) and can produce weak balls to hit winners off of. Osaka prefers to be attacking and is not as comfortable on defense.