Naomi Osaka was born on October 16, 1997, and she shares her surname with her birthplace: Osaka, Japan. Naomi's father, Leonard Francois, was born in Haiti, and her mother, Tamaki Osaka, was born and raised in Hokkaido, Japan, according to a 2018 profile of the athlete in The New York Times.

Francois was a college student in New York when he traveled to Sapporo around 1990, at a time when Tamaki was attending high school in the same city, Hokkaido's capital. The duo secretly dated for several years before Tamaki, in her twenties by that point, disclosed the relationship to her father, who was ready to talk to her about matchmaking ahead of an arranged marriage. Facing outrage from her father, Tamaki and Francois moved to Osaka, where they had their daughters, Naomi and Mari Osaka.

Stuart Duguid, Naomi's agent at I.M.G., reflected on his client's biracial status in 2018, telling the Times he hopes Naomi has "changed cultural perceptions of multiracial people in Japan," as well as "opened the door for other people to follow, not just in tennis or sports, but for all of society."