The four-time Grand Slam winner, whose father Leonard Francois is Haitian, said that she will give all her proceeds from the upcoming Cincinnati Masters to help the Caribbean nation.
"Really hurts to see all the devastation that's going on in Haiti and I feel like we can't catch a break," Osaka wrote on Twitter.
"I know our ancestors blood is strong we’ll keep rising."
At least 724 people died and 2,800 were injured after a major earthquake struck southwestern Haiti, according to the country's authorities.
Osaka is back playing in Cincinnati one year after she withdrew from her semi-final with Elise Mertens to join a wave of sports boycotts across the United States calling for social justice and an end to police violence.
Tournament organisers backed her stance by postponing play for a day, after which she defeated the Belgian before a hamstring injury forced her to pull out before the final with Victoria Azarenka.
Two weeks later, Osaka and Azarenka met in the final of the US Open with the Japanese winning in three sets to claim her third Slam title.
The 23-year-old is seeded second in this year's event, and could face 17-year-old American sensation Coco Gauff in the second round.