"The women who have invested in me growing up made me who I am today," Osaka posted on social media. "I don't know where I would be without them.
"Throughout my career I've always received so much love from my fellow female athletes so that's why I am proud to share that I am now a owner of the Courage."
Osaka, 23, was Forbes' highest-paid female athlete for 2020. She had $37.4 million in earnings last year, with $34 million from endorsements. She ranked No. 29 in earnings among all athletes in 2020.
She is the first investor in the Courage since owner Steve Malik bought and relocationed the NWSL franchise from Buffalo, N.Y., to Cary, N.C., in 2017.
"I am thrilled to welcome Naomi as an owner of the North Carolina Courage," Malik said in a news release. "Naomi embodies the values we have been striving to cultivate at our club, and she brings an invaluable viewpoint on topics beyond sports.
"I cannot think of anyone better to help us as we continue to make a difference in our community and inspire the next generation of women."
The Courage said that it also plans to incorporate Osaka into design decisions for the team in 2021.
"My investment in the North Carolina Courage is far beyond just being a team owner, it's an investment in amazing women who are role models and leaders in their fields and inspirations to all young female athletes," Osaka said.
"I also admire everything the Courage does for diversity and equality in the community, which I greatly look forward to supporting and driving forward."
The 2020 NWSL season was canceled due to the coronavirus pandemic. The Courage then posted a 4-0 record in the preliminary round of the Challenge Cup before a quarterfinal loss to the Portland Thorns. The Courage later had a 1-1-2 record in the four-game NWSL Fall Series.
The 2021 NWSL Challenge Cup scheduled to start on April 9. Players report to camp on Feb. 1. The regular season starts on May 15.
The 2020 Courage roster featured several United States Women's National Team and international stars, including: Abby Dahlkemper, Lynn Williams, Jessica McDonald, Stephanie Labbe and Debinha.