The player, 30, got engaged to girlfriend Sera Cahoone and posted the news to Instagram on Friday.
Cahoone, a singer-songwriter, attended the ESPYs earlier this month with the World Cup champ, who posted a cute shot from the evening to Instagram.
Rapinoe came out as gay publicly in 2012, telling OUT Magazine, "I feel like sports in general are still homophobic, in the sense that not a lot of people are out," she says. "I feel everyone is really craving people to come out. People want – they need – to see that there are people like me playing soccer for the good ol' U.S. of A."