they have announced their engagement, four years after meeting at the 2016 Olympic Games
Two-time Women's World Cup winner Rapinoe, who was influential in last year's triumph at the finals in France, met Bird at the 2016 Olympic Games in Rio.
They announced they were a couple in July 2017, and Bird has now posted a picture on Instagram of Rapinoe putting a ring on her left hand.
Speaking to ESPN three years ago, Rapinoe explained how they found love, saying: "We have a lot in common and just sort of clicked. I joke she is my number one go-to-for-advice person. She's just so level-headed."
Joe Biden among the first to offer congratulations. Tennis great Billie Jean King sent wishes to the couple, with Chelsea Clinton also congratulating them, as did football's US Women's National Team and the WNBA's Seattle Storm.
US presidential candidate Biden wrote on Twitter: "Love will always win. Congratulations, @S10Bird and @mPinoe!"
Earlier this year, Rapinoe offered to be the running mate for Biden, the Democratic Party's candidate.
She drew the ire of incumbent US president Donald Trump having said she had no intention of visiting him if the USA won last year's Women's World Cup.