The two singers teamed up to sing a cover of "Don't Dream It's Over" to support Cyrus' new Happy Hippie Foundation. The video can be seen here.
"Soooooo thankful for Ariana Grande for being a part of the #backyardsessions!! You're the sweetest little #happyhippie bear-mouse ever! Loooooove you The Happy Hippie Foundation #HappyHippiePresents #dontdreamitsover," Cyrus wrote on Facebook.
Cyrus, 22, launched her foundation, which benefits homeless youth, earlier this year. She said during an appearance on "Good Morning America" that her work began last year, when she brought a homeless young man as her date to the MTV Video Music Awards.
"We started a year ago with Jesse and we were focused on the homeless youth in L.A. and different support groups in San Francisco,” she said. “Now, we’re going bigger and wanting to take on America. And by the end of it we’re going to be taking on the world.”
Grande, 21, has been very supportive, and shared a photo from their duet earlier this month.
"Congrats to my friend @mileycyrus on the launch of @happyhippiefdn!!! you are an [angel] on earth. i can't thank you enough for doing something so important and for having me be part of something so special," she wrote. "thank you for using your voice in such an incredibly positive and [healthy] way. here's to helping so many sweet babes in need. for more information follow @happyhippiefdn if you believe in fighting injustice / limiting labeling, assumptions, [judgment], challenging stereotypes, encouraging our fellow human beings to feel safe in their skin, and helping homeless youth. this work of yours is so incredibly important!!!! i love, appreciate and celebrate you."