The clip, which has gone viral since being posted on YouTube on October 7, features cancer patients and staffers from the hospital's Unit 5 singing along to Brave.
"There's a video that's kind of gone viral online of a children's cancer ward in Minnesota," Bareilles said. "The staff put together this video that was very similar to the music video of Brave and it's heart wrenching and gorgeous and beautiful and heartbreaking at the same time…It's a message I'm so happy to be the voice for."
The track, with lyrics that encourage listeners to "say what you wanna say" and to "be brave," became something of a gay anthem since it came out in May. The song was co-written with fun's Jack Antonoff, and according to Bareilles it came from a really "pure place, a really vulnerable place" and was inspired by friends who were struggling to come out.
The singer added that she was constantly listening to stories about how the song empowered people to come out.
You can check out Bareille's official Brave video and the Amplatz Children's Hospital cover below.