The "We Can't Stop" singer went all out promoting her little sis, Noah Cyrus, at Sunday's iHeartRadio Music Awards, introducing the 17-year-old artist while wearing an "I Heart Noah" shirt with a homemade sign to match.
Noah took the stage with Labrinth to perform her song, "Make Me (Cry)," while Miley moved to the groove in the audience.
ET caught up with Noah before the show, who teased her sister's loving attire.
"I can't wait for everybody to see her outfit," she shared. "She has surprised me with the funniest, most amazing thing in the world, I love it so much. She's been nothing but supportive for me so I can't wait to have a sissy night with her."
"I'm so excited [to be here]," Noah added. "I remember a few years ago, I came here to watch Ariana Grande and I was just starting to write my music, and I was like, 'It's gonna take me forever to be able to play the Forum,' and I put my single out in November. So for me to be able to go ahead and play the Forum after one single being out is super amazing and I feel super blessed to be here."