Idol was playing at the first night of the iHeartRadio festival at Las Vegas’ T-Mobile Arena when the pop star made the surprise appearance.
According to Rolling Stone, Cyrus walked out onto the stage mid-set, saying she was there to “sing with Billy fucking Idol. Let’s do it!”
The pair then performed the song, during which Idol sang the first verse and Cyrus the second. Watch footage of the performance below.
Cyrus has covered ‘Rebel Yell’ by herself in the past, with the first occasion coming during her appearance at the VH1 Divas gig in 2012.