The song came one day after both Kelly and Miley took the stage on Thursday at the "VH1: Divas" concert.
"I don't even know my own lyrics so don't be offended," Kelly joked, singing the song while reading the lyrics on her smartphone.
The three singers harmonized together in the intimate performance while one strummed an acoustic guitar.
CLICK HERE to see the performance!
Related Content from AccessHollywood.com:
VIEW THE PHOTOS: Since She's Been Gone: Catching Up With Kelly Clarkson
PLAY IT NOW: Former 'Idols' Shine At 2009 'VH1 Divas' Concert
PLAY IT NOW: Kelly Clarkson's Free Hollywood Concert