The two musicians hit the stage to perform "Really Don't Care" off Lovato's Demi album.
Afterward, Lovato accepted the first surfboard of the night for choice song of the summer.
"Thank you guys so much, this is amazing, and I dedicate this not only to my fans, also Cher Lloyd because we did this song together and she's amazing," she told the Shrine Auditorium audience. "Instead of just getting up here and saying a speech, each one of you deserves to live a happy and healthy, incredible life."
Watch the performance below:
This article originally appeared on The Hollywood Reporter.