The 24-year-old American singer, who is currently on her Honda Civic Tour, is accompanied by Jonas Brothers' youngest Nick Jonas.
Ms Lovato sang a series of her popular numbers, including Neon Lights, Heart Attack and Stone Cold in the final leg of the tour.
In a special message for her fans, she announced, "I think I should do something special for you guys. I want to perform a song that's one of my all-time favourite songs and I've never performed it before so hopefully I can do it justice. Here we go."
Videos from the concert have been shared on social media:
I'm just here to bless your TL with Demi Lovato's phenomenal cover of Adele's "When We Were Young" pic.twitter.com/ydn3yoKjJR? Ronny (@R0NNAYE) September 3, 2016
Followed by the announcement was her rocking performance to Adele's evergreen song.
Post her gig, the Confident singer took to social media and teased fans about some exciting new sounds she may drop sooner rather than later.
This is what she tweeted:
Studio bound... So excited for y'all to hear new music? Demi Lovato (@ddlovato) September 3, 2016
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