In a Sally-inspired costume, the “Happier Than Ever” singer — whose album of the same name topped the Billboard 200 chart in August — performed the character’s solo “Sally’s Song,” and she joined in to briefly sing Sally’s “Simply Meant to Be” verse as well.
“peeing my pants i’m so excited,” Eilish wrote on Instagram ahead of the concert.
The concert event featured a full orchestra led by conductor John Mauceri to perform the film’s score and songs live.
Elfman reprised his role of Jack Skellington, King of the Pumpkin Patch, for the show, which is also scheduled for a second night at L.A.’s Banc of California Stadium on Oct. 31.
Watch Eilish’s Friday night performance below.