Lorde announced her own show just six hours before taking to the stage, posting: "$20 tickets because i'm 20 and because i love you. let's get raucous before coachella on Sunday night AHH."
Lorde - who will play music off her upcoming second album both at last night's gig and Coachella - later posted that the tickets had been a quick-fire hit.
After announcing the gig was a sell-out, she added: "Promoter just said under a minute hahahaha i'm dying i love you."
It is not the first time Lorde has delighted fans with a surprise appearance.
The Green Light singer took the stage with producer Jack Antonoff in New York last late year, to raise awareness and money for vulnerable LBGTQ youth, despite not being on the official lineup.
Lorde also surprised audiences in 2016 when she come on stage at Coachella as a guest of Disclosure for one song.
In 2015, Lorde racked up the air miles to make a surprise appearance at her best bud Taylor Swift's concert in 2015, to perform her hit Royals.