The Kiwi chart-topper and Grammy Award-winner sent her US-based fans into a frenzy when she announced on social media that she would perform at Pappy & Harriet's, a honky-tonk bar and restaurant in Pioneertown, southern California.
She debuted a new song from her new upcoming album, Melodrama, titled Sober.
The venue has a capacity of just 300 - a world away from the Coachella music festival she is set to perform at on Monday (NZ Time) which will attract 90,000 music fans a day.
But Pappy & Harriet's is a popular trendy haunt - it has hosted the Arctic Monkeys and Rufus Wainwright, and last year music great and former Beatle Sir Paul McCartney played there.
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.
- This article originally appeared in the Herald on Sunday and was republished here with permission.