The rockers headlined the last day of the music event's first weekend (11-13Apr14) and they were introduced by a man wearing a suit made of shattered mirrors, before launching into their hit Reflektor.
The crowd then went wild when frontman Win Butler introduced Harry to the stage to perform Blondie's 1978 classic Heart of Glass.
The veteran star sang with Arcade Fire's Regine Chassagne before providing backing vocals for the band's Sprawl Ii (Mountains Beyond Mountains).
Harry shouted to the crowd: "Cruise on, motherf**kers" as she danced with Chassagne while waving multi-coloured streamers.
After the performance, Harry shared a picture of herself on stage with the group, writing, "Well that was fun Thanks Arcade Fire and Coachella... Blondie 4ever (sic)."