Michelle Obama Sings with Bruce Springsteen On Stage During Concert in Barcelona

Add Bruce Springsteen backup singer to Michelle Obama's list of milestones completed ... cuz she just hit the stage with The Boss overseas during one of his shows.

Check out the video, taken Friday night at Bruce's concert in Barcelona. You see Michelle and actress Kate Capshaw join Bruce's bandmate, Patti Scialfa, behind the mic to sing background on Springsteen's hit "Glory Days."

Michelle is all smiles as she belts out the tune, even jamming with a tambourine.

No sign of her hubby, former President Barack Obama, but you gotta imagine he and Kate's husband, Steven Spielberg, were watching in the wings.

As we reported ... Bruce, Barack, Michelle, Steven and Kate all grabbed dinner together in Barcelona Thursday night -- a day before the big show.

Patti appears to have been at the dinner as well, so it's possible they planned the special guest appearance over some good grub.