And just before the panel, Delevingne stepped out rocking a cute shoulder-length cut.
ET's Ashley Crossan got a chance to catch up with the actress and Valerian co-star Dane DeHaan pre-panel, where they dished on her new look.
"I did it," DeHaan joked, after Delevingne revealed she went for the big chop this morning.
"I cut his hair too. We do each other's," she added.
And while the Paper Towns star cut a few inches off, she knows it's not enough to roam around the convention floor undetected. "[I'll be] wearing a Where's Waldo outfit," she confessed. "That's what I'm going to wear."
Valerian and the City of a Thousand Planets is set to release July 17, 2017.