They also posed for a few photos, as seen below.
"Never naughty, always nice," one caption read. "The kids at CHLA received a much-deserved visit from Santa and Mrs. Claus ... who happen to look a lot like Katy Perry and Orlando Bloom!"
Earlier this year, Perry, 32, performed at a benefit for the hospital, the Los Angeles Times reported, and while on stage, she gushed about her emotional connection to its young patients.
“Children are vulnerable," she said. "We have a responsibility.”