Lawrence posed for photos with the children at the hospital, as well as several staff members.
"A very special visitor stopped by our Canada hospital today," Shriners wrote on their official Facebook page. "Jennifer Lawrence is in Montreal filming a new movie and she made time to visit some of our #ShrinersCanada kids and staff. Everyone had a great time!"
In one photo, Lawrence signed a little boy's red cast, while in another, she crouched down next to a boy using a walker.
"You never know who might visit @ShrinersCanada," the hospital also Tweeted, sharing more photos of Lawrence with patients.
The actress returned to Montreal after vacationing with Amy Schumer and her friends in the Hamptons two weeks ago.
"She's the coolest chick you'll ever meet," Schumer said of Lawrence when she stopped by The Daily Show with Jon Stewart last week.