The actor is said to have teamed up with Marvel and the hospital to organize the screening for patients, families and staff.
After the show, Pratt, 35, changed into a Star-Lord costume -- his character in the film -- and spent about three hours handing out toys from the movie, playing with children and signing autographs.
The Parks and Recreation star also incarnated his character from The Lego Movie while spending time with patient Dylan "Lego Kid" Prunty, whose Make-A-Wish dream was to get a Lego replica of the hospital.
Pratt is set to reprise his role as Peter Quill in the upcoming sequel of Guardian of The Galaxy.
Notable deaths of 2014 [PHOTOS]