Chris Pratt has a golden heart!

The 35-year-old actor paid a visit to Children's Hospital Los Angeles Wednesday, Aug. 20, for a screening of his blockbuster film "The Guardians of the Galaxy," which he, along with Marvel and Children's Miracle Network Hospital, arranged especially for the patients, their families and staff of the hospital, E! News reported.

While the movie played, Pratt snuck out of the room and dressed up as his character, Star-Lord. He spent more than three hours in full costume and gave out movie-themed toys to patients. The father of one also visited kids in the Bone Marrow Transplant Unit, the Children's Center for Cancer and Blood Diseases and the Pediatric ICU, as they were too sick to be part of the afternoon movie screening.

Just when the screening ended, Pratt, still in his Star-Lord costume, re-entered the room and posed for hundreds of photos with the kids. He signed autographs for everyone and even generously let several patients to try on his costume.

In a photo posted by Children's Hospital Los Angeles on Twitter, a boy is seen wearing the superhero's leather jacket as the "Parks and Recreation" star looks on with a grin. "Star Lord (@prattprattpratt) cheered up our patients by sharing #GuardiansOfTheGalaxy! Thanks for making them smile!" the hospital captioned the heartwarming photo.

During his visit, Pratt spent some extra time with a patient named Dylan Prunty, a hardcore Lego fan who is being treated for mitochondrial disease. Being a big Lego fan that he is, Prunty recognized that it was Pratt who voiced Emmet, the main character in "The Lego Movie." The two spent about 10 minutes reciting different scenes from the film, according to E! News.

As to why he loves playing with Legos, Prunty previously told CBS Los Angeles that "it distracts the pain. It's like the best pain medicine."

Before "The Guardians of the Galaxy" became a huge hit, Pratt revealed that he had taken his Star-Lord costume so he could visit and cheer up sick children.

"I stole the jacket and some of the wardrobe so that, if this movie comes out and does what everyone hopes it can, I can follow the example of someone - say, like, a (Seattle Seahawks quarterback) Russell Wilson - and go visit kids," he told Panzer TV last month.

"If it was a big enough movie to where it would mean something to a kid who's sick in the hospital for Peter Quill or Star-Lord to come visit them, I'll do that," he added. "That would give me real meaning for this movie, you know?"

"The coolest things would be that my son can one day see this, and that maybe I can go affect some kids in a positive way, (and) be a good role model for them," he said.

As of Aug. 20, "The Guardians of the Galaxy" has grossed $231.6 million in the US and $196.4 in international markets, according to Box Office Mojo.