Pharrell Williams just made a little kid's dream come true by getting him a ride to his concert and serenading him with "Happy" onstage.

Eight-year-old Reef Carneson suffers from acute lymphoblastic leukemia and has been in the hospital since he turned one. He's a huge Pharrell fan and dreamed of meeting him someday.

Enter celebrity weed mogul turned cancer advocate Milk Tyson, who made a video last Wednesday with Reef asking Pharrell for a FaceTime session.

Once Pharrell got word, he invited Reef to his Saturday night show in Philadelphia. However, Reef's immune system is too weak for air travel, so Pharrell hired a private car to drive him all the way from Cincinnati.

Milk says the singer put them up in a 5-star hotel, got them tickets and backstage passes. Best of all, Reef and his sister got onstage with him for "Happy."  Keep in mind, Pharrell hopped a plane the next day to perform at One Love Manchester.

That's a big-hearted weekend.