The singer/actor headed to Great Ormond Street Hospital to meet patients at the facility and took to his Twitter.com page to document the trip.
In a post, he writes, "Such an incredible time at Great Ormond St Children's Hospital. Such brave kids!"
Actor/model Colton Haynes accompanied Morrison on the trip, and he has uploaded a photo to Instagram.com of the pair posing with a female patient.
He adds, "Had the pleasure of mtg (meeting) Rebecca today with Matt at our great ormond st children's hospital visit. Sending more love Bec."