The 34-year-old singer-actor headed to Great Ormond Street Hospital to meet patients at the facility and took to his micro-blogging site Twitter to document the trip, reported Daily Express.
"Such an incredible time at Great Ormond St Children's Hospital. Such brave kids!," he posted.
He also uploaded a photo posing with a female patient.
"Had the pleasure of meeting Rebecca today with Matt at our great ormond st children's hospital visit. Sending more love Bec," he addded.