The Duke of Sussex said he had a newfound appreciation for the sick children's charity WellChild after becoming a parent.

Britain's Prince Harry welled up while delivering an emotional speech on Tuesday at an annual awards ceremony for children with severe illnesses, their families and caregivers.

Harry, 35, who first attended the WellChild Awards more than a decade ago, recounted how his feelings about the event changed while attending the last year's ceremony knowing his wife Meghan was pregnant.

"I remember squeezing Meghan's hand so tight during the award and both of us thinking, 'what it would be like to be parents one day' and more so 'what it would be like to do everything we could to protect and help our child should they be born with immediate challenges or become unwell over the time'," he said after being overcome with emotion and earning applause from the crowd.

The Duke and Duchess of Sussex became parents for the first time with the birth of their son, Archie, in May. Harry said becoming a father deepened his appreciation for the charity's work in supporting sick children.

"As parents, being here and speaking to all of you pulls at my heartstrings in a way I could never have understood until I had a child of my own," he said.

Harry applauded the families at the award ceremony, saying their example was a greater source of optimism, hope and strength that no amount of parenting advice could ever give.