The Duke and Duchess of Sussex, who have been visiting Europe this week, will attend the glittering ceremony on Thursday.
Harry is expected to commend the courage of the young people recognised, and thank those who care and support them.
The Duke has been patron of WellChild, the national charity for seriously ill children and their families, since 2007.
It comes after Meghan and Harry reportedly borrowed a £43million German taxpayer-owned Luftwaffe jet to take them to and from Dusseldorf on Tuesday.
The German Air Force plane was a Bombardier Global 5000 usually reserved for senior members of the German government or armed forces.
It landed in the UK on Tuesday morning and took the couple from RAF Northolt at 11.34am, landing at Dusseldorf Airport at 1.23pm - 15 minutes behind schedule, MailOnline reports.
The plane left Dusseldorf at 8.51pm, after the Invictus engagement, landing back at Northolt under an hour later.
On Thursday evening, the couple will meet the winners of each award category – which include health professionals, and members of their families – during a pre-ceremony reception.
Harry will give a speech during the event and the couple will present the award for most inspirational child aged four to six.
The awards celebrate the inspiring qualities of some of the country’s seriously ill young people and the dedication of those who go the extra mile to keep children healthy and happy, including health, social care and education professionals.
On Monday the couple attended the One Young World summit in Manchester where Meghan delivered a keynote speech and declared it was “very nice to be back in the UK” and told the young leaders “you are the future, you are the present”.
It was their first public appearance in the UK since they joined other members of the Royal Family for events in June that celebrated the Queen’s Platinum Jubilee.
Meghan Markle and Prince Harry MOLLY DARLINGTON
The Duke and Duchess of Sussex in Manchester MOLLY DARLINGTON