Both are longstanding UNICEF ambassadors and are fronting the campaign to protect children around the world from violence, disease, hunger and the effects of war and disaster.
Of the campaign, father-of-four David, 39, said: "If you saw a child in danger, any child you would instantly step up and protect that child from whatever they were facing.
"Millions of children around the world are facing dangers every day – violence, disease and disasters. We need to grab this opportunity to step up and protect them now. Join me in supporting UNICEF's Children in Danger campaign and we can all help keep these children safe."
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Robbie, 40, is father to daughter Theodora and his wife Ayda Field recently welcome their second child.
He said: "I've met children around the world who are facing all kinds of dangers – kids in Haiti who lost everything in the earthquake and little children in Mexico at the risk of violence and abuse.
"Since becoming a dad I realise more than ever how much these children need someone to protect them. With you help UNICEF can keep those children safe, please sign up up to their Children in Danger campaign."
The organisation has released a powerful 90 second clip which shows how the children are facing an epidemic of violence, and other celebrities getting involved include Nicole Scherzinger, Cat Deeley and Emma Bunton.
The public can join UNICEF's Children in Danger campaign and help end violence here.