A smiling Kate, wearing a baby blue polka dot dress, carried the future monarch outside St Mary's Hospital in central London so that he could be photographed by the dozens of international press members waiting outside.
The photos are likely to be reprinted for decades as the baby grows into adulthood and his role as a future king. His name has not yet been announced; that's expected in the next few days.
Kate, who said she felt "very emotional,'' passed the baby to her husband, who appeared relaxed and joked with reporters. "He's got her looks, thankfully,'' William said. "He's got a good pair of lungs on him, that's for sure.''
William added: "He's a big boy, he's quite heavy,'' and laughed when a reporter asked him about the baby's hair. "He's got way more than me, thank God,'' he said.
The couple re-entered the hospital to place the child in a car seat before re-emerging to get into an SUV. William drove the couple away ' palace officials said they will head to an apartment in Kensington Palace from the hospital.
The young family's first public appearance together has been the moment that the world's media and crowds of onlookers camped outside the hospital had long been waiting for. It recalls a similar appearance three decades ago, when Princess Diana and Prince Charles carried the newborn William out to pose for photographs on the same steps in 1982.