Prince William and Kate Middleton became parents of an 8 lb. 6 ounce baby boy late Monday afternoon.
Both mother and child were reported doing well and will remain in the hospital overnight.
Prince William was present for the birth at 4:24 p.m., according to a press release from the royal household.
The release also said the name of the baby, the couple’s first, would be announced “in due course.”
The baby will be third in line to the throne after his grandfather, Prince Charles, and his father.
Crowds massed outside Buckingham Palace where a formal announcement of the baby’s birth was posted to cheers Monday night.
The Duke and Duchess of Cambridge arrived at St. Mary’s Hospital – where William and his brother Harry also were born – early Monday morning.
It was not immediately clear how long labor lasted or whether the child was delivered by natural birth or caesarian section.
Representatives of the world's press had been gathered for days outside of St. Mary's Hospital. The Duchess' exact due date had been a closely guarded secret, but the general sense was that the royal baby's arrival was overdue by at least one or two days.
Despite a rough start to the pregnancy, when she was hospitalized for acute morning sickness, the 31-year-old Kate made a number of public appearances that were halted only near the end of her term.