The Duchess of Cambridge Catherine Middleton gave birth to a boy Monday evening, palace officials said.
The 31-year-old Duchess of Cambridge gave birth to a baby boy this evening at 16:24 (local time), Kensington Palace confirmed.
Prince Cambridge, as the first child of the Duke and Duchess of Cambridge is to be known until being officially named, was born at the private Lindo wing at St Mary's Hospital in Paddington, central London.
The royal couple's first child, who under new laws to succession will remain third in line to the throne, was born with the Duke of Cambridge present beside Kate as she delivered the baby.
She was taken to the hospital in the early hours of this morning by car from the palace to St Mary's.
The couple did not know the sex of their first child, who is third in line to the throne after Prince Charles and Prince William.
The world's press has been camped outside St Mary's for days in anticipation of the birth.
The due date had never been officially announced but had widely been expected to be mid-July.
Royal vehicles were seen at a back entrance to the hospital at about 06:00 am (local time) when Kate was brought to the hospital, with the announcement coming from Kensington Palace 90 minutes later.
The couple travelled to the hospital without a police escort, their spokesman said.
The Duchess was tended by a top medical team led by the Queen's gynaecologist Marcus Setchell, who delivered the Countess of Wessex's two children. Alan Farthing, the Queen's current gynaecologist, assisted in the delivery.
There is a strong police presence around the hospital and two police officers are guarding the entrance to the private wing.
There had been tremendous enthusiasm globally over the birth of the royal baby and the media frenzy outside the hospital has been unprecedented.
Bored journalists had dubbed their vigil outside the hospital as "the Great Kate Wait".
Last week, the Queen joked about the imminent arrival of the newest member of her family, saying she hoped the baby was born before she went on holiday to her private Balmoral estate in Scotland.
Prince William has been with his wife on annual leave and will have two weeks' paternity leave from his job as an RAF search and rescue helicopter pilot.
It is believed the next time the couple will be seen in public is when they appear on the steps of the hospital with their baby.
The Archbishop of Canterbury, who is likely to carry out any christening, had earlier in the day, sent his best wishes to the couple.
"My thoughts and prayers are with Kate and the whole family on this enormously special day," tweeted Reverend Justin Welby.
The new royal baby is the Queen's third great-grandchild.
The couple announced they were expecting their first child in December after the Duchess was admitted to hospital suffering from severe morning sickness.
Since the announcement, the Duchess has carried out 19 days of public engagements before going on maternity leave in the middle of June.
Kate's final public appearance before the birth was at the Trooping the Colour ceremony in June.
The Duke and Duchess of Cambridge were married at Westminster Abbey in April 2011, watched on television by hundreds of millions of people around the world.