Prince George will accompany the Duke and Duchess of Cambridge on their visit to New Zealand and Australia next April, Kensington Palace has confirmed.
At the time of his first official overseas tour the baby prince will be eight months old.
Details of the itinerary have also been revealed - including visits to Uluru, in Australia's Northern Territory and Christchurch in New Zealand.
The entourage of 11 people will include a nanny and a hairdresser.
The royal party will travel to Australia on a scheduled flight, arriving on Monday 7 April.
The three-week trip will echo the Prince and Princess of Wales's visit to Australia and New Zealand in 1983 when the couple took William, then aged nine months, with them.
Then, the princess's wardrobe was said to have weighed three tonnes and one million people were reported to have turned out to see them.
Three decades on, royal watchers will have to content themselves with limited glimpses of Prince George - such is his age and the protectiveness of his parents, says BBC royal correspondent Peter Hunt.
According to William's most senior official, there is no hiding the couple's enthusiasm for this visit, our correspondent added.
The tour will begin in Wellington - where the royal couple will be greeted with a ceremonial welcome to New Zealand, called a Powhiri in Maori. Their time in New Zealand will also include a yacht race and visits to a Maori tribe, a rugby stadium and a vineyard.
In Australia, there will be visits to destinations including Sydney, the Blue Mountains, Queensland, Adelaide and Canberra.
While the duchess is yet to pay an official visit to either country, she and her husband were in the media spotlight when they flew to Brisbane airport to catch a flight home at the end of their South Pacific tour in September 2012.
Prince William's last official trip to New Zealand and Australia took place in March 2011, when he was in Christchurch, shortly after it suffered an earthquake, and in Queensland and Victoria, which had been hit by floods.
In January 2010 he represented the Queen at the opening of the Supreme Court building in the New Zealand capital Wellington and also visited Auckland, and during the same trip travelled to Melbourne and Sydney.
The duke and duchess made their first overseas visit together shortly after their wedding when they were in Canada and the US in July 2011.
Their only other trip abroad was the nine-day visit in September 2012, which saw them in South East Asia and the South Pacific as part of the Queen's Diamond Jubilee celebrations.