George, third in line to the throne of all three countries, follows in the footsteps of his father who travelled Down Under with his parents Prince Charles and Diana in 1983 aged nine months.
The three-week royal tour will be one of the first times the young prince has been seen in public since his birth on July 22 last year.
On March 30 palace officials issued a photo of the chubby prince, wearing a sweater with his name on it, alongside his parents and their dog Lupo in the window of Kensington Palace in London.
The symbolism of the trip is clear, with George also being directly in line to become king of Australia and New Zealand after grandfather Charles and then William.
George will only be taken to a few engagements throughout the trip, Kensington Palace said.
In New Zealand, the royal couple will start their visit in Wellington on Monday with a ceremonial welcome including a Maori dance, and inspect a guard of honour.
George could have some playmates on Wednesday when William and Kate attend a reception at Government House in Wellington with new mothers and their toddlers.
On Thursday they travel to Blenheim for a wreath laying session honouring New Zealand soldiers killed in World War I, which broke out 100 years ago.
They will also meet Prime Minister John Key and attend a state reception where William will unveil a portrait of Queen Elizabeth II.
The couple are in Auckland on Friday, Hamilton and Cambridge on Saturday, Dunedin and Queenstown on Sunday, where they will brave the Shotover Jet -- a high-speed white-water thrill ride down a river canyon, and Christchurch on April 14, where they will pay their respects to victims of the 2011 earthquake.
- Nanny and hairdresser on tour -
Australia hosts the couple from April 16 when they arrive in Sydney, before travelling on to the Blue Mountains on April 17, Brisbane on April 19, Uluru (Ayers Rock) on April 22, Adelaide on April 23 and Canberra on April 24 and 25, before flying home.
Specific events on the tour will celebrate Australia's and New Zealand's achievements in the fields of technology, tourism, sports and the creative arts.
Their 11-person entourage will include a hairdresser and a recently-appointed Spanish nanny. They fly to and from London on scheduled flights.
William's private secretary Miguel Head told reporters in March that the couple had put in a lot of planning for the visit, which will be Kate's first to either country.
"Taking a nine-month-old on a royal tour is not a first," but has not happened for a long time, said Head.
"So there has been much to think about -- as any new parent travelling long distance will recognise."
William and Kate were treated like celebrities when they visited Canada months after their wedding in 2011, while in 2012 they toured Singapore, Malaysia, the Solomon Islands and Tuvalu on behalf of Queen Elizabeth to mark her 60 years on the throne.