Christchurch Airport and the New Brighton Pier will be lit up to mark the arrival of the royal baby.
Officials announced that the Duchess of Cambridge, Kate Middleton, safely delivered a son, weighing 3.8 kilograms (8lbs 6oz), at 3.24am today (NZ time).
New Zealand's official gift to the duchess and Prince William is a hand-spun, hand-knitted fine-lace shawl, similar to the one that New Zealand gave when William was born.
The shawl was designed by Lyttelton's Margaret Stove, who was also responsible for William's shawl.
Cynthia Read spun the wool and knitted the shawl.
Stove said the pattern for the shawl had been picked by Creative Fibre, the New Zealand Spinning, Weaving and Woolcrafts Society, from her latest book, Wrapped in Lace.
The pattern was called Filmy Fern, and it depicted a New Zealand fern.
"I designed and spun the shawl for Prince William, so it's quite nice to contribute something to this baby too. I think it's a nice gift for him."
Stove was taught to knit as a 4-year-old by her grandmother and has been a compulsive knitter ever since.
She was given a kitset spinning wheel while living in Arthur's Pass in 1970 and began spinning merino wool, creating super-fine lace-weight yarn, as well as hand-spun silk.
Now in her mid-70s, she still teaches knitting to others and has several books on the craft. More information about her art can be found on her website.
Monarchy New Zealand Christchurch co-ordinator Alex Summerlee said the birth was "very significant" for New Zealand and, in particular, Christchurch.
"For New Zealand, this is huge news because it is the birth of the ... future monarch. It is very important," he said.
"Christchurch, in particular, shares a close bond with Prince William after he visited here after the earthquakes, so I think there will be a lot of excited Cantabrians today.
''It also means the region can look forward to the new prince and his parents hopefully visiting Christchurch again in the future."
Cantabrians who wanted to congratulate the couple were being encouraged to donate to the Royal New Zealand Plunket Society.
"This is an organisation Prince William and the Duchess of Cambridge fully support, and donating also benefits many children," Summerlee said.
Prime Minister John Key said: "The birth of a child is a time of great joy and excitement, and I know they will make excellent parents."
ROYAL FAMILY 'DELIGHTED'
The Duke of Cambridge, Prince William, was at St Mary's Hospital for the birth.
The son is the first child born to the royal couple, who married on April 29, 2011, and is third in line for the throne, after his father and his grandfather, Prince Charles.
The Queen, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall, Prince Harry and members of both families had been informed and were delighted with the news, officials said.
"Her Royal Highness and her child are both doing well and will remain in hospital overnight."
Prince Charles said in a statement: "Both my wife and I are overjoyed at the arrival of my first grandchild. It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy.
"Grandparenthood is a unique moment in anyone's life, as countless kind people have told me in recent months, so I am enormously proud and happy to be a grandfather for the first time and we are eagerly looking forward to seeing the baby in the near future."
KIWI BABIES SHARE JOY
The birthdate of the future king is likely to be shared by about 167 New Zealand babies, Statistics New Zealand says.
"Baby boys born today in New Zealand might expect to live 90 years on average and girls 93 years," statistician Dallas Welch said.
If heredity is anything to go by, the royal baby has a good chance of living even longer than that. The Queen, the new prince's great-grandmother, is 87, and the Queen's mother lived to 102.
"As third in line to the throne, the new prince may have a long wait until he becomes king," Welch said.
The new prince is likely to see plenty of change over his lifetime and be part of many milestones.
"During her reign, the Queen has seen 14 New Zealand prime ministers take office, the dollar replace the pound in New Zealand and the All Blacks win the Rugby World Cup twice," Welch said.
When Prince William was born in 1982, the New Zealand population was 3.2 million.
Today, the population is nearing 4.5 million, and in another 30 years, when the new prince may be having his first child, Statistics New Zealand projects that the population could be about 5.6 million.
OTHER FAMOUS PEOPLE BORN ON JULY 22:
George Mendel, botanist, was born in 1822.
Rose Kennedy, matriarch of the Kennedy clan, was born in 1890.
Oscar de la Renta, fashion designer, was born in 1932.
Danny Glover, actor, was born in 1946.
Don Henley, musician from the Eagles, was born in 1947.
David Spade, actor, was born in 1964.
Rufus Wainwright, singer and songwriter, was born in 1973.
Selena Gomez, singer and actress, was born in 1992.
LANDMARKS TO BE LIT UP
Advocacy group Monarchy New Zealand said more than 37 landmarks across New Zealand would be illuminated tonight to celebrate the birth.
Participating landmarks include Auckland's Sky Tower, Dunedin's Larnach Castle, Gisborne's Town Clock, Blenheim's War Memorial and Oamaru's Opera House.
Monarchy New Zealand chairman Sean Palmer congratulated the royal couple on the birth of their son.
"This is the first time in over a century that a monarch of New Zealand has lived to see three direct heirs. It is a great moment in the continuity of Aotearoa's constitution," he said.
Christ Church Cathedral (Nelson).
War Memorial Clock Tower (Blenheim).
Amuri Ave (Hanmer Springs).
New Brighton Pier (Christchurch).
Opera House (Oamaru).
Town Hall (Dunedin).
Toitu Otago Settlers Museum (Dunedin).
Wall St Mall (Dunedin).
Larnach Castle (Dunedin).
Otago Boys' High School (Dunedin).
Southland Museum and Art Gallery (Invercargill).
The Duke of Marlborough Hotel (Russell).
Old Town Hall (Whangarei).
Victoria Canopy Bridge (Whangarei).
Sky Tower (Auckland).
The Cloud (Auckland).
Holy Trinity Cathedral (Auckland).
Victoria Bridge (Hamilton).
Clock Tower in Jubilee Gardens (Cambridge).
Town Hall (Cambridge).
i-Site Dog (Tirau).
Clock Tower (Te Aroha).
Princes Gates (Rotorua).
Tairawhiti Guardian Sculpture (Gisborne).
Town Clock (Gisborne).
Great Lakes Centre (Taupo).
Clock Tower or Puke Ariki (New Plymouth).
Gilray Fountain (Napier).
Royal Wanganui Opera House (Wanganui).
Albatross Fountain (Wellington).
Regent on Broadway (Palmerston North).
Clock Tower (Palmerston North).
Wairarapa Times Age Building (Masterton).
The Majestic Centre lights (Wellington).
Digital Wall, Wellington Airport.
Michael Fowler Centre (Wellington).
For a Google map of landmarks to be illuminated please see: http://goo.gl/maps/GzXOh
- © Fairfax NZ News
Why are fewer teens learning to drive?Related story: Teen non-drivers lazy 'narcissists'