The royal couple laid a wreath at the cairn, in the Auckland suburb of Mount Roskill, which was renovated in 2015 for the Centenary of the First World War.
Charles appeared moved during the event as he stood next to a solemn faced Camilla.
In 2016, a memorial was built to recognise men from Niue, an island in the Pacific, who fought with a Maori contingent during World War 1.
Charles and Camilla’s tour came as his brother The Duke of York faced growing controversy media after a ‘car crash’ BBC interview on his association with convicted paedophile US tycoon Jeffrey Epstein.
Members of the city’s Niue community sung traditional songs from the Pacific Island nation ahead of the royal’s arrival.
The couple later visited the Wesley Community Centre, where they were officially welcomed with a traditional Maori greeting, a hongi.
Male dancers performed for the couple, before they met other users of the centre, located in a south Auckland suburb which has a high proportion of South Pacific Islanders, refugee and migrant families.
Charles met Richard Barter who runs Bike Kitchen, which repairs donated bikes and gives them to local families.
Charles was particularly taken with his Shih Tzu Chino who had been given a bath ‘specially for the royal visit’.
Joelle Leilua, five, gave Camilla a golden wreath of Cadbury’s Crunchie bars.
The Prince laughed as he rearranged her garland, which had been made by the Kidzone programme and they had chosen gold to signify the royal couple.
Charles later tried his hand at turning plastic waste into designer furniture.
Rui Peng, co-founder of Auckland recycling firm Critical Design, asked Charles: “You’re good at that, do you want a job?”
The Prince, on the first full day of the royal tour to New Zealand with his wife Camilla, met staff and took took part in the recycling process.
Mr Peng said: “The Prince got quite animated about what we do here. He said he has been advocating this for years, making use of waste plastic is critical for the future.”
It is the couple’s third visit to the country, after travelling in 2012 to mark the Queen’s Diamond Jubilee and again in 2015.
The royals will travel to Christchurch on the country’s South Island to observe the regeneration of the city since the 2011 earthquake, and see how the community has rallied in the aftermath of the March 15 terrorist attacks.
The couple will also visit the northern Bay of Islands region and the southern coastal town of Kaikoura during their visit.
Ahead of the visit, Prime Minister Jacinda Ardern said in a statement: “I know that the couple have greatly enjoyed New Zealanders’ warm hospitality… when they visited previously.
“The Prince of Wales has been a strong advocate for the environment, conservation and sustainability for many years. This visit will provide opportunities for him to engage with New Zealanders on those subjects, and to learn more about the ways in which New Zealand is preparing for the future.”