Record numbers of people attended Anzac dawn services in some centres, as tens of thousands of people took part in commemorations around New Zealand.
It is 95 years since the Australian and New Zealand Army Corps landed at Gallipoli, in Turkey, on 25 April 1915.
More than 2700 New Zealand troops died during the eight-month campaign.
Prime Minister John Key is in Gallipoli for the commemorations there.
Mr Key said Anzac Day was an occasion to recognise serving defence personnel as well as the sacrifice of those who had died in war.
Auckland commemorations began with a dawn service at the Cenotaph Court of Honour in front of the War Memorial Museum.
Police estimated up to 15,000 people were gathered, including a large number of young people.
Many families who attended the service, said they felt it is important for their children to remember history and the sacrifices made for the next generation.
In the capital, an estimated 3000 people attended the dawn service at the Cenotaph in Wellington.
A single cannon shot heralded the beginning of the ceremony.
A Citizen's Service of Commemoration was held at St Paul's Cathedral in Thorndon later in the day.
Personnel from the armed forces observed a dawn to dusk vigil at the Tomb of the Unknown Warrior.
In Christchurch, a march left at 6.15am from the Heritage Hotel heading to the Cenotaph in Cathedral Square.
Dunedin also remembered its fallen at a dawn ceremony at the Cenotaph in Queens Gardens with about 6000 joining in the commemorations.
The Returned and Services Assocation chief executive Stephen Clarke said there has been a resurgence of people attending services to pay their respects.
More than 1000 people attended a service at the cenotaph in Anzac Park, Nelson.
Veterans from World War II and the Korean War, and the Malaya and Vietnam campaigns took part.
Attendance at the Cenotaph in New Plymouth was noticeably larger than last year - about 2000 people.
New Plymouth RSA immediate-past president Graeme Lowe said the numbers had been boosted by better education about New Zealand's war history and Anzac Day coverage by Maori Television.
The community of Portobello in Dunedin has held its first Anzac service in more than 50 years.
About 150 people attended the service at the Portobello museum, where a sandstone monument honouring seven Portobello men who died in World War II, was unveiled. All are buried overseas.
Another plaque is to be added to the memorial, honouring Portobello servicemen who died in World War I.
Dozens of New Zealand volunteers at Gallipolli helped to distribute information and help people with disabilities.
One of them is Hilda Davidson of Auckland, who is following in the footsteps of two great uncles who joined the Auckland Mounted Rifles and died at Gallipoli on the same day.
She says it is a very moving experience to be part of the commemorations which left a mark on so many families.
Flags signify Anzac spirit
The Australian national flag flew alongside New Zealand's on the Auckland harbour bridge on Sunday for the first time.
Two New Zealand flags fly on the bridge every day of the year and the only other exception is Waitangi Day when the Maori flag flies alongside them.
Transport Minister Steven Joyce says having the Australian and New Zealand flags flying together on Sunday is a fitting tribute to the special relationship between the two countries born of the Anzac spirit.