On 15 March 2019, Australian white supremacist Brenton Tarrant opened fire at Al Noor Mosque and Linwood Islamic Centre as the congregations marked Jumu'ah - the most significant prayer of the week.
This year's commemorations started with a walk-the-talk-for-unity event at the Bridge of Remembrance, organised by the Sakinah Community Trust, an organisation established by a number of the widows.
A service at the Peace Bell in the botanic gardens started with a minute's silence, followed by the names of the 51 victims.
It will conclude with the laying of wreaths.
'Showed the world strength, compassion and unity' - PM
In a post on social media, Prime Minister Christopher Luxon paid tribute to those who lost their lives.
"Today we remember the 51 people who were killed in the Christchurch attacks, and we think of the families, friends, and communities who still live with that loss.
"Seven years ago, Christchurch, and New Zealand, showed the world strength, compassion and unity in the face of tragedy.
"We honour those who were taken from us by continuing to build a country where everyone can live in peace and safety," the post said.
