Amid tight security, Prime Minister Jacinda Ardern will join mourners near the Al-Noor mosque, one of the two places of worship targeted in last Friday's shootings.
Later a mass burial will take place for many of the victims.
Fifty people were killed and dozens more wounded in the attacks.
Australian Brenton Tarrant, a self-proclaimed white supremacist, has been charged with one murder and is expected to face further charges.
On Thursday Ms Ardern announced a ban on all types of semi-automatic weapons.