Ardern used her speech to outline what a Labour-led Government would do in its first 100 days.
At the top of the checklist were warmer, drier homes, support for families and students, and new inquiries into systemic and historical issues.
Foreign, non-resident homebuyers would be shut out of the housing market by Christmas through an urgent law change - a move which National says will breach New Zealand's free trade agreements.
Another urgent law change would introduce higher minimum standards for heating and insulating rental properties.
Labour plans to scrap National's tax cuts but says its replacement, a families package, will come into force within the 100-day period. It would extend paid parental leave to 26 weeks, provide $60 a week to families with children under 1 and give the elderly or beneficiaries $140 a week for power bills during winter.
Tertiary education would become free as of January 1, and student allowances and living costs would jump by $50.
Ardern said a Labour-led Government would get two major inquiries under way in its first 100 days - one into the mental health system, and another on the abuse of children in state care.
There were also a series of promises on environmental measures, the minimum wage, and superannuation payments.
In response, National's campaign chair Steven Joyce accused Ardern of "hiding Labour's real plan".
There was no mention of Labour's tax working group or any reference to the plan to scrap National's tax cuts, he said.
The Labour rally contrasted to Ardern's appearance at a suicide prevention rally outside the Beehive an hour earlier.
She stepped up to give a speech and immediately began crying when she saw 606 pairs of shoes lined up on Parliament's front lawn, placed there to represent New Zealand's suicides in the last year.
"Those shoes are quite moving," she said. "The idea that we have lost 600 New Zealanders in the last year I find absolutely devastating."
Ardern said the issue had personal significance because of the death of her best friend's brother to suicide when she was 13.
Before she spoke, several families had given harrowing personal stories.
Haley Grace-Hollis, from Ruatoria, spoke about losing two brothers and two sisters to suicide in nine years.
"Yes, you heard right. Two brothers, two sisters, to suicide," she said.
"I'm here today to stand on behalf of them and on behalf of the family we have still standing here today.
"It's been a hard journey, we never got help. We didn't even know what services were there to help us."
Ardern said a Labour Government would focus on students by putting mental health teams in every state secondary school.
She said Labour's target for New Zealand's suicide rates would be zero: "Because anything else suggests we have a tolerance for loss to suicide in New Zealand."
