Despite Ardern's call, National and Act opposed the motion - National's climate change spokesman Stuart Smith said it was "virtue signalling".
But Ardern said the declaration was an "acknowledgment of the next generation", she said.
"It is up to us to make sure we demonstrate a plan for action, and a reason for hope."
She said it's not in Kiwis' DNA to turn our backs on a problem. - "we will only make progress if see collective action is required".
Today's decoration acts as a directive to the wider Government – "it acts as a catalyst for change".
The Government's electric vehicle mandate is a lofty goal – there are currently nearly 16,000 vehicles in the Government's fleet.
Today's announcement is the first major post-election commitment by the Government – Ardern said the commitments show the urgency of the situation.
The commitments mean Government agencies will be required to measure, verify and report emissions annually.
They will also need to set gross emissions reduction targets, as well as introducing a plan for how they will reduce emissions.
When it comes to vehicles, Government agencies will be required to "optimise their car fleet" by purchasing electric vehicles or hybrids where EVs are not appropriate for the required use.
That is unless their operational requirements or other circumstances require – such as military vehicles where there is no electric alternatives.
As well as this, Ardern has announced that the Government has begun phasing out coal boilers in its ministries and agencies.
There are roughly 200 coal-fired boilers currently heating water and buildings in the State Sector – the largest and most active will be phased out first.
This, and the purchasing of a greener fleet, will be funded through the previously announced $200 million State Sector Decarbonisation Fund.
Climate Change Minister James Shaw said the 2025 goal shows this Government is taking issues of the world's changing climate seriously.
The implementing of the energy efficiency building rating standard will come into force in January 2026 – that will give the Government time to implement the new mandate.
But, from now on, there will be a requirement to achieve a minimum of 4 stars when establishing new leases and a minimum of 5 stars for new builds.