Environment groups say the declaration of a climate emergency could be an important turning point.
Ireland has become just the second country in the world to do so after the UK.
The government and opposition parties accepted a Fianna Fáil amendment to an all-party climate change report last night.
It comes as EU leaders put action on climate change at the top of the agenda in the next five years.
Climate Action Minister Richard Bruton said climate change has been “rightly” described as the greatest challenge facing humanity.
Cliona Sharkey from the Stop Climate Chaos group says that report now needs to be acted on.
"That's the clear message that the Dáil is sending to the Government: if you're serious about declaring an emergency, if you're serious about action then you need to integrate this plan and all of its 41 recommendations into the Government plan and ensure that it is implemented in full and on time," she said.
This is not just symbolic, it's very substantive and could be an incredibly important turning point.
Climate change campaigner Greta Thunberg, 16, who has led a movement of young people across Europe calling on leaders to take action, welcomed the declaration.