Members of the public were packed into the council meeting this afternoon where the motion was passed 7-4 as part of the council's consideration of its Draft Climate Action Plan.
Extinction Rebellion said in a statement last week it was "asking the council to use its role as a community leader to clearly communicate the reality of what we are facing and what needs to happen to our local community."
Several councils in New Zealand have already made similar declarations, including the Dunedin City Council which declared a climate emergency on Tuesday.
The group staged its first action - erecting a banner in front of a landmark tree in Lake Wanaka - in April.
It is part of the international Extinction Rebellion movement, founded last year in the United Kingdom, which made headlines for large protests in London.
The QLDC also narrowly voted 6-5 to receive Queenstown Airport Corporation's controversial Statement of Intent (SOI), while inserting a clause requiring ongoing discussions over possible expansion.
Several councillors expressed their dissatisfaction with the SOI.