The pop star was due to perform at Spark Arena on February 1.
But in an Instagram post, she said the date was being moved to October so she could embark on a "much bigger" world tour.
Carey will now play the same venue on October 7. Refunds are available for those that can't make the new date.
"It's always unfortunate when these situations occur and we regret any inconvenience the rescheduling has caused for fans," said promoter Scott Mesiti.
"We're very excited that we've been able to find suitable time for Mariah's return to ensure fans don't miss out on what is sure to be a spectacular show from one of the music world's biggest music icons."
Carey's one of many pop stars due to visit New Zealand next year, including Ed Sheeran, Bruno Mars, Taylor Swift, Pink and Katy Perry.
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"Lambs"? Young lady, do you think us the offspring of ruminants?
The promoter should be ashamed. Take the gig, do the gig. You are a Star, so change is expected. Can they not organise?