While the kererū population is classed as stable overall, it is in danger of becoming locally extinct in some areas where there has not been sustained predator control, Forest & Bird said.
"The fate of many forests is linked to that of the kererū, as it's the only native bird big enough to swallow and disperse the large fruit of karaka, miro, tawa and taraire."
The kererū's win came despite British comedians Stephen Fry and Bill Bailey backing the rival kākāpō and takahē birds.
Bird of the Year also featured on Tinder for the first time, with Shelly the kakī, or black stilt, attracting 500 matches across New Zealand.
This year's competition was also the most popular with more than 48,000 votes, up from 41,000 in 2017.