Incumbent Wellington mayor Kerry Prendergast will have a nervous two-day wait to see if she holds her position in the capital.
Ms Prendergast tonight held a wafer-thin 40 vote margin over candidate Celia Wade-Brown.
Special votes will not be finally counted until Monday.
Newcomer Jack Yan came third in the race in front of Bryan Pepperell.
After the announcement was made tonight at the Wellington council chambers, Ms Prendergast told reporters that holding onto a fourth term was always going to be difficult.
"It was a hard race fought by Celia, so we always knew it was going to be close."
She confirmed that if she does win the mayoralty, it would definitely be her last term in office.
"I have no doubts that the work that's happening in the region about what will be the future for governments in this region will herald changes, and I think it needs someone new and fresh to take forward the city once that happens."
Ms Prendergast said she was opposed to the area following Auckland's lead in becoming a so-called super city.
"I don't think the problems that Auckland had are replicated here, but it's clear that we can't stay the same.
There will need to be some changes, but it's a long continuum between status quo and what's happened in Auckland.
Meanwhile Nick Leggett has become's Porirua's new mayor after Jenny Brash stood down from the role.
Lower Hutt's mayor David Ogden has been soundly beaten by Wainuiomata ward councillor Ray Wallace after a tough campaign.
Mr Wallace received 15,569 votes compared to Mr Ogden who won 10,624.
Wayne Guppy has kept his position as mayor in Upper Hutt.