He said the scandal greatly affected his public image.
"I think it certainly had an impact on the view of Aucklanders towards me."
Mr Brown said that after talking with his wife Shan and three daughters, he decided nine years as mayor, including for Manukau, were enough.
Labour MP Phil Goff, who is declaring his candidacy for the mayoralty on November 22, said Mr Brown had worked hard to settle the structures of the new city.
"The mayor also has so much passion for the City Rail Link, which I also endorse, and that will be part of his legacy."
Former Auckland City Mayor John Banks, who stood against Mr Brown at the first Super City elections in 2010, has not ruled out standing again next year.
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Mr Banks, 68, said in the absence of a younger, more energetic candidate, there was a possibility he could stand.
Of Mr Brown, he said: "His leadership was, at least, quirky but irrelevant and, probably at worst, missing in action."
Deputy Mayor Penny Hulse said she was standing again but her focus was on getting the region's new rule book for growth, the Unitary Plan, into shape for council to approve in July or August.
Councillors told the Herald they were annoyed by getting word of Mr Brown's decision at 9am on Sunday - when a news release was sent out by the mayoral office.
This was described as "typical" of Mr Brown's aloof leadership style by Penny Webster, who is the chair of the finance and performance committee.
"We've been telling him for months to put us all out of our misery so we can move on."
However, councillor Linda Cooper feared party politics and populist causes would get in the way of building public confidence in the council. NZME