He confirmed he had not seen the due diligence report and risk review, but had been fully briefed by Ateed chief executive Phil O'Riley and had confidence the board had undertaken all the proper work to protect ratepayers and ensure a successful event.
Councillors had had two briefings before Thursday's vote on the matter, he said.
Mr Brown said the event would be "massive for Auckland" with 50,000 visitors and an economic benefit at the "very least" of $8 million to $10 million a year from an investment of $2.1 million.
He rejected a call by Cameron Brewer for an extraordinary meeting on his return to allow councillors, council staff and the public to view and assess the reports, albeit behind closed doors for commercially sensitive information.
Last night, Mr Brewer said the mayor was not interested in transparency and accountability and accused Ateed of controlling the flow of information.
Ateed later said the figure of 50,000 nights came from a economic impact report by Covec. It used figures from the 2011 event in Hamilton, statistics from other events, interviews with V8 Supercars and conservative assumptions.
A spokesman said of the 50,064 visitors nights, about half would stay with friends and relatives.
The Auditor-General is investigating a complaint from councillor Cathy Casey on whether the council should have had access to confidential information and whether withholding it compromised last Thursday's decision.