Auckland Council is paying $60.7 million for Auckland University's home for cricket and rugby.
Colin Maiden Park in St Johns adds 20ha to the public's sporting fields portfolio.
In March, the Herald reported the university was giving the council first option to buy as it planned to quit its Tamaki campus in favour of consolidating in the city core, Grafton and Newmarket.
Yesterday, Mayor Len Brown announced an unconditional agreement, saying it was one of the most significant urban park acquisitions in Auckland's history.
But the purchase was an unbudgeted item and had to be factored into the 2014-15 draft annual plan to be finalised next year.