ASB chairman Gavin Walker is to retire from the bank's board at the end of August.
Walker, who has been on the board since March 2010 and chairman since August 2011, will be replaced by current director Dame Therese Walsh.
Walsh is also chair of Air New Zealand.
Walker said ASB had been an incredibly interesting and rewarding part of his business life for more than a decade.
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"It has been a privilege to work alongside a talented team of fellow directors and senior managers to collectively guide its growth and development over this time".
He paid tribute to the two chief executives he has worked with during his chairmanship, Barbara Chapman and Vittoria Shortt. "I've been lucky to work alongside two very talented, capable and inspiring leaders."
Walker said he was delighted Dame Therese had agreed to take up the chairmanship role.
"Dame Therese has been an ASB director since 2015 and currently chairs the board audit and risk committee. She knows our business well and has strong governance experience, notably as the chairman of Air New Zealand. I will step away feeling very confident about the future direction of the bank."
Dame Therese Walsh will take over the chairman role on 1 September 2021.
She will relinquish the chairmanship of the board audit and risk committee at that time.
She has recently retired from other appointments to focus on her roles at ASB and Air New Zealand.