ANZ Bank chairman David Gonski has announced his retirement after six years in the job and will be succeeded by ANZ director and former CEO of telecommunications company Optus Paul O'Sullivan on October 28.

Mr Gonski joined the board at ANZ in February 2002 and served until June 2007 before returning to the board as chairman in 2014, taking his tenure as a non-executive director with the bank to more than 11 years.