Former Prime Minister John Key has been named to the board of Australia New Zealand Banking Group, having served as chair of the lender's New Zealand unit since January.

"Following a successful international career in business and politics, Sir John has the ideal credentials to further strengthen ANZ's board," the Australian lender's chair David Gonski said in a statement.

"Our New Zealand business has already benefited from his significant experience and I know he will make a valuable contribution to the ongoing success of the broader group."

Mr Key's appointment is effective immediately although he will stand for election at the bank's annual meeting on December 19.

He first joined the board of ANZ New Zealand last October before being named chair.

Prior to his career in politics, Mr Key worked in the financial markets including as head of foreign exchange at Merrill Lynch.

He was knighted in the 2017 Queen's Birthday Honours and is also the recipient of the Companion of the Order of Australia for his work on the bilateral relationship between the two countries.