Crawford made the announcement at the company's annual general meeting in Perth today.

The 74-year-old stood for re-election at the AGM, but told shareholders he planned to step down during his next three-year term.

A succession process is already underway with the aim of announcing his replacement by this time next year.

Crawford was appointed as South32's first ever chairman in late 2014, prior to the company's demerger from BHP in May 2015.

Before that, Crawford had been a director of BHP for 20 years.

In June, Crawford also announced he would step down as chairman of Lendlease next month.

Crawford said it had been an honour to chair South32.

A representative from the Australian Shareholders Association told the meeting the group was planning to oppose Crawford's re-election due to his heavy workload.

Crawford is also a recently appointed director of Evans Dixon, chairman of the Australia Pacific Airports Corporation, and a member of Bank of America Merrill Lynch Australia's advisory board.

In light of Crawford's announcement, the ASA backed his re-election, and the resolution was passed with more than 95% in favour.