The former Santos chairman was already a non-executive director and had been appointed as asset integration advisor to help with the transition following the merger of Glencore and Xstrata finished last month.
The other new appointees are Morgan Stanley senior advisor John T Mack and Bloomberg executive chairman Peter T Grauer as independent non-executive directors.
The new appointments come less than a month after the re-election of former Xstrata chairman Sir John Bond and directors Con Fauconnier, Ian Strachan and Peter Hooley were opposed by shareholders.
“The board is extremely pleased to be able to move forward with the appointment of three additional directors,” Glencore interim chairman Tony Hayward said.
“Each of them has an excellent business track record and extensive international experience, which we believe will prove invaluable in continuing the strength of debate and challenge which has typified the operation of the company’s board since its IPO two years ago.”
Hayward said the search for a new chairman was ongoing.
“As previously indicated, the board will consult with its major external shareholders as part of this exercise and will update the market as appropriate,” he said.