Mugabe is expected to be sworn in after a widely condemned one-candidate presidential election tainted by the withdrawal of opposition leader Morgan Tsvangirai because of violence and intimidation.
African Union leaders meet in Egypt in Monday, facing growing international pressure to take action against Mugabe.
"If you were to have a unanimous voice, saying quite clearly to Mr Mugabe...you are illegitimate and we will not recognise your administration in any shape or form - I think that would be a very, very powerful signal and would really strengthen the hand of the international community," Tutu, a South African Nobel Peace Prize laureate, said in an interview with the BBC.
Tutu said Mugabe should play no part in Zimbabwe's future and repeated his call for military intervention by a United Nations force spearheaded by African troops if necessary.
"That crisis has to be resolved sooner rather than later," he said. "I think that a very good argument can be made for having an international force to restore peace.
"Almost everybody will say that any arrangement after Friday's charade, that arrangement should be one in which Mr Mugabe certainly does not feature any longer."
