The decision by interim President Adly Mahmoud Mansour, who was installed Thursday by the military, was certain to infuriate Muslim Brotherhood supporters, who are demanding that ousted President Mohamed Morsi be restored to office.
But anti-Morsi protesters, including members of the Rebel movement that organized mass protests against Morsi last week, pushed for ElBaradei to receive the job.
ElBaradei was expected to be sworn in Saturday evening.
ElBaradei, 70, was seen as a favorite due to his long-standing position as an opposition leader, first against President Hosni Mubarak, who was deposed in February 2011 and then against Morsi. His reputation as former head of the International Atomic Energy Agency and as winner of the 2005 Nobel Peace Prize should send a positive message to a global community increasingly alarmed by Egypt’s chaos.
But the attorney has struggled in recent days to reconcile his support for democracy and rule of law with a military coup that unseated Egypt’s first democratically elected leader. He has portrayed the coup as a “recall,” saying extraordinary measures were needed to avoid a civil war.
Islamist groups, particularly the Muslim Brotherhood, have criticized ElBaradei -- who spent much of his life living abroad -- as a foreign agent with liberal values.
For the military, ElBaradei also represents somewhat of a risk since he is not an anonymous technocrat who could be easily manipulated or intimidated.
ElBaradei's rising influence was signaled Wednesday when he appeared alongside Gen. Abdel Fattah Sisi when the commander of the armed forces went on television late Wednesday to announce that Morsi was no longer president.