Mohammad Eid Mohammad Dabbous was also found guilty of plotting to carry out terrorist acts in Egypt and Saudi Arabia.
The verdict came amid very tight security, with the court ruling Dabbous tried to "align himself with the devil to assassinate the symbol of Egypt," in reference to President Hosni Mubarak.
The court said Mohammad Reza Dost, an Iranian diplomat in Cairo, recruited Dabbous to enlist other Egyptians to carry out "acts that harm Egyptian and Saudi national interests and their ties."
Dost was sentenced in absentia to 25 years in prison for training and preparing Dabbous to carry out attacks in both Egypt and Saudi Arabia.
Iranian officials have denied the allegations against the diplomat as "baseless," while Dabbous also maintained his innocence.
He told United Press International from behind bars in the courtroom "I only visited Iran twice to establish an Egyptian-Iranian friendship society, and the Egyptian authorities know this."
Dabbous insisted the entire case against him was fabricated, adding his confession was extracted under torture.