The court on Sunday gave Mahmud Dabbus 10 years in prison for spying for a foreign state and another 25 years for plotting to kill Mubarak.
The court also sentenced in absentia Iranian diplomat Muhammad Hosseindost to 25 years in prison for recruiting Dabbus and plotting terror attacks and political assassinations in Egypt.
Dabbus said during his trial that he made confessions under pressure about planning to kill the president.
"This is unfair. I'm innocent," Dabbus said after the sentence was announced, claiming to reporters that he had been promised a presidential pardon if he cooperated with the investigation.
Judge Adil Abd al-Salam Jumaa of the state security court, who announced the sentences, denied that such a promise had been made.
"The holding of such a show trial was only aimed at pleasing the Zionist regime. The Egyptian judiciary should instead look into the problems in their own country"
Hamid Reza Asefi,
Foreign Ministry spokesman
Iran, which has denied the allegations, has not had full diplomatic ties with Egypt since the Iranian revolution in 1979, when Tehran broke off relations because Egypt had signed a peace treaty with Israel.
Hosseindost worked in the Iranian interests office in Cairo.
Iran immediately rejected what it said was the "ridiculous" sentencing and accused Egyptian authorities of only seeking to please Israel.
"This entire scenario was baseless from the very beginning and void of any evidence," Iranian Foreign Ministry spokesman Hamid Reza Asefi said in a statement carried by official media.
"The holding of such a show trial was only aimed at pleasing the Zionist regime. The Egyptian judiciary should instead look into the problems in their own country," Asefi added.