Zanjani became notorious during the era of president Mahmoud Ahmadinejad, finding ways to channel hard currency from oil sales to Tehran despite financial sanctions imposed on the Islamic republicâ€™s banks as punishment for its nuclear programme.
The trial was held in public, a rarity for such a major case in Iran, and two other accused were also convicted of â€œcorruption on earthâ€, the most serious offence under the countryâ€™s criminal code, meaning they too will face the death penalty.
â€œThe preliminary court has sentenced these three defendants to be executed, as well as paying restitution to the plaintiff,â€ Mohseni-Ejeie said, adding that that was the oil ministry.
They must also pay a â€œfine equal to one fourth of the money that was launderedâ€, the spokesman said, without specifying the sum.
Zanjani, who can appeal, had denied any wrongdoing, insisting that the only reason the money had not been paid to the oil ministry was that sanctions had prevented a planned transfer from taking place.
However, the case follows repeated declarations from the current government of President Hassan Rouhani that corruption and the payment of illegal commissions thrived under Ahmadinejadâ€™s rule.
Zanjani had repeatedly said in media interviews that in return for commissions paid by Ahmadinejadâ€™s government he was tasked with circumventing sanctions to get money back to Iran.