Ayatollah Seyed Hashem Bathaei, who had been hospitalized a few days ago, died on Monday.
He represented the people of Tehran in the assembly.
The Assembly of Experts is a high-ranking body that elects and oversees the activities of the leader of the Islamic Revolution.
Iran has been battling the coronavirus outbreak for nearly a month.
Health Ministry Spokesman Kianoush Jahanpour said on Sunday that 1,209 fresh cases were added to the number of confirmed infections during the past 24 hours, adding, “The good news is that more than 4,590 of the overall confirmed cases have recovered.”