The diplomatic mission was reopened in a ceremony attended by a number of Iranian and Saudi officials.
Also on Wednesday, the Islamic Republic reopened its office to the Organization of Islamic Cooperation, a Jeddah-based intergovernmental organization made up of 57 member states that works to protect the interests of the Muslim world.
A day earlier, Iran reopened its Embassy in the Saudi capital Riyadh, more than three months after the two countries agreed to resume diplomatic relations under a deal brokered by China.
The two regional countries re-established relations after more than seven years. They severed ties over a dispute on the Saudi execution of a prominent cleric.
Iran has named Alireza Enayati as its ambassador to Saudi Arabia.
4194