The ceremony was attended by Iranian President Ebrahim Raisi and his Venezuelan counterpart Nicolas Maduro, who is in Tehran on an official visit.
They were linked via video-conference to the deck of the vessel that is in the Persian Gulf waters.
The two presidents were also briefed on the construction and operation of the tanker.
At the ceremony, documents related to the delivery of the tanker were signed by the two countries’ officials.
The Iranian Marine Industrial Company (Sadra) has manufactured the ocean-going oil tanker, the second one delivered to the Latin American country.
With a length of 250 meters, width of 44 meters and height of 21 meters on the deck, it can carry 113,000 tons of crude oil equivalent to 750,000 barrels.
According to a contract signed between the two sides, Iran is going to build and deliver two more oil tankers to Venezuela.
Earlier in the day, Raisi and Maduro signed a 20-year partnership agreement aimed at bolstering cooperation in various fields between Tehran and Caracas.