Having outclassed American world No. 4 Carl Alan Nickolas in straight rounds for a place in the final, Barkhordari – a world bronze medalist last year – came out victorious against Apostolos Telikostoglou in the showdown to earn 60 Olympic qualification points.
The Iranian won a thrilling first round 8-6 but was stunned by a late fightback from the Greek, who landed a turning kick with 10 seconds left on the clock for a 9-7 win, forcing the bout into the decider.
Barkhordari shook off the second-round disappointment with three successive punches for a three-point advantage and then never looked behind as back-to-back head kicks extended his advantage to 9-0.
A former silver winner at the event, Barkhordari rounded off a 12-0 triumph with a final head kick to grab the gold.
Matin Rezaei, meanwhile, finished his -68kg campaign empty-handed after a defeat against Jordanian Ziyad Kareem in his second bout.
Barkhordari’s gold came after the Iranians had scooped three medals on the preceding night.
Mahdi Hajimousaei and Abolfazl Zandi completed a one-two in the men’s -58kg event, with the latter withdrawing from the final showpiece to boost his fellow 19-year-old’s chances of securing a berth in next summer’s Olympics in the French capital.
Iranian teenage girl Mobina Ne’matzadeh got off to a brave start against Tokyo Olympic silver medalist Adriana Cerezo of Spain in the -49kg semis, winning the first round, but eventually fell to a 2-1 defeat and settled for a joint bronze – alongside China’s Xiaolu Wang.
Turkey’s Merve Dincel defeated the Spaniard for the gold.