The 25-year-old, who started the torch relay for the Olympics on April 21 from his native Greece, gave a powerful display of control and strength on the apparatus crushing his rivals with an unbeatable 16.000 points.
Reigning Olympic champion Arthur Zanetti of Brazil had to settle for silver despite the huge expectations of the home crowd on his shoulders, scoring 15.766.
Russia's Denis Abliazin scored 15.700 to take bronze.
It is the third time that Greece have won the rings title but first outside their native country with Ioannis Mitropoulos winning at the 1896 Games in Athens, and Dimosthenis Tampakos claiming gold in 2004.
Dutch gymnast Yuri Van Gelder, who has also been dubbed 'Lord of the Rings', returned home in disgrace a week ago after being kicked off his country's Olympics team for a night out drinking in Rio.
The 2005 world champion had sealed a place in Rio in the men's rings finals, after coming seventh in qualifiers.