Beslan Mudranov gives Russia, which was in danger of a blanket ban from the Games, a first gold medal at the Rio de Janeiro Olympics, in judo's 60-kilo event.
The two-time European champion Mudranov, 30, beat Kazakhstan's Yeldos Smetos with a golden score Waza-Ri.
Russia escaped a full Olympic ban when the International Olympic Committee (IOC) decided to let the respective sports federations decide on Russian participation in Rio in the wake of grave allegations of widespread and state-sponsored doping in the country.
Using strict criteria, with a final saying from the IOC, almost 280 Russians are now eligible to compete. They include the 12-strong judo team.