Tretiakov won the bronze medal in Vancouver and became world champion in 2013.
On the sliding course in the mountains above Sochi, Tretiakov turned in the fastest time in three of the four runs to win the gold by .81 of a second over Martins Dukurs of Latvia. Dukurs was also the silver medalist in 2010.
The bronze went to American Matthew Antoine, who gave the United States its second medal during skeleton's brief appearance on the Olympic stage. Noelle Pikus-Pace won a silver for the United States in the women's event Friday.
Antoine and fellow-American John Daly were placed third and fourth going into the final run, but Daly's hopes for a medal disappeared during a difficult trip down the course.
Daly's sled turned sideways as he started the run and by the time he could get it headed in the proper direction he had lost all momentum.
He wound up with the worst time of the 20 contestants who were part of the fourth run and he dropped from fourth to 15th in the final standings.
Having seen his teammate struggle, Antoine had a less-than-perfect trip himself. It was only the sixth-best final run, but he held on to win the bronze by .32 of a second.