The 25-year-old headed across to pond in confident mood having already claimed gold and silver from the opening two World Cup races of the season.
And she can now boast to have picked up a medal of every colour in the first three races of the campaign as she picked up bronze in Lake Placid.
Yarnold sat seventh after the first run but improved to post the second-fastest time in her second attempt for a total time of 1:51.88 minutes.
American Noelle Pikus-Pace gave the home crowd plenty to cheer as she came first, with Germany's Anja Huber finishing second.
But there was also plenty more for Team GB to celebrate as Shelley Rudman came home sixth in 1:52.22, Donna Creighton placing 16th.
The result means Yarnold sits atop the World Cup leaderboard on 635 points, with Huber second on 562 and Rudman she two points further back in third.
In the men's event Dominic Parsons was the highest-finishing Brit as he placed 11th, with Kristian Bromley seven places further back and Ed Smith 24th.
Matthew Antoine made it two victories for the home crowd as the American came home first in 1:47.58, with Russian Alexander Tretiakov second and Tomass Dukurs completing the podium in third.
Tretiakov remains atop the World Cup leaderboard on 645 points with Martins Dukers 50 points further back in second and Antoine in third – with Parsons the highest ranked Brit in seventh on 480.