Hedrick became the first United States athlete to claim a gold at these Games by defeating world record holder Sven Kramer in the 5,000-meter speed skating event.
The race also produced the first medalist from the host country.
Hedrick was timed in 6:14.68 while Kramer finished in 6:16.40 -- almost eight seconds off the world record he set last November. Italian Enrico Fabris grabbed the bronze in 6:18.25, touching off a celebration inside the Oval Lingotto.
Hedrick has his sights on the Olympic record of five individual gold medals in one Games, set by speed skating legend Eric Heiden at Lake Placid in 1980.
Kramer had the best times for the first three of the 13 check points, but Hedrick moved ahead at the fourth and steadily built his advantage.
American Shani Davis, considered a likely medalist, went out too fast before tiring noticeably en route to a seventh-place finish.