Davis learned to roller-skate at age two and a year later was skating so fast that he had to be slowed by the rink's skate guards. He switched to ice skating at age six, a few months before his mother enrolled him in a local speed-skating club. Soon thereafter, Davis began to win regional competitions. At 17 he moved to Marquette, Mich., to improve his training opportunities. Although Davis was tall (1.88 metres 【6 feet 2 inches】) for a speed skater, his talent quickly overcame this apparent disadvantage, and he qualified for both the U.S. short-track and long-track teams for the 1999 junior world championships.

In 2005 Davis became the fourth American and the first black to win the world all-around speed-skating championship. On Feb. 18, 2006, he skated a 26.60-sec final lap to win the men's 1,000-metre long-track final at the Winter Olympic Games in Turin, Italy. Three days later he captured the silver medal in the 1,500 metre. Davis's success continued at the 2006 world speed-skating championships, where he won a second all-around title, posting a world-record overall score of 145.742 points. He also broke the world record for the 1,500 metre, adding that to the 1,000-metre record he had set in November 2005. In 2009 Davis won the world speed-skating sprint championship, becoming the second man (after Eric Heiden (Heiden, Eric)) to win both all-around and sprint world championships over the course of his career.