He's the first person ever to win back-to-back golds in the event.
Davis edged out a South Korean skater to claim the gold medal. He won gold four years ago and is the reigning world-record holder. American Chad Hendrick took the bronze.
Davis became just the third American man to win more than one speedskating gold medal.
"When you're a world champion or an Olympic champion, you get this little thing on your back called a target," Davis said. "To go out there and win the 1,000 meters twice is truly amazing."
Davis dug deep on his final lap, knowing he needed a little more speed to catch South Korea's Mo Tae-bum. The American swung both arms twice before leaning into the final turn, giving him just enough of a boost for a time of 1 minute, 8.94 seconds.
Mo, who won gold in the 500 two days earlier, settled for silver this time, 18-hundreths behind Davis. Hedrick was next in 1:09.32.
Davis will race again Saturday in the 1,500. Davis is the world-record holder in that event, just as he is in the 1,000.
When he won the 1,000 four years ago, Davis became the first African-American athlete to win an individual gold at the Winter Games. This time, he simply wanted to be known for his skating.
After spotting his winning time, Davis pumped both fists and slapped hands with the U.S. coaches on the backstretch.
Davis won a gold and silver in 2006.
The Associated Press contributed to this report.