The win, in a combined time of two minutes 25.59 seconds, was the American's 13th in the discipline and the third at Beaver Creek as he again pleased home fans with two blistering runs.
The giant slalom world champion, who won the season opener in Soelden with a record lead of 2.75 seconds, was a little less impressive this time, but still left second-placed Austrian Marcel Hirscher a huge 1.76 behind.
Italy's Davide Simoncelli was third, 2.07 adrift, for his first podium in more than two years.
"It was a great battle today and a special feeling. I'm proud to have shown to the American fans what I can do," said Ligety, still sporting the moustache he grew after November was declared the moustache month.
"It's not the same when you know that everybody at the bottom is expecting you to win and to do it by such a margin," he added.
"Obviously, after Soelden, I had a little bit of pressure on my shoulders. It remained to be seen whether I could repeat the same race and the same gap. It's true it looks a little bit like Hermann Maier when he won his races by two seconds but I'm not looking for that. I try to race like Ligety."
His victory crowned a perfect weekend for the U.S. Ski Team after the treble achieved by Lindsey Vonn in Lake Louise and the three runner-up spots earned by Stacey Cook and Julia Mancuso.
Yet, like Vonn, Ligety said the race had been far from a piece of cake.
"It was not easy today," he said. "I could not believe I was first after the first run because I had a terrible feeling all the way down. I had the impression I was doing everything wrong."
Norway's Aksel Lund Svindal was sixth and retained his overall World Cup lead with 400 points ahead of Ligety, who is on 320.
The two appear the most serious threats to World Cup holder Hirscher, who was again impressed by Ligety whom he beat for the giant slalom World Cup last winter.
"With a skier like Ligety, you don't know how long it's going to last, two weeks, two months or two years, but I'll keep fighting to stay in the race at all cost", he said.
Hirscher said he had good feelings in Saturday's Super-G on the Birds of Prey course and was less afraid than in the past by speed events.
The men's circuit moves to Val d'Isere in France next weekend, a resort in which the Austrian earned his first laurels.
"I love Val d'Isere and I think Val d'Isere loves me," he said.