In a battle of two former world number ones, the ninth seed hammered down 17 aces and dictated play from the start, clinching his 21st career title in just 70 minutes.
"I'm so happy I turned it round here in Cincinnati this week," Roddick said.
Roddick kissed the court, did a lap of the arena and exchanged high fives with fans after wrapping up his fourth Masters Series title.
In a repeat of the 2003 U.S. Open final, which Roddick won, the American served superbly throughout and never allowed Ferrero a chance to get a foothold in the match.
Roddick broke serve in the second game but Ferrero, who had beaten James Blake, Rafael Nadal and Tommy Robredo en route to the final, hit back to break in the next game.
But Roddick broke again in the next game and held on to take the set before storming to a 5-2 lead in the second.
Roddick was broken when serving for the match at 5-2 but he made no mistake second time round, hitting three aces in succession to clinch a victory which will lift him back into the top 10 of the world rankings.
Despite the defeat, Ferrero, who has not won a title since 2003, will move back inside the world's top 20.
"This has been an important week for me, to get to the final," he said.
