"He's a hell of a fighter," said Dawson, a light-heavyweight champion who moved down in weight to challenge Ward. "He's a great champion. He's the best."
Dawson, boasting a 31-2 record (17 KOs), started brightly, keeping Ward off balance with a strong southpaw right jab in the first round, and then scoring with counter left hooks as Ward looked to press the action in the second.
By the third, however, Ward (26-0, 14 KOs) was timing his opponent with sharp left jabs and hooks, using swift footwork to throw Dawson off.
A short hook near the end of the third dropped Dawson, and another one knocked him down again at the start of the fourth.
Ward pressed the advantage in that round, nearly putting Dawson down again and pursuing him across the ring.
The challenger survived, however, and for the next several rounds some of the steam evaporated from the contest, as Dawson appeared content to keep Ward at bay with jabs and by tying him up when the two men were close.
Ward was relentless, however, and a sharp right hand in the ninth round buckled Dawson's knees again.
In the tenth, a three-punch combination had Dawson wobbling on his legs and a follow-up barrage knocked him to his knees.
Although Dawson beat the count, he signaled to referee Steve Smoger that he had had enough.
It was Ward's first stoppage win in three years, and the champion said the quality of his opponent had caused him to raise his game.
"All we did was eat, sleep and drink this guy, because you can't take a chance on someone like Chad Dawson," he said. "He's beaten future Hall-of-Famers."
Dawson, the reigning WBC light-heavyweight champion, whose most recent win was over veteran Bernard Hopkins, said he would be returning to that weight division.
"I'm not going to hang my head low. I'm still light-heavyweight champion of the world," he said.
However, Ward may have eyes on that title, too.
"A move to light-heavyweight is not out of the question," he said.