Prior to last week's race at Michigan International Speedway, Ambrose had not won a pole in 133 starts in the Sprint Cup series.
He turned a lap around the 1.99-mile road course in 95.262 mph.
"I am glad we could convert the effort into a great result," Ambrose said. "It is only one lap and we have to do a lot more on Sunday, but at least we can go home and say we had the fastest car."
A road-course specialist, Ambrose has finished sixth or better in the last three races on this track. His only Sprint Cup victory came last August on the road course at Watkins Glen, N.Y.
Current points leader Matt Kenseth qualified ninth.