The Newman/Haas Racing Lola started on the pole but spun out in the first turn and came from 13th place to take the checkered flag. The Frenchman crossed the finish line 7.446 seconds ahead of runner-up Paul Tracy.
The victory was Bourdais' fifth of the season and eighth of his Champ Car career.
Bruno Junqueira, Mario Dominguez and A.J. Allmendinger completed the top-five.
The next race in the championship, the Molson Indy Montreal, is scheduled for Sunday, Aug. 29.