In just his fourth career series start, Bourdais took the checkered flag in the 165-lap London Champion Car Trophy by 7.835 seconds ahead of Newman/Haas teammate Bruno Junqueira of Brazil at Brands Hatch.
"I am very pleased about the win and especially to do it here in Europe where I won my first race," Bourdais said. "We should have won a couple earlier in the year and had troubles."
The Frenchman used very good fuel mileage and took the lead at the first round of pit stops on lap 55 and held it until 116 when Canadian Alex Tagliani gained the position for the next 15 laps.
Bourdais again moved to the front on lap 133 to remain there en route to the checkered flag. He led for 95 laps and averaged 105.412 miles per hour in a Ford-Cosworth/Lola.
Tagliani lost some positions on the final pit sequence and finished eighth.
Mario Dominguez of Mexico finished more than 11 seconds behind the winner in third.
Pole sitter Paul Tracy of Canada, who won the season's first three races, led for the first 54 laps and earned a single point on the day after a mechanical failure forced him out after 118 laps of competition.
Tracy remained the series leader with 65 points. Junqueira made up a lot of ground and is 11 points behind after four events.
Michel Jourdain of Mexico was sixth and stands third in points with 42.
The race had only two cautions for six laps.
The circuit stays in Europe for Sunday's German 500 at the Eurospeedway in Lausitz.