The Lilywhites took an 11th-minute lead when Darel Russell slotted home following a pass from Danny Mayor.
Mayor sealed victory midway through the second half when he picked up the ball and curled a right-footed shot into the bottom right-hand corner from 25 yards.
Preston now travel to St Mary's to take on the Saints on Wednesday, September 21.
There was, though, a silver lining for the Addicks, who returned to the top of League One after previous leaders Sheffield United were beaten 3-0 at home by Huddersfield.
