Callum Robinson and Joe Garner sealed all three points in the space of four second-half minutes with two well-taken goals.
Dons defender Kyle McFadzean had the first effort on goal after 17 minutes as both sides struggled to take a hold of the game during the opening exchanges.
McFadzean struck a powerful long-range effort from 25-yards, which looked set for the top corner, but Preston goalkeeper Sam Johnstone was able push the ball just wide.
Garner wasted a good opportunity for Preston when he fired over from eight yards after a neat cut-back from Daniel Johnson shortly after half-time.
But Robinson netted his sixth goal of the season for the visitors after 66 minutes with a left-foot strike across Dons keeper Ian McLoughlin before Garner doubled the lead four minutes later with a close-range header to seal a fourth consecutive away win for in-form North End.