The win saw PNE move up to third in the table despite only being able to name six substitutes on the day, using none.
Goals from Neil Mellor and Richard Chaplow in either half gave Alan Irvine’s men all three points, with Bruno Berner netting a 90th minute consolation.
It was the first home defeat in over a year for Nigel Pearson’s side, who had won League One the season prior. Lining up for the Foxes was future PNE captain and current first team coach Paul Gallagher.
City dominated the early stages without really threatening Andy Lonergan's goal but Preston looked dangerous on the break and should have gone ahead in the 16th minute. Billy Jones' low cross looked like being turned in by the unmarked Chris Sedgwick at the far post but the midfielder blazed his shot over the crossbar.
At the other end, Lonergan kept his side ahead by blocking Matt Oakley's shot with his feet with Gallagher heading the rebound onto the roof of the net.
The opening goal came from a mistake by Richie Wellens in the 42nd minute. He headed Wayne Brown's clearance back into his own penalty area instead of directing the ball clear and Brown seized possession and showed quick feet to set up strike partner Mellor, who clinically steered the ball into the bottom corner from 15 yards.
Weale then kept his side in the game with a point-blank save to deny Mellor a minute before the break.
Preston doubled their lead after 66 minutes when Mellor broke from the edge of his own box, he carried it to the edge of the opposition box where he squared the ball for Chaplow to shoot underneath Weale.
Leicester were given hope in the 90th minute when Lonergan parried Gallagher's shot into Berner's path and the full-back returned the ball into the bottom corner.
PNE: Lonergan, Chilvers, Jones, Nolan, Collins, Chaplow, Sedgwick, Sumulikoski, Wallace, Brown, Mellor