Mayor, 20, who had a brief spell on loan at Rovers in 2009, netted his first league goal for the Lilywhites when he fired home after 71 minutes at Deepdale.
The ever-reliable Graham Alexander had put Preston ahead from the penalty spot in the 37th minute but Jose Baxter levelled on the hour mark and the hosts had to cling on once Paul Parry saw red 15 minutes from the end.
Alexander put Phil Brown’s side ahead when he smashed a penalty into the corner after Neil Mellor was fouled by Ian Goodison.
Baxter – on-loan from Everton – grabbed a debut goal when he rammed home the rebound after Lucas Akins’ deflected effort hit the post.
Mayor slotted past Owain fon Williams before being replaced himself soon afterwards to counter the loss of Parry to a second yellow card.