The 18-year-old former Spurs youngster was thrown on as a substitute by Bantams' boss Stuart McCall and within two minutes he brought the crowd of over 13,000 to their feet with a sensational dipping volley from wide on the left.
Wrexham keeper Anthony Williams had already made a series of impressive stops to give the visitors a chance of snatching a second successive win, but he had no chance as Medley's thunderbolt flew beyond him from 30 yards out.
In fact Medley could have bagged a hat-trick as City stormed forward, but McCall will be happy that his side opened their win account with a first victory on home soil since December 16.
The City manager might have feared the worst after his side took the lead through midfielder Eddie Johnson only to see the Dragons hit back wihin five minutes.
The Bantams had dominated the first half but their efforts went unrewarded as Paul Evans saw his excellent volley tipped away by Williams and striker Guylain Ndumbu-Nsungu saw his deflected shot bounce back into play off the crossbar.
Bantams' keeper Donovan Ricketts did well to parry two long-range strikes from Wrexham dangerman Matty Done and City finally broke the deadlock after 49 minutes when Johnson raced onto a loose ball and drilled a right-foot shot beyond Williams from 20 yards.
Two minutes later Williams reacted sharply to keep out Mark Bower's near-post header and former Bantam Neil Roberts stunned the home side with his equaliser five minutes later.
City's defence had already survived a couple of scares before they failed to clear a Wrexham corner and skipper Roberts was left unmarked to head home Danny Williams' pull-back from eight yards.
Dragons' keeper Williams showed his sharpness again as he plunged to his right to push away a fierce Evans free-kick and Wrexham striker Michael Proctor was disappointed not to hit the target with his header soon after.
But Medley's dream strike 12 minutes from time revived City and he could have wrapped up the long-awaited win in the final ten minutes when he just failed to reach a low cross from winger Omar Daley and in City's next attack he headed another Daley cross just over the bar.