A goal from Adam Davie and an own goal by Blackburn centre half Frank Jones saw the Rams handily placed with a two-goal cushion going into the half time break.
However, a ferocious fightback from the hosts, including two impressive free-kick conversions, saw substitute Mason Fawns convert a brace before Ben Williams struck the all-important goal, four minutes into injury time.
In the games early stages, both sides were unable to create any clear cut chances and it was the hosts who dominate possession.
On 11 minutes, Justin Walker and Rory Delap’s side caught Blackburn on the break and a late tackle saw Derby awarded a free-kick in a threating area – 25 yards from goal.
Creative play saw Joe Bateman fake over the ball, allowing Henry Wise to lay the ball off for Ayomide Jibodu – however, the Swedish wideman was only able to put the ball over the bar.
Despite the opportunity, though, it proved to be an anomaly as Blackburn continued to grow into the game.
In the 17th minute, successive opportunity’s fell Blackburn’s way inside the area, however, two committed clearances, first from Jordan Mills and then from Fuseine Rashid, ensured the score remained level.
Stubborn defending from the Rams had to be continued in order to keep the visitors in the game – particularly in the 32nd minute after the best Blackburn’s best opportunity fell their way when an error of judgement to come off his line saw Daniel Butterworth flick the ball over Matt Yates’ head.
Rovers looked certain to take the lead and would have done with relative ease had it not have been from a perfectly timed and executed sliding tackle from captain Joe Bateman.
With the match approaching half time, a change in the score line looked unlikely until a neat layoff opened up the space for Davie to test his efforts and he converted in impressive style, blasting the ball to the left of the goal from 20 yards out.
Minutes later, Derby doubled their lead after Jibodu produced a tricky cross from the left side, forcing the error on Jones who accidently put the ball in his own net.
As the referee called time on the first half, the Rams kick-off with a sharp restart, picking up where they left off.
However, it was Blackburn again who looked the most comfortable as the game progressed and that came to fruition when substitute Fawns capitalised on an error from Jayden Bogle to score and halve the deficit for his side.
The host seemed only to draw confidence after finding the net and the Rams defence was put under a considerable amount off attacking pressure, which it dealt with well until in the 84th minute when Fawns converted again – this time from a free-kick which he directed into the far top corner of Yates’ goal.
With the game looking almost certain for a share of points between the two teams – misfortune struck for the Rams after Blackburn were awarded a free kick outside the area.
Williamson stepped up confidently for Rovers and struck the ball in exceptional fashion – putting the ball in the top right corner of the net and sealing all three points for his in what was a spectacular comeback.
Derby County U18s: Yates, Bogle, Mills, Wise (Bird, 82), Bateman (C), Rashid, Jibodu (Davidson-Miller, 59), Edwards, Davie, Thomas, Cresswell
Substitutes not used: Fryatt, Thorne, Mbuti
Blackburn Rovers U18s: Ascroft, Jackson, Thompson (Robinson, 59), Mols (C), Makinson, Jones, Pemberton, Wright (Evans, 76), Butterworth (Fawns, 14), Curran, Williams
Substitutes not used: Carter, Campbell