A thunderous first half strike from Paulo Jorge was followed up by a close-range effort from Jordan Preston in the second as the young Rovers deserved all three points.
Eric Kinder's side were pegged back on the half hour when Rolando Aarons netted for the visitors, but it was a rare effort from Newcastle United as Rovers had the better of the match throughout.
It was two young sides that took to the field at a chilly Ewood Park, with little between them in the opening stages.
The game sprang into life in the 12th minute - and how. As Rovers attacked through midfield, Paulo Jorge spread play onto debutant Hyuga Tanner before receiving the ball back and unleashing an unstoppable strike from 20 yards that flew into the back of the net via the underside of the crossbar.
It was the midfielder's first goal in a Rovers shirt.
The game continued to be nip and tuck between the two sides until the half hour when the visitors drew level.
Adam Armstrong threaded the ball through the Rovers back line for Rolando Aarons to race clear and finish well past the advancing Simon Eastwood.
Rovers ended the first half the stronger but without success, Devarn Green, making a welcome return to the starting line-up, going close with a shot from 25 yards that flew narrowly over the bar.
The home side maintained that form going into the second half and ten minutes after the turnaround they were back in front.
A corner from the left from trialist Peter Smith found Devarn Green, and although his shot was blocked, as the ball was worked back into the box Ryan Edwards nodded goalwards to where Jordan Preston was on hand to apply the finishing touch from close-range for this third Under-21 goal.
There was a lengthy stoppage just past the hour mark after a Rovers corner ended with Liam Gibson down for an extended length of time, the young full back was eventually stretchered off.
Rovers picked up where they left off with further attacks but they couldn't grab that third goal to make the game totally safe.
It wasn't for the want of trying as Jordan Preston, Devarn Green, Paulo Jorge and substitute Luke Wall all went close in the latter stages.
Nine additional minutes thankfully passed without drama as a delighted Rovers deservedly claimed the points.
ROVERS: Eastwood, Fernandez, Beesley, Tanner (sub Doyle 84 mins), Edwards, Lenihan (c), Paulo Jorge, Bauress, Preston, Green (sub Wall 87 mins), Smith.
Subs not used: Pero, Raya, Cham.
Goals: Paulo Jorge 12 mins, Preston 55 mins.
NEWCASTLE: Mitchell, Sterry, Gibson (sub McKinnon 70 mins), Bigirimana (sub Gilliead 61 mins), Williams, Satka, Richardson, Olley, Quinn (sub Roberts 90+2 mins), Armstrong, Aarons.
Subs not used: Pearson, Barlaser.
Goals: Aarons 29 mins.