Young's penalty broke the deadlock early in the second half and, after an own goal from Rovers defender Grant Hanley, Downing also got on the score-sheet before Nikola Kalinic's consolation.
Young's stunning strike completed the scoring eight minutes from time and Blackburn skipper Ryan Nelsen was sent off in injury time for a second bookable offence.
Villa have now taken 12 points from their last seven Premier League matches to climb into mid-table.
Watching England head coach Fabio Capello must have been impressed by Young who is relishing playing in the central role behind Darren Bent.
Downing and on-loan Tottenham right-back Kyle Walker also caught the eye down the flanks.
Veteran midfielder Robert Pires also had his most influential game for Villa.
Rovers had little to offer as an attacking force and finished well beaten.
Rovers keeper Paul Robinson was called into action for the first time in saving a low drive from Bent at the second attempt after good play by Young.
Rovers defender Martin Olsson ventured forward but dragged his shot well wide.
Jermaine Jones became the first player to be yellow carded after 23 minutes for bringing down Pires from behind.
Nelsen should have done better when he got on the end of a deep Morten Gamst Pedersen corner but he could not keep his header down.
Villa had strong appeals for a penalty rejected when Pires' fine pass found Bent who went down after a challenge from Grant Hanley but referee Martin Atkinson waved play on.
Nathan Baker needed lengthy touchline treatment after being caught by Robinson when punching clear a Downing cross.
The teenager appeared to be suffering from concussion and had to be replaced after 36 minutes by Fabian Delph.
Villa built up some momentum and Robinson beat out a powerful effort from Pires after Young had teed him up with a first time pass.
Then the former England keeper parried away a drive from Walker and the rebound was put over the top by Young.
The home side were building up some momentum and Robinson pushed another Pires attempt to one side.
Bent almost took advantage of a defensive mix-up but tried to cut back inside and the chance went begging.
Vince Grella was booked in first half injury time for chopping down Pires.
A mistake by Richard Dunne almost proved costly for Villa in the first minute of the second half.
Roque Santa Cruz played in Jones and his low shot was beaten away by former Blackburn keeper Brad Friedel.
Villa were quickly back on the offensive and a fine ball from Pires played in Downing whose shot was deflected wide.
The home side's dominance was finally rewarded after 49 minutes with Young putting Villa ahead from the penalty spot.
Keith Andrews lost possession to Young and the Rovers defender brought down the England player.
Up stepped Young to send Robinson the wrong way with the spot-kick for his seventh goal of the campaign.
Villa took control of the match by netting twice more in the space of 60 seconds.
After 62 minutes Hanley could only deflect a low centre from Marc Albrighton past his own keeper.
Rovers manager Steve Kean then brought on Jason Roberts and Nikola Kalinic in place of Vince Grella and Santa Cruz.
But immediately Villa made it 3-0 through Downing.
Downing cut in from the right after seizing onto Young's dinked pass and coolly beat Robinson with a shot into the far corner of the net.
Pires left the field to warm applause with 15 minutes remaining and was replaced by skipper Stiliyan Petrov.
Acting captain Young offered Petrov the armband but he declined to take it.
Kalinic gave Rovers a glimmer of hope after 81 minutes when his shot took a deflection of Dunne and flew past Friedel into the net.
But Villa were soon back on the offensive and Young made it 4-1 in superb fashion.
Downing was the creator with his cross from the right and Young's powerful first time shot flew past Robinson.
Blackburn's misery was completed with Nelsen's dismissal when he was shown a second yellow card.