A rare moment of skill in a dour FA Cup semi-final dress rehearsal earned Arsenal victory as Robin van Persie scored his sixth goal of the season.
Just before half-time, the Dutchman turned exquisitely on the edge of the area before rounding Brad Friedel and sliding the ball into an empty net.
After the break, Van Persie hit the bar as Arsenal pressed for a second.
A Brett Emerton shot on 82 minutes and a first-half Morten Gamst Pedersen header were Rovers' best opportunities.
Pedersen's impressive leap earned Blackburn their first chance but he could not trouble Gunners keeper Jens Lehmann with his effort.
And neither keeper was regularly tested in the opening half, as the majority of the football was congested into the middle third of the pitch.
With Blackburn the joint lowest scorers in the Premiership and Arsenal lacking Dennis Bergkamp and Thierry Henry, a lack of goals could have been predicted.
Rovers' approach play was laboured, while Arsenal's seemed non-existent - and both sides found retaining possession a mission impossible.
But looking to be up for the challenge, David Thompson tricked his way past Gael Clichy only to end his solo run with a tame shot.
At the other end, Van Persie looked lively, but a little lightweight alongside Reyes.
Matthieu Flamini and Steven Reid battle for possession
No muscle was required, however, when he shimmied past the Rovers defence, which had just lost Dominic Matteo to injury, after collecting Ashley Cole's pass.
Confronted by the on-rushing Friedel, Van Persie made it look a simple task to dummy his way past the American and slot home.
Appearing revitalised after the interval, Arsenal fashioned a chance to add to their advantage almost immediately.
Following a number of slick one-twos, the ball was worked to Reyes in the penalty area but Friedel was equal to the Spaniard's low shot.
Blackburn, missing the bite of injured midfielder Robbie Savage, were struggling to compete.
They were close to conceding again when Reyes picked out an unmarked Van Persie, who crashed a shot against the bar.
But Rovers have been resilient of late and the hosts began to battle their way back into the game.
They might have been celebrating an equaliser had Emerton done better with a driven shot after he had been found in space on the right.
And Steven Reid had a late chance after Kolo Toure slipped but it was not to be, and would probably have been undeserved.
But the sides will meet again in Cardiff on 16 April for a place in the FA Cup final.
Blackburn boss Mark Hughes:
"We did okay in the first half but conceding the goal when we did deflated us a bit and we struggled in the second half.
"We found it really difficult to get any sustained momentum and we lacked a bit of energy.
We huffed and puffed, but the longer the game went on, the less likely it looked that we would get a goal."
Arsenal boss Arsene Wenger:
"We had a very young squad against a team that fighting to stay in the league. I think we coped well.
"The fluency of the passing was not the greatest, but it is very important for a young squad to win these types of games and I am very happy.
"With the lack of experience we had, we did very well. We didn't give away many chances. It's a big three points."
Blackburn: Friedel, Neill, Todd (Tugay 45), Nelsen, Matteo (Johansson 42), Mokoena, Thompson, Flitcroft (Emerton 60), Reid, Pedersen, Dickov.
Subs Not Used: Stead, Enckelman.
Booked: Dickov, Neill, Reid.
Arsenal: Lehmann, Lauren, Toure, Senderos, Clichy, Fabregas, Vieira, Flamini, Cole, Van Persie, Reyes.
Subs Not Used: Ljungberg, Taylor, Cygan, Eboue, Owusu-Abeyie.
Goals: Van Persie 43.
Ref: G Poll (Hertfordshire).