A Robert Pires goal and a late Robin van Persie double saw Arsenal book their place in the FA Cup final.
A poor semi-final saw more bookings than goalscoring chances in front of a disappointing below-capacity crowd.
Pires finished off from close range after good work from defender Kolo Toure three minutes before half-time.
Van Persie came off the bench to seal it with a fine individual effort and then a curling left-foot shot past Brad Friedel after being set up by Pires.
The Gunners started the game as firm favourites, even without injured striker Thierry Henry and key defender Sol Campbell still not ready to return.
It is the fifth successive season they had made the last four of the FA Cup - equalling the competition record - and they have now made the final four years out of five.
Blackburn had threatened to spoil the party early on, with their five-man midfield harrying Arsenal's players and contesting every pass.
The gameplan worked a treat for more than half an hour, with Arsenal boss Arsene Wenger showing his frustrations on the sidelines at his side's inability to threaten Blackburn's goal and Rovers' heavy-handed efforts.
At the other end Blackburn threatened with Morten Gamst Pedersen firing a free-kick over the bar and Steven Reid testing Jens Lehmann with a low-driven effort.
Just before the half-hour mark Arsenal got their first sight on goal, but Jose Antonio Reyes failed to get hold of his left-foot shot and Friedel saved easily.
On 37 minutes Arsenal finally found a hole in the Blackburn backline.
Dennis Bergkamp put Reyes through on goal but Friedel reacted brilliantly to deny his low shot with his outstretched right hand and the follow up from Pires' effort was blocked away by Friedel and Pederson.
Three minutes before half-time Arsenal got the breakthrough, with Toure the unlikely creator.
Patrick Vieira's chipped pass found Toure at the back post and he outwitted Ryan Nelson before looking up and picking out Pires to tap in.
Robert Pires scored just before half-time
With Blackburn having to come forward the second half was a more open affair, even if goalscoring chances were not exactly forthcoming.
Arsenal could have had a second when Fabrice Fabregas and Lauren conspired to set up Gilberto Silva for a shot on goal that Friedel again reacted well to beat it out.
The Gunners looked far more comfortable, no longer having to chase the game and they demonstrated this by stringing together a sequence of more than 40 passes.
Blackburn threw on Brett Emerton and Robbie Savage and the former came closest to grabbing them an equaliser, but his long-range effort was easily gathered low down by Lehmann.
Arsenal secured their place in the final when Van Persie turned Lucas Neill before running on and slotting past Friedel and into the bottom corner.
With four minutes to go Pires broke down the left before picking out Van Persie and his first-time effort curled past Friedel and just inside the post.
Arsenal: Lehmann, Lauren, Senderos, Toure, Cole, Pires, Silva, Vieira, Reyes (Aliadiere 90), Ljungberg (Fabregas 50), Bergkamp (Van Persie 82).
Subs Not Used: Almunia, Cygan.
Booked: Toure, Fabregas, Cole.
Goals: Pires 42, Van Persie 86, 90.
Blackburn: Friedel, Neill, Todd, Mokoena, Nelsen, Matteo (Stead 83), Pedersen, Flitcroft (Emerton 51), Reid, Thompson (Savage 63), Dickov.
Subs Not Used: Enckelman, Tugay.
Booked: Flitcroft, Thompson, Mokoena, Neill.
Ref: S Dunn (Gloucestershire).