The French striker scored after 22 and 54 minutes to lead the Toffees charge towards a second home victory in four days.
Defender Joseph Yobo grabbed the third for the hosts, tapping home after the impressive Paul Robinson denied Saha a hat-trick goal.
David Moyes' side had endured a slow start to the campaign but appear to be back on track after following Thursday's 4-0 Europa League rout of AEK Athens with another fine win and clean sheet at Goodison Park against a disappointing Rovers side who were looking to haul themselves out of the relegation zone.
While Moyes' worries look to be easing, Rovers boss Sam Allardyce must be seriously concerned now about his side, who have won just one league game all term and were feeble for much of this clash.
Everton went in front when Leighton Baines fired in a free-kick from the left and Saha arrived at the near post to turn the ball past Robinson.
Blackburn responded with a couple of headers from Christopher Samba and a twisting run and shot from Dunn which was held by Tim Howard.
But the hosts remained in control and extended their lead after the break as Fellaini's cross sailed in from the right and Saha got above Pascal Chimbonda with ease to send his header wide of Robinson's dive.
Everton then grabbed a third when Baines' corner from the right struck Ryan Nelsen and fell invitingly for Yobo to fire in from close range.
And although Rovers continued to scrap in search of a way back into the game, the Toffees were rarely troubled as they completed an impressive victory.