Cardiff moved seven points clear at the top of the Championship with the victory.
Campbell nodded home his sixth for the club from five yards out to finally break the Rovers resistance five minutes before the break.
And it was Campbell's replacement Mason who doubled the lead with four minutes to go before substitute Whittingham wrapped up the points from the penalty spot in added time.
It took Cardiff just seven minutes to test Blackburn goalkeeper Jake Kean, the recalled Craig Bellamy warming the shotstopper's gloves with a 25-yard free-kick.
A minute later Campbell missed a fantastic chance to open the scoring after Kean struggled to deal with a Bellamy corner.
Rovers had the ball in the back of the net in the 35th minute when Leon Best got on the end of Morten Gamst Pedersen's cross but the celebrations were cut short by another offside flag.
Campbell then rattled the crossbar with a right-footed shot on the turn from 12 yards out. The Bluebirds made the breakthrough on 40 minutes.
Campbell rose unmarked to nod Bellamy's corner past Kean from close range to finally break the stubborn Rovers resistance.
Six minutes after half-time the visitors were forced into swapping their keeper after Kean was stretchered off. It meant a debut for Poland international Grzegorz Sandomierski.
Sandomierski was called upon to deny first Bellamy and then a fantastic effort from Kim Bo-kyung. But the Pole was eventually beaten with six minutes left by a fine individual goal from Mason who turned two defenders before drilling a low, hard shot into the back of the net.
And in added time Mason was fouled by Scott Dann and Whittingham's low penalty added gloss to their first win in four home games.