Blackburn slowly established a foothold in the game, with Matt Derbyshire trying his luck from range, but Wigan goalkeeper Chris Kirkland got through the first half-hour without being seriously tested.
Valencia nearly scored his second and Wigan's third shortly before half-time when he flashed a half-volley just over from Maynor Figueroa's long throw.
Brett Emerton had a shot blocked and Christopher Samba headed over from the resulting corner as Rovers tried to stem the tide, but these were just temporary blips as Wigan continued pummelling the visitors' goal.
I'll keep fighting - Ince
Heskey and Amr Zaki could both have added to the lead but the best chance for a third fell to Cattermole, as he headed against the bar from a delightfully lofted Valencia cross.
Dunn, who has not played since picking up an Achilles injury in August gave Blackburn more purpose following his half-time introduction.
And they came close to pulling a goal back when Emerton's free-kick was deflected towards his own goal by Taylor, but Kirkland did superbly to turn it behind.
Emerton and Dunn did their best to drag their team back into the game, but Blackburn's chances were ended by a sucker punch with 14 minutes left.
Inevitably, Valencia was the creator as he fired in a cross from the right, which took a deflection off Andre Ooijer, and Taylor wisely stood back to let the ball go into the path of Cattermole, who buried it.
Wigan manager Steve Bruce:
"Antonio Valencia in the first half hour was on fire. We had to keep giving him the ball - he proved what a fantastic player he is.
"A good start was what we wanted against a team suffering on confidence but I thought they played decently.
"It's a small squad but with a bit of quality, I'd rather have that than one that's big but not good enough".
Blackburn manager Paul Ince on his future:
"It doesn't matter about Paul Ince, it matters about these players. What will be will be.
"I'm disappointed for my players and the fans who have come in abundance and we've let them down, we'll have to take stock and start again on Monday.
"I don't care who's in charge, me or Alex Ferguson, giving away a two goal start will always be trouble."
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