Chances were scarce in the opening stages with El-Hadji Diouf's weak header comfortably gathered by Duke and a leaden first touch from Geovanni sent the ball squirting through to Paul Robinson.
On 34 minutes Pedersen manoeuvred his way through a clutch of defenders on the edge of the box and his deflected shot bobbled across the goal towards the far post.
Duke got to it fractionally before Roque Santa Cruz, but the keeper allowed it to slip his grasp and the Paraguayan striker laid it back to Warnock who sidefooted home first time into the empty net.
Win is massive for Blackburn - Allardyce
A minute later, a long clearance bounced through to Pedersen, Warnock galloped onto his neat lay-off, past Nathan Doyle and squared low to Andrews for the second.
With the Hull defence rocking, Santa Cruz came close to adding his name to the scoresheet as a succession of dangerous crosses sailed across the six-yard box, narrowly clearing his forehead.
In the final minute of the half, Michael Turner clattered into Robinson in pursuit of a loose ball, winding the keeper, adding his name to the referee's book and ensuring Jason Brown would come off the Rovers' bench at half-time.
Phil Brown's removal of the lively Geovanni after the break upset both the playmaker and large sections of the crowd and their mood worsened as Marney responded to a heavy challenge by kicking out at Pedersen under Atkinson's nose.
Geovanni will be dealt with - Brown
The Norwegian received a booking for his involvement which proved crucial as his stray boot, coming through late and high on Kamil Zayatte, saw him dispatched down the tunnel soon after.
Mendy then stubbed over a cross which Ashbee volleyed into the ground and over Brown's despairing dive to ensure the KC Stadium had a tense final 10 minutes.
But Hull could not carve out any clear-cut chances despite the weight of numbers committed to the Blackburn box and were restricted to long-range efforts from Turner and substitute Nick Barmby.
Hull manager Phil Brown:
"It is the biggest test of character of my career, in terms of a manager, and it probably is for the players.
"We have got to try to play above ourselves in the last 11 games, it is as simple as that.
"If we minimise mistakes between now and the end of the season there is a possibility we will be OK but it has to happen now."
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