Olsson's crucial winner
Blackburn got the win they wanted following the untimely death of supporter John Taylor at the weekend. They got the vital goal after 16 minutes when Martin Olsson's effort from the byline was deflected by goalkeeper Boaz Myhill.
After going a goal down, Hull went a man down when George Boateng was sent off and they have yet to win on the road in the league this season.
Blackburn boss Sam Allardyce made three changes to his side for the Premier League game against Hull at Ewood Park. Michel Salgado, El-Hadji Diouf and Keith Andrews all returned to the team following the defeat by Stoke.
Hull were looking to build on the victory against Manchester City with manager Phil Brown naming an unchanged team.
Blackburn opened the scoring in the 16th minute after Diouf set Olsson scampering away down the left. The full-back's shot from the byline took a deflection off Myhill and went into net to give Blackburn the start they were hoping for.
Hull's troubles increased in the 39th minute when they were reduced to 10 men, Boateng red-carded after needing treatment following an aerial challenge on Morten Gamst Pedersen in the middle of the park.
Blackburn came close to extending their lead in the 43rd minute after an inswinging corner from Diouf. Nelsen was about to pounce at the back post, but Myhill was able to touch the ball to safety, as Sam Allardyce's men went on to record their first win in four games.