Luke Hyam put the Blues ahead in the fourth minute with his first goal of the season, but former Blue Jordan Rhodes struck back on the half hour to level.
Town boss Mick McCarthy made four changes to the team which beat Charlton on Saturday. Skipper Carlos Edwards came in at right midfield, Hyam into the centre, Stephen Hunt made his full debut on the left and Frank Nouble joined David McGoldrick up front.
Paul Anderson, Ryan Tunnicliffe, Jay Tabb and Daryl Murphy all dropped to the bench, while Paul Taylor again missed out due to his shoulder injury.
Blackburn included ex-Blue Rhodes and former loanee DJ Campbell up front from the start with both players applauded by the home support when their names were announced.
Campbell struck the game’s first shot in the second minute, Blues keeper Dean Gerken saving his sharp strike on the turn and Hyam reacting quickest to stab behind.
But as in the games against Leicester and Charlton, Town would take an early lead, Hyam netting his first goal of the season and only the second of his career in the fourth minute.
Cole Skuse looped into the box from deep and Tommy Spurr under pressure from McGoldrick headed to Hyam on the edge of the area. The ball initially got caught under the midfielder’s feet but having set himself he struck a low shot to Rovers keeper Jake Kean’s right and into the net.
The Blues enjoyed most of the early possession but the visitors might have got back on terms in the 14th minute when Josh King broke away down the Blackburn left. The Norwegian international’s touch let him down and Tommy Smith was able to get across to make a superb saving challenge and Gerken grabbed the loose ball.
At the other end, McGoldrick hit a shot on the turn, which only just flew over Kean’s bar, then a minute later Hunt brought the ball forward on the left before crossing towards Edwards, but the Town captain couldn’t control his header.
After Skuse had failed to find McGoldrick with a 25th minute pass as the Blues broke, Campbell was booked for a foul on his former team-mate Aaron Cresswell. Following the resultant freekick, Smith laid the ball off to Edwards, who fired not far wide from the 18-yard line.
Blackburn levelled on the half hour and inevitably Rhodes was the man on target. Grant Hanley played a long ball down the middle which ought to easily have been defended, but the former Blues striker got to the ball ahead of the Town defence, went past the advancing and stranded Gerken and stroked his 11th goal of the season into the empty net with the Town keeper claiming offside.
The striker’s corner flag punching celebration in front of a Blues section of the Cobbold Stand failed to impress the home support with his subsequent contributions receiving boos.
Nouble sent across a dangerous low ball in the 34th minute but behind McGoldrick and ahead of Hunt. However, the visitors had had looked the more threatening side having equalised with the Blues backline the busier of the two defences.
As the half moved into its final minute Blackburn claimed a penalty when a clearance struck Hunt on the hand, however, referee Fred Graham waved away the protests for what would have been a very harsh spotkick.
Town were the side happiest to hear the half-time whistle, the visitors having been on top since netting their goal. The Blues had again started strongly and might have added to their lead before conceding what was a very poor goal.
From there, Blackburn were much the better side with Town giving the ball away all too easily and rarely threatening.
Town: Gerken, Chambers, Berra, Smith, Cresswell, Edwards, Hyam, Skuse, Hunt, McGoldrick, Nouble. Subs: Loach, Mings, Tunnicliffe, Tabb, Anderson, Graham, Murphy.
Blackburn: Kean, Kane, Dann, Hanley, Spurr, Cairney, Williamson, Lowe, King, Campbell, Rhodes. Subs: Eastwood, Kilgallon, Marshall, Rochina, Judge, Henley, Gestede. Referee: Fred Graham (Essex). Att: