Birthday boy Daryl Murphy scored twice to put Ipswich within a point of the Championship play-off places.
Murphy broke the deadlock from the penalty spot in the 67th minute after Luke Chambers had been fouled.
The striker marked his 33rd birthday by making the game safe by firing home his 10th goal of the season from 18 yards.
Mid-table Blackburn had started brightly and Simeon Jackson and Shane Duffy both forced Town goalkeeper Bartosz Bialkowski into early saves.
The victory, Ipswich’s third in five games, leaves Mick McCarthy’s side level on points with seventh-placed Cardiff and both sides are hot on the heels of Sheffield Wednesday with nine games remaining.
Blackburn remain 16th – seven points above revitalised Rotherham – after their third defeat in four matches.
Despite Rovers’ bright start, they could not build on it and once they fell behind they never looked like getting back into the match.
Blackburn goalkeeper Jason Steele denied Brett Pitman in the first half and went the right way for Murphy’s penalty but had no chance of saving his second.
Ipswich Town manager Mick McCarthy:
“I thought it was a great victory. It was a tough, hard-fought match which I thought they had the better of at the start.
“But we slowly got into the match and we were deserved winners in the end.
“We have been here before – sometimes you have to stick with it, win the scrap, make sure you don’t concede and then you always have a chance.”
“Murph has had it tough this year with a few knocks and niggles. But I thought his performance tonight was excellent and his second goal was outstanding.”
Blackburn Rovers manager Paul Lambert:
“We have played well of late so I am disappointed with tonight.
“That was our 10th match in 30-odd days so I had to make changes as some of the lads were running on empty.
“A lot of our fans came to watch and they deserved better than what we showed in the second half – we were rotten.
“I have no complaints about the penalty, it was a stone-waller, but I expected better when we went a goal behind.”