Midfielder Luke Chadwick scored twice to book MK Dons a place in the third round of the League Cup at Blackburn's expense.
Chadwick calmly slotted home Jon Otsemobor's cutback to score his first just after half-time.
And he made it 2-0 when he tapped in after Daniel Powell's shot had been spilled by Rovers keeper Jake Kean.
David Goodwillie headed in Fabio Nunes's cross but it proved just a consolation for Steve Keane's side.
Blackburn were lacklustre throughout the game, with MK Dons deserving of their victory.
The home side controlled the first half and Blackburn goalkeeper Kean produced good saves to deny Powell and Chadwick, while Charlie MacDonald clipped an effort just wide.
Rovers' Edinho Junior had a low shot cleared off the goal-line by Shaun Williams in the visitors' best chance of the first half.
Ultimately, Chadwick's double in the second half gave League One side MK Dons a lead they never looked like throwing away, even when Championship side Blackburn scored with eight minutes remaining.
MK Dons boss Karl Robinson: "It was comfortable, I'm very pleased because it was a very professional performance.
"We looked very accomplished and we move on from here with tremendous mental strength and belief in ourselves.
"The first five minutes they started OK but once our two midfield players got to grips with it we were the better side.
"We looked good but I just don't want to go over the top because it's a cup game and we need to move on from here very quickly."
Blackburn boss Steve Kean: "I never thought we played well, I felt that we were a little bit predictable in the end.
"The ball wasn't sticking from the front and it was difficult for young Edinho because he's not got the physical presence yet, but he was working his socks off.
"I think we could have helped him a bit more by, when the ball was going up to him, giving him an angle that he could get onto that wasn't a straight one.
"Obviously we made a few changes because the older players in the squad, by the time we get to Saturday, if they had played it would have been five games in 14 days.
"So it was an opportunity for some players who have not played as many minutes as others to get the chance and it was up to them to take it."
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Live Text Commentary
Full Time The final whistle goes and the game is over.90:00 +2:22 Substitution
Substitution Jabo Ibehre replaces Dean Bowditch.90:00 +1:32
Foul by James O'Shea on Simon Vukcevic, free kick awarded. Free kick taken by Jake Kean.90:00 +0:38
Dean Bowditch takes the chance to get an effort at goal. Comfortable save by Jake Kean.89:51
Unfair challenge on Dean Bowditch by Paulo Jorge results in a free kick. Jon Otsemobor restarts play with the free kick.88:52
The referee blows for offside against Fabio Nunes. David Martin takes the indirect free kick.87:31
Daniel Powell gives away a free kick for an unfair challenge on Bradley Orr. Jake Kean restarts play with the free kick.86:55
Outswinging corner taken right-footed by Dean Bowditch, Shaun Williams takes a shot. Clearance made by Bradley Orr.86:32
Daniel Powell takes a shot. Grant Hanley gets a block in.85:36
James O'Shea fouled by Mauro Formica, the ref awards a free kick. David Martin restarts play with the free kick.82:09
Fabio Nunes provided the assist for the goal.82:09 Goal scored
Goal! - David Goodwillie - MK Dons 2 - 1 Blackburn David Goodwillie grabs a headed goal from inside the six-yard box. Milton Keynes Dons 2-1 Blackburn.82:01
Fabio Nunes delivers the ball,79:43
Darren Potter gives away a free kick for an unfair challenge on Simon Vukcevic. Jason Lowe takes the direct free kick.79:20
Simon Vukcevic fouled by Stephen Gleeson, the ref awards a free kick. Simon Vukcevic restarts play with the free kick.77:42
Right-footed shot by Mauro Formica went harmlessly over the bar.76:09
Free kick taken by David Martin.76:09 Substitution
Substitution James O'Shea joins the action as a substitute, replacing Luke Chadwick.76:09
Free kick awarded for a foul by David Goodwillie on Dean Bowditch.75:09
Dean Bowditch has a shot on goal from outside the area which misses right.
Substitution (Milton Keynes Dons) makes a substitution, with Ryan Lowe coming on for Charlie MacDonald.72:41
Inswinging corner taken by Simon Vukcevic from the right by-line, Grant Hanley has a headed effort at goal from deep inside the area missing to the right of the target.72:31
The ball is crossed by Markus Olsson, Gary MacKenzie makes a clearance.70:16
Unfair challenge on Daniel Powell by Grant Hanley results in a free kick. Daniel Powell restarts play with the free kick.68:43 Substitution
Substitution Mauro Formica replaces Ruben Rochina.67:53
The assist for the goal came from Daniel Powell.67:53 Goal scored
Goal! - Luke Chadwick - MK Dons 2 - 0 Blackburn Luke Chadwick gets on the score sheet with a goal from inside the box low into the middle of the goal. Milton Keynes Dons 2-0 Blackburn.66:43
Shot by Daniel Powell. Save by Jake Kean.63:45
Shot on goal by David Goodwillie from long range goes harmlessly over the target.62:07
Short corner worked by Dean Bowditch.61:58
Daniel Powell crosses the ball, Grant Hanley makes a clearance.61:11
Inswinging corner taken right-footed by Dean Bowditch, Grant Hanley makes a clearance.60:45
Daniel Powell has an effort at goal. Blocked by Bradley Orr.59:47
Ruben Rochina gives away a free kick for an unfair challenge on Dean Bowditch. Darren Potter takes the free kick.59:26
Centre by Fabio Nunes.57:30 Substitution
Substitution Jason Lowe on for Dickson Etuhu.57:30 Substitution
Substitution Edinho Junior leaves the field to be replaced by David Goodwillie.51:49
The assist for the goal came from Jon Otsemobor.51:49 Goal scored
Goal! - Luke Chadwick - MK Dons 1 - 0 Blackburn A goal is scored by Luke Chadwick from deep inside the penalty area to the bottom right corner of the goal. Milton Keynes Dons 1-0 Blackburn.50:29
The referee blows for offside. Free kick taken by Jake Kean.50:00
The official flags Charlie MacDonald offside. Jake Kean takes the indirect free kick.49:39
Dean Bowditch takes the chance to get an effort at goal. Charlie MacDonald gets a block in.46:18
The assistant referee signals for offside against Daniel Powell. Indirect free kick taken by Jake Kean.45:01
The referee starts the second half.45:00 +1:09 Half time
Half Time The match has reached half-time.45:00 +0:12
The ball is crossed by Markus Olsson, clearance made by Gary MacKenzie.42:56
The assistant referee signals for offside against Charlie MacDonald. Jake Kean takes the indirect free kick.39:05
Simon Vukcevic takes a inswinging corner.38:31
Unfair challenge on Edinho Junior by Gary MacKenzie results in a free kick. Fabio Nunes takes the direct free kick.37:38
Dean Bowditch takes the inswinging corner, free kick awarded for a foul by Charlie MacDonald on Jake Kean. Jake Kean takes the free kick.36:34
The referee blows for offside against Charlie MacDonald. Jake Kean restarts play with the free kick.33:42
Corner taken by Dean Bowditch.33:29
Dean Bowditch takes a shot. Jake Kean makes a save.31:46
Shot from just outside the box by Ruben Rochina misses to the left of the goal.29:10
Inswinging corner taken by Simon Vukcevic from the right by-line.28:56
A cross is delivered by Markus Olsson, clearance made by Gary MacKenzie.25:11
Stephen Gleeson has an effort at goal from just outside the box which goes wide of the right-hand upright.23:52
Effort from 30 yards by Ruben Rochina.23:29
Shaun Williams gives away a free kick for an unfair challenge on Edinho Junior. Direct free kick taken by Simon Vukcevic.22:37
Outswinging corner taken right-footed by Dean Bowditch from the right by-line to the near post, clearance made by Bradley Orr.22:08
Free kick awarded for an unfair challenge on Ruben Rochina by Darren Potter. Ruben Rochina takes the direct free kick.19:28
Outswinging corner taken right-footed by Dean Bowditch from the right by-line to the near post, Bradley Orr manages to make a clearance.18:11
Effort on goal by Luke Chadwick from just inside the penalty area goes over the target.15:07
Ruben Rochina takes the chance to get an effort at goal. Save made by David Martin.13:51
Simon Vukcevic takes a shot. Comfortable save by David Martin.12:44
Centre by Daniel Powell.12:13
Corner taken right-footed by Dean Bowditch from the right by-line, Grant Hanley makes a clearance.11:49
Daniel Powell takes a shot. Grant Hanley gets a block in.9:09
The ball is sent over by Daniel Powell, Effort on goal by Charlie MacDonald from inside the box misses to the right of the target.6:53
Free kick awarded for an unfair challenge on Bradley Orr by Dean Bowditch. Direct free kick taken by Scott Dann.6:30
The ball is sent over by Bradley Orr.5:35
The ball is delivered by Simon Vukcevic.4:19
Simon Vukcevic delivers the ball.3:31
Shot from 12 yards from Ruben Rochina. Clearance by Shaun Williams.1:23
Jon Otsemobor concedes a free kick for a foul on Fabio Nunes. Free kick taken by Markus Olsson.0:37
Daniel Powell takes a shot. Jake Kean makes a fantastic save.0:00
The referee gets the match started.
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