Dons defender Dean Lewington had to receive stitches after clashing heads with a Rochdale player while challenging for the ball, but he was fine to continue after a few minutes on the sideline.
Dean Bowditch then got MK Dons in front with a fine low drive from 15 yards out.
The second half was a slow affair, broken up by the number of substitutions, but Reuben Noble-Lazarus equalised for Dale after 65 minutes, his shot from close range ending up in the back of the net.
Donal McDermott then put Rochdale in front with a smashing shot from 25 yards out six minutes from full time.
Rochdale's first league game of the season will be at home to Peterborough United on August 8.