Kennedy netted the decisive goal in the 85th minute to settle a pulsating clash at stadium:mk and lift the Bantams up to sixth in the table.
Shaun Williams curled an early free-kick against the crossbar for the Dons before Nahki Wells put Bradford ahead after 22 minutes, neatly steering home Garry Thompson’s low cross for his 13th goal of the season.
Daniel Powell was then denied an equaliser when one-on-one with goalkeeper Jon McLaughlin before Patrick Bamford did bring the Dons level in the 36th minute, racing clear onto Darren Potter’s pass to poke the ball past the keeper – also for his 13th goal of the season.
But Kyel Reid restored Bradford’s lead two minutes before the break when his 30-yard cross-shot looped over McLoughlin and inside the far post.
Wells almost extended the lead when his curling free-kick hit the post but he then tripped Dele Alli in the box, allowing Williams to equalise from the penalty spot after 72 minutes.
However, Kennedy won it for the visitors five minutes from the end when he slid in James Meredith’s low cross at the far post.