The game, on the whole, was a scrappy affair with the Blades' lead rarely threatened by the Dons, who saw their fading play-off hopes take another blow.
United took the lead midway through the first half when a good throughball by Conor Coady sent Scougall away one-on-one, with the Scot finishing calmly into the bottom corner.
The Blades almost doubled their advantage early in the second half when Jose Baxter's scruffy effort was cleared off the goal-line by Jordan Spence.
Substitute Ben Davies then had a free-kick deflected just wide for the visitors before MK Dons goalkeeper David Martin made a good save with his legs to deny Baxter.
Sanmi Odelusi sent a flying header from Ryan Hall's deep cross over the crossbar as the hosts plugged away for an equaliser which never arrived, leaving them still six points off the top six.