Their cause was not helped by having veteran goalkeeper James Walker sent off in the 33rd minute for handling the ball just outside the area.
The Saddlers did not have another keeper on the bench so full-back Lee Beevers had to go in goal and the first thing he was required to do was pick the ball out of the net when Dons skipper Dean Lewington swept a perfect free-kick into the top corner after 35 minutes.
Dons, who had won only one of their previous nine games, added a second goal just before half time. Former Walsall striker Jabo Ibehre stabbed the ball home after Beevers had blocked a shot from Daniel Powell.
At half-time Walsall manager Dean Smith, who had been upset earlier in the game when he felt the referee missed an elbow on striker Jon Macken, was sent to the stands.
In the second half Walsall’s 10 men battled bravely and substitute Claude Gnakpa was unlucky in the 62nd minute when his shot hit both posts before rebounding to safety.