Both sides were in desperate need of the three points for different reasons and from the outset it was clear neither would be happy with a draw.
The visitors came closest to opening the scoring when Craig Davies found Lloyd Owusu in the box but Dons keeper Willy Gueret pulled off a superb double save from close range.
But it was the hosts who were dominating most of the early possession and after a couple of half chances falling to Mark Wright and Jason Puncheon in between a succession of corners, the Dons eventually made the breakthrough.
Previously out of favour Canada international Ali Gerba was the man to get the goal on the half hour as he picked up a Sam Baldock pass on the edge of the penalty area and found the bottom corner of Michels Kuipers' goal.
The goal took the wind out of the Seagulls' sails as they simply tried to keep the deficit at just one going into the break.
But as half-time approached, their frail defence was breeched for a second time when Puncheon headed home Mark Wright's cross on 40 minutes.
Brighton offered brief glimpses of an attacking threat but the game was as good as over at the interval and the previously boisterous travelling contingent knew it.
The second half was a largely mundane affair as Brighton looked hopeless going forward and the Dons simply took their foot of the pedal.
Owusu remained the Seagulls' biggest threat and he set up Dean Cox to shoot just wide in a rare Brighton venture into the Dons half.
At the other end, Puncheon was proving a constant thorn in Brighton's defence until he was given a rest.
After that the home side had several chances to increase their lead, the best coming to Gerba with a superb turn and shot but Kuipers was equal to it.
The Brighton shot-stopper continued to keep the score respectable for his side in the closing stages, but that wasn't enough to stop some of the 2,000 plus away fans from venting their frustrations.
The result compounds Brighton's relegation fears, but after just one win seven it was exactly for the doctor ordered for the Dons.