Crystal Palace ended 2011 with a win thanks to Jermaine Easter's first-half goal at the New Den.
The victory, which is Palace's sixth away from home this season, sees them edge nearer to the playoffs heading into the New Year.
After an even start, forward Easter slotted home Darren Ambrose's square pass midway through the opening period to score what turned out to be the only goal.
Millwall tried to impose themselves as the game went on with Hamer Bouazza orchestrating much of the good Lions' play. They were unable however to find a way past Lewis Price in the Eagles goal.
Kenny Jackett's men will look to bounce back when they travel to fellow strugglers Bristol City on Tuesday while Palace begin 2012 by welcoming Leicester to Selhurst Park.
