Kevin Seraphin added 18 points and Wall and Trevor Ariza each added 14 points for the Wizards, who picked up just their second win away from home this season. They entered a league-worst 1-16 on the road.
Wall also had 12 assists. Nene had seven points for Washington in his return to Denver, where he played for nearly 10 years before being sent to Washington last March as part of a three-team trade.
Lawson scored 29 points to lead the Nuggets, who lost at home for just the third time in 18 games. He had made 10 consecutive shots from the floor before Wall rejected his layup in the final moments.
Corey Brewer and Andre Miller each added 17 points for the Nuggets, whose home-winning streak ended at five games.