The Nuggets had a nine-point halftime lead before outscoring the Suns by 14 in the third quarter to put the game away.
Nene had 22 points and Lawson grabbed 11 rebounds to go with his 20 points. Wes Chandler added 16 points in Denver's seventh victory in nine games.
The Nuggets are three games behind Oklahoma City for the lead in the Northwest Division.
Marcin Gortat led Phoenix with 14 points and 16 rebounds off the bench.
Denver shot 51 percent from the field and came up with 16 steals.