Lawson made 3-of-4 of his 3-point attempts and added eight assists. Denver won on the road for the first time in four tries this season.
Kenneth Faried added 16 points and 16 rebounds for Denver while Corey Brewer delivered 14 off the bench.
Houston shot just 36 percent from the field and lost its second straight after opening the campaign with two consecutive wins.
The Rockets were led by Carlos Delfino with 19 points and Patrick Patterson had 18. James Harden, who went over the 40-point mark in his first two games and was averaging a league-best 35.3 per contest, scored 15.