Lawson was injured in the Nuggets' 126-109 loss to the Detroit Pistons on Saturday night. Originally called a left lower-back strain, a postgame X-ray revealed the break.
"You could see it take the wind out of us when Ty came out of the game," Denver coach Brian Shaw said. "He's our floor leader and he's the one who controls the pace and the tempo of the game. He's also the best guy we have to stay in front of (Brandon) Jennings."
Lawson played 19 minutes Saturday night and finished with six points, seven assists and three rebounds.
In his fourth season, Lawson leads the Nuggets in points (18.3), assists (8.8) and steals (1.5) per game.
Information from The Associated Press was used in this report.