It was the Mavericks' 13th straight win over the Lakers, who have lost six of their last seven games this season.
The game was close for 10 minutes, with Dallas leading 23-22 before the Mavericks scored the next 15 straight to blow the game open. Nowitzki had seven during the run.
The Mavericks led 67-33 at the half and never looked back.
Lou Williams led the Lakers with 15.
The Mavericks both scored the most points and allowed the fewest in a half and a game this season. The 34-point halftime lead was the third-largest in franchise history.
The Lakers scored their fewest points in a quarter, a first half and a game.
Lakers scored 73 points, lost by 49 (worst loss in franchise history) on 11th anniversary of Kobe Bryant's 81-point game pic.twitter.com/L3KbG3808L— ESPN Stats & Info (@ESPNStatsInfo) January 22, 2017
All 11 Mavericks who played in the first half scored and had at least one rebound.
Dallas' Seth Curry scored 14 points, including seven straight in the first quarter for a 13-6 lead.
The game was tied 20-20 before Devin Harris made a 3-point shot with 2:46 remaining for a lead that Dallas never lost.
Lakers: They played without D'Angelo Russell, second on the team at 14.3 points per game. An MRI taken Saturday showed a mildly sprained right MCL and strained right calf.
Mavericks: J.J. Barea missed his 26th game this season because of a strained left calf. Coach Rick Carlisle said he didn't expect Barea back until after the All-Star break (Feb. 24 at the earliest). Andrew Bogut (strained right hamstring) could return this week, but would need a day of practice, according to Carlisle.
Lakers: Travel to Portland for the second game of a three-game trip on Wednesday.
Mavericks: Complete a three-game homestand on Wednesday against New York.