The win at the American Airlines Arena was Miami's second over the NBA champion Mavericks since losing the Finals series 4-2. The Heat beat Dallas in their season-opening game on Christmas Day 105-94.
"Hopefully, this will give us a little bit of momentum," Heat forward Chris Bosh said ahead of the team's two-game road trip against Toronto and Boston.
"This is a big road trip for us. We're looking to turn the corner. We know we're a good road team as well."
Miami (36-13) lost four of their last six games on the road but took command of their home court with an 11-4 run in the final minutes of the second quarter to seize a 60-53 lead at halftime.
The Heat raised their game again in the final quarter, outscoring Dallas 26-13 to dominate the more defensive second half.
"You have to give them credit," Mavericks forward Dirk Nowitzki said.
"They stepped up their pressure on both ends of the floor. In the first half, everything came a little too easy for us. We got some good looks, got some rolls, had everything going. Then they really picked up their pressure and we didn't have many good looks."
Miami had six players score in double digits led by LeBron James and Bosh who scored 19 points and had nine rebounds each.
Dwyane Wade and Udonis Haslem added 16 points each, while Mario Chalmers added 12 and Norris Cole 10.
"This was a great box score to look at," Heat coach Erik Spoelstra said. "Nobody scored over 20, but we had a lot of different contributions."
Nowitzki led the visitors (29-23) with 25 points despite scoring just one field goal on nine attempts in the second half.
Lamar Odom scored 12 points off the bench.
