Fleury, who was making his 10th consecutive start, got his 421st NHL win, two shy of tying Tony Esposito for ninth in League history.
"It was good to win. We came out strong. I think the guys played well," said Fleury, who got the start despite allowing five goals in a 5-1 loss to the Los Angeles Kings on Saturday. "... It was not a good game for anyone on the team and it was good that we got to put it behind us quickly, came home and got a good win against a good team."
WATCH: [All Stars vs. Golden Knights highlights]
Ryan Carpenter, William Karlsson, Alex Tuch and Reilly Smith scored for Vegas (17-14-1), which has won eight of its past 10 games.
Martin Hanzal scored, Esa Lindell had a goal and an assist, and Miro Heiskanen had two assists for Dallas (16-11-3), which had won four straight. Ben Bishop made 24 saves.
"I'm a little concerned right now because our energy and emotion the last two games hasn't been there," Stars coach Jim Montgomery said. "We were consistently playing with emotion and energy and a lot of competitiveness, which comes with those two qualities, and in the last two games, we haven't had that."
Hanzal, who was playing in his second game this season following spinal fusion surgery in March, gave the Stars a 1-0 lead with a deflection on the power play at 6:29 of the first period. It was his first goal since Feb. 5.
Carpenter scored his first goal of the season on a rebound at the left post to tie it 1-1 at 16:12.