The eight goals are the most the Golden Knights have scored in a game in their two NHL seasons.
Shea Theodore and Cody Eakin each had two goals and an assist for Vegas (13-12-1), which opened a three-game road trip following a 4-1-0 homestand. Marc-Andre Fleury made 21 saves for his fifth straight win, including shutouts in his previous two games.
WATCH: [All Golden Knights vs. Blackhawks highlights]
"I thought we controlled the game in the second and third," Fleury said. "I thought we had the puck, we didn't give them many shots. I thought our team deserved some credit for scoring some goals and for playing well."
Forward Dylan Strome scored in his debut with the Blackhawks (9-11-5), who have allowed at least four goals each of their past four games (1-3-0). Corey Crawford made 24 saves on 30 shots before being relieved at the start of the third period by Cam Ward, who made 11 saves.
"I think you put yourselves in a hole and it's hard to score in this league," Strome said. "Sometimes if you're opening up chances because you got down 3-0, it ends up in the back of your net, and it did tonight and we didn't help out our goalie enough."
Strome played center on a line with Alex DeBrincat and Patrick Kane.
"It's pretty easy to play with those two guys," Strome said. "Alex, we're finding each other out there a bunch of times. Obviously, [Kane], you just have to get open and he'll find you. So he creates a lot of opportunity every time he touches the puck. It was fun."
Daniel Carr gave Vegas a 1-0 lead at 2:10 of the first period with his first goal of the season in his third game since signing with the Golden Knights as a free agent July 1.