Vladislav Namestnikov gave the Red Wings a 4-1 lead at 11:39 of the second period, banking the puck in off Brossoit's back.
"I thought the second period might have been our best stretch of hockey this year," Larkin said. "I thought we outworked them tonight. Every guy worked hard, and Thomas Greiss was incredible."
Marchessault made it 4-2 at 4:25 of the third with a shot from the slot, but Greiss made 19 saves in the period.
Bertuzzi scored an empty-net goal with 11 seconds left for the 5-2 final. It was his ninth goal of the season.
"He's a good goalie, he's going to stop anything he can see," Vegas defenseman Shea Theodore said of Greiss. "We needed to do a better job of getting in front of him and taking away his eyes."
NOTES: Red Wings forward Sam Gagner, and defensemen Nick Leddy and Filip Hronek each had two assists. … Roy had seven shots on goal, and Marchessault had five. … Detroit hadn't scored two power-play goals in the same game since March 16, a 4-2 win against the Carolina Hurricanes. … Larkin returned after missing three games with a family issue. … Red Wings defenseman Gustav Lindstrom played 15:07 after missing six games because of a lower-body injury. … Detroit defenseman Danny DeKeyser played his 500th NHL game.