Mittelstadt put the Sabres ahead 1-0 2:36 into the first period on a one-timer in the left face-off circle off a pass from Jimmy Vesey. Mittelstadt stole the puck from Kings defenseman Sean Walker in the neutral zone, leading to his first goal of the season.
Sheary made it 2-0 at 5:20 on a one-timer from the top of the right circle off a pass from Mittelstadt on the rush. Sheary missed the previous four games because of an upper-body injury.
"We were pretty due," Mittelstadt said of his line with Sheary and Vesey. "The last few games, we had quite a few chances, especially the last couple even though [Sheary] was out. But played with him enough that it's pretty easy to pick up where we left off. I think we've done a lot of good things, and it was good to see a few go in."
Mittelstadt scored on the power play 2:32 into the second period to make it 3-0.
It was Mittelstadt's first NHL multigoal game, his first game with three points, and his fourth multipoint game in three NHL seasons.
Sabres coach Ralph Krueger felt they became too aggressive after the third goal at the expense of their defensive responsibilities, allowing the Kings to get 36 shots in the second and third periods.
"We were trying to get the 4-0 (goal) at times in the second period, and (the team is) still learning how to manage games like this," Krueger said. "We are a group that has so much to learn, and tomorrow's going to be another day of learning. I think today what happened was guys were excited by the way the game started for us."
The Kings had a 5-on-3 power play for 1:32 late in the second and to start the third. The Sabres allowed one shot during the two-man advantage, and one second after the first penalty ended, Hutton made the save on a tipped shot by Jeff Carter at close range at 1:12 of the third.
"Just when it looked like they might sneak back in the game, he made a big save for us, and that kind of kept us going I think," Mittelstadt said.