Eichel made it 1-0 at 10:28 of the first period, tipping in an Alec Martinez shot, and extended the lead to 2-0 at 1:26 of the second period after Seattle defenseman Jamie Oleksiak fell and lost the puck to Evgenii Dadonov, who found him alone in the slot.
It was Eichel's first multigoal game since Feb. 22, 2020, when he scored two goals against the Pittsburgh Penguins as a member of the Buffalo Sabres.
"Every game's competitive in the league, it doesn't matter where you're playing," Eichel said. "They have a lot of good players over there, so it's important, you have to take care of business every night. We know the position that we're in, but we can only control so much and just get two points every night."
Jonathan Marchessault scored, Dadonov and Chandler Stephenson each had two assists, and Logan Thompson made 26 saves for the Golden Knights (38-28-4), who won their fourth straight and moved one point ahead of the Dallas Stars for the second wild card in the Western Conference.
"Winning is fun, right?" Vegas coach Peter DeBoer said. "We won three in a row, and [now] four in a row tonight, that leads to that fun environment. And when you've lost four or five in a row, it's tough to recreate that. … We took care of business, and we knew we needed to because of the teams around us. We came in here and did what we need to do and you know, it's on to the next job."