Leo Carlsson had a goal and an assist, and Beckett Sennecke, Alex Killorn and Jeff Malott also scored for the Ducks in their season opener. Lukas Dostal made 27 saves.
Shea Theodore, Tomas Hertl, and Braedan Bowman scored, and Jack Eichel had two assists for the Golden Knights (1-1-0). Carter Hart made 16 saves.
Vegas opened the season with a 5-2 win against the Chicago Blackhawks on Tuesday.
Sennecke gave the Ducks 1-0 lead at 19:52 of the first period. Shortly after a Golden Knights power play ended, Carlsson sent a lead pass to Sennecke, who got behind the defense and lifted a shot past Hart on a breakaway.
Killorn redirected a Noah Warren point shot at the edge of the right face-off circle at 1:33 of the second period to push the lead to 2-0. Warren's assist was his first NHL point in his first NHL game.
Malott extended it to 3-0 at 2:28 just 55 seconds later. Tim Washe deflected Jackson LaComb's shot from the left point, and the puck then deflected off Malott's right skate from the low slot through the five-hole.
Carlsson pushed the lead to 4-0 at 7:03. Hart made the initial save on a A.J. Greer shot, but was caught out of position allowing Carlsson to put the rebound into an open net.
Theodore cut the deficit to 4-1 at 4:38 of the third period, beating Dostal at the far post from the right dot. The Ducks challenged the play for offside, but the goal was upheld after a video review.
Hertl made it 4-2 on the ensuing power play at 6:07, finishing in close by banking the puck in off the right post.
Bowman scored at 17:10 for the 4-3 final after finding a loose puck in the low slot during a scramble and putting it past Dostal.
