Beckett Sennecke, Leo Carlsson and Jansen Harkins scored for the Ducks, who are the No. 3 seed from the Pacific.
Mark Stone scored the lone goal, and Carter Hart made 25 saves for the Golden Knights, who are the No. 1 seed from the Pacific Division.
Anaheim evened the best-of-7 series 1-1. Game 3 is at Honda Center on Friday (9:30 p.m. ET; TNT, truTV, HBO MAX, SN, SN360, TVAS).
Sennecke gave the Ducks a 1-0 lead at 11:23 of the second period. Jeffrey Viel collected the puck behind the net and fed a pass in front to Sennecke, who lifted a shot past Hart's glove.
Carlsson made it 2-0 at 6:36 of the third period, chipping Troy Terry's backhanded pass in off the glove of Hart from in front.
Harkins pushed the lead to 3-0 with an empty-net goal at 16:30. It was his first playoff goal since Aug. 30, 2020, when he was a member of the Winnipeg Jets.
Stone redirected a Jack Eichel shot under Dostal's right arm while on the power play at 19:54 for the 3-1 final.
The Ducks finished 0-for-5 on the power play, including a 5-on-3 for 1:37 in the first period, and are 0-for-9 in the series.
