The Golden Knights (46-22-6), who visit the San Jose Sharks on Thursday, clinched when the Nashville Predators lost 2-0 to the Pittsburgh Penguins.
Vegas is first in the Pacific Division, one point ahead of the second-place Edmonton Oilers.
The Golden Knights did not qualify for the playoffs last season. They reached the 2018 Stanley Cup Final, their first season in the NHL.
Vegas is led by forwards Jack Eichel (59 points), Chandler Stephenson (56) and Jonathan Marchessault (51).
Logan Thompson is 21-13-3 with a 2.65 goals-against average, .915 save percentage and two shutouts in 37 games (36 starts). Jonathan Quick is 5-2-0 with a 3.53 GAA and .896 save percentage in eight games (seven starts) since being acquired from the Columbus Blue Jackets on March 2.