Schmid, who earned his second shutout of the season, played three seasons in New Jersey before being traded to Vegas on June 29, 2024, along with forward Alexander Holtz, in exchange for forward Paul Cotter and a third-round pick in the 2025 NHL Draft (forward Mason Moe).
Shea Theodore, Tomas Hertl and Ivan Barbashev each scored, and Jack Eichel had two assists for the Golden Knights (13-6-8), who won their third straight after losing their previous four.
Jacob Markstrom made 22 saves for the Devils (16-11-1), who have lost four straight at home and seven of their past 10 overall (3-7-0). New Jersey, who lost 3-0 against the Dallas Stars on Wednesday, was shut out in consecutive games at home for the first time since December 2008 (Dec. 23-26).
The Devils were in first place in the Metropolitan Division on Nov. 30. They are now fifth.
The Devils appeared to take a 1-0 lead 8:45 into the first period when Nico Hischier deflected in a shot from the slot, but the Golden Knights successfully challenged the play for offside when Timo Meier preceded the puck into the zone three seconds earlier.
Theodore gave Vegas a 1-0 lead at 19:47 of the first period on a snap shot from the right face-off circle that Markstrom missed to the long side.
Schmid made 11 saves in the second period. He denied Hischier off a 2-on-1 rush with Meier just 41 seconds into the second period.
Hertl pushed it to 2-0 with a power-play goal on a redirection from the high slot at 15:36 of the third period.
Barbashev had a power-play goal off a rebound at the right post for the 3-0 final at 18:36.