Jack Hughes had a goal and an assist, Jesper Bratt had two assists and Nico Daws made 16 saves for the Devils (6-4-0), who are 4-1-0 in their past five games.
Tim Washe scored, and Ville Husso made 25 saves for the Ducks (4-6-0), who lost their fifth straight. Anaheim concludes a four-game road trip at the Philadelphia Flyers on Saturday.
Gritsyuk opened the scoring on a tip-in to make it 1-0 at 4:38 of the first period. Jack Hughes passed to Bratt at the right circle, who found Gritsyuk in front to finish the tic-tac-toe play by tucking the puck past the right skate of Husso.
Gritsyuk, who signed a three-year, $9.75 million contract extension ($3.25 million annual average value) on July 3 with the Devils that begins next season, has five goals working on a line with Jack Hughes and Bratt.
Nico Hischier pushed it to 2-0 at 19:19 on the power play. Camped out in front of the crease, Hischier tapped in the rebound of Bratt's shot from the right dot.
Daws made eight saves in the second period. His best came at 9:43 when he denied an uncontested Beckett Sennecke on a wrist shot down the slot.
Washe pulled the Ducks within 2-1 at 8:20 of the third period, scoring on a deflection from the slot. Defenseman Jackson LaCombe earned the primary assist with a slap shot from the left point.
Anthony Mantha scored on the rebound to make it 3-1 at 13:27. Husso thought he had covered the puck after Brett Pesce's shot from outside the right circle, but Mantha was in front to poke it through.
Jack Hughes scored an empty-net goal at 19:53 for the 4-1 final.
