Anaheim was able to kill off its first penalty of of the game, but 13 seconds later, Killorn was assessed a minor for hooking at 12:17. He then received an unsportsmanlike penalty for slamming the door to the penalty box.
Eleven seconds into the second penalty, Nelson scored on a one-timer from the slot to push it to 3-0 at 14:28.
Killorn scored 24 seconds into the second period to cut the lead to 3-1.
Horvat scored 34 seconds into the third period to make it 4-1. He got the puck at the edge of the crease after Nelson partially fanned on a shot and scored into an open net past Dostal's outstretched glove.
Pierre Engvall extended the lead to 5-1 on a partial breakaway at 7:56, and Cal Clutterbuck scored from the slot with 1:48 remaining for the 6-1 final.
"The ones that sting are the ones like tonight where there isn't a whole lot going on, some good things defensively, and then two or three times we just have a brain lapse and it ends up costing us," Ducks defenseman Cam Fowler said. "So, it's just continuing to grow as a group, helping the young players out as much as we can, and trying to come up with a more consistent 60 minutes of hockey."
NOTES: The Islanders' winning streak is their longest since a nine-game run from Feb. 28 to March 14, 2021. ... Varlamov had lost his previous seven starts (0-4-2). His previous win also came against the Ducks. ... Barzal extended his point streak to seven games (three goals, six assists). ... Nelson has 10 points (four goals, six assists) during a five-game point streak. ... Horvat went 13-for-17 on face-offs (76.4 percent).