Michael McLeod one-timed a cross-ice pass from Damon Severson just inside the right post to give New Jersey a 2-1 lead at 15:31 of the second period.
"We're playing some good hockey as of late, beating some pretty big teams that could go pretty far in the playoffs," McLeod said. "That's huge for us heading into the offseason, just getting that confidence as a team that we can beat these teams. If we play the right way, we're going to get the results we want."
The Islanders outshot the Devils 13-5 in the third period but failed to generate enough high-quality opportunities against Blackwood, who has won his past five starts.
"We've passed up a lot of chances," Trotz said. "A 2-on-1 where we don't even get a shot, or we don't execute on a play and you get nothing out of it. We've got to be better, we've got to execute better. We've got to wrap our minds around getting prepared for the playoffs, not just waiting for it, because it's not a switch."
It was the first game against the Devils for forwards Kyle Palmieri and Travis Zajac since being traded to the Islanders on April 7. Palmieri has scored one goal in 15 games for New York, and Zajac has scored one goal in 12 games.
"I came in here and obviously want to try and find a way to fit in and contribute," Palmieri said. "I think there's been games where I've felt good and brought some positive things out of it, but it's hard to find that right now. It hasn't exactly gone the way I hoped, but right now I'm focused on trying to get better every day and being a good teammate along the way and showing up and just working.
"I think as a group we're excited to try and find our game here the next two games, and we're really looking forward to getting into playoff hockey."
NOTES:Devils forward Jesper Boqvist left with 1:11 remaining after being struck in the face by a stick. "Maybe just a bloody nose. I'm hoping that's all," Ruff said. … New Jersey forward Miles Wood did not play because of an upper-body injury. He is day to day. Wood was replaced by forward Tyce Thompson, who had one shot in 10:24. … Beauvillier extended his point streak to five games (five goals, one assist). … Islanders center Mathew Barzal had one shot and was minus-1 in 21:37 of ice time after being a healthy scratch at the Buffalo Sabres on Tuesday. … Forwards Jordan Eberle and Leo Komarov, and defenseman Andy Greene were healthy scratches for New York. Trotz said he is trying to keep players fresh for the playoffs.