Dubielewicz, a 28-year-old career minor-leaguer, is expected to serve as Rick DiPietro's backup next season. He agreed to a one-way NHL contract that will pay him $500,000.
"Wade really earned this opportunity," Islanders general manager Garth Snow said. "He has developed steadily with each season in [AHL] Bridgeport and played well whenever the Islanders needed him."
He played especially well late in the season, after DiPietro's second concussion in a span of 12 days. Mike Dunham was ineffective in his place, prompting Ted Nolan to make the change.
With Dubielewicz between the pipes, New York won its final four games -- two by shootout -- and beat New Jersey on the final day of the season to secure the last playoff spot in the Eastern Conference.
"Wade's play down the stretch was instrumental in our team making the playoffs," Snow said.
Dubielewicz had played only nine NHL games before this season. In four full seasons with Bridgeport, he was 58-52-8 with 13 shutouts.
The one-way contract virtually ensures he will spend all of next season in the NHL.
"Although it's a big plus knowing I'll be an Islander next year, my plan is to come to camp in the best shape of my life and be ready for a great season for our team," Dubielewicz said.