New York's Denis Potvin, driving to break Bobby Orr's all-time career scoring records for defensemen, scored the game-winning goal in Winnipeg.
With his fifth goal of the season, Potvin gave the Islanders a 2-0 lead midway through the first period and drew within four points and five goals of Orr's 270 goals and 915 points.
New York built a 3-0 first-period lead on goals by Bryan Trottier, Potvin and rookie Neal Coulter in handing the Jets' their fifth straight loss.
Trottier opened the scoring with a 25-foot wrist shot at 6:16, set up by Patrick Flatley's pass from the corner, and five minutes later, Potvin connected with a wrist shot from almost the identical spot.
After Coulter's 10-foot backhand flip to goalie Brian Hayward's side at 13:18, Hayward was replaced by Dan Bouchard. The goaltending change gave life -- if not goals -- to the Jets, who had been outshot at that point, 8-2. But by the end of 20 minutes, the teams were tied in shots, 8-8, as the Islanders received steady goaltending from Billy Smith to protect their three-goal lead.
Dale Hawerchuk cut the Islanders' lead to 3-1 with his 14th goal of the season, on a rebound from newly acquired Mario Marois at 18:27 of the second period. John Tonelli scored the only goal of the third period at 16:57.