DiPietro needed to stop just nine shots, while the Islanders pelted Kari Lehtonen for 49. DiPietro also added an assist as 12 Islanders recorded a point.
"As far as team defense, this has been our best game in a while," DiPietro said. "What we did tonight was a real big step."
Miroslav Satan, Ruslan Fedotenko, Marc-Andre Bergeron and Sean Bergenheim scored for the Islanders, winners of three straight.
The three consecutive wins came after a seven-game losing streak (0-6-1). During those seven games, New York scored just 11 goals. They've scored 13 in the three wins.
New York's previous low for shots allowed in a game was 11, set on Mar. 3, 1977 at Detroit.
"There was a method to our madness tonight," Islanders coach Ted Nolan said. "It's one thing to throw pucks at the net, and it's another to throw them at the net when someone's in front. Tonight, we scored three goals that way. It was a good, solid team effort."
Atlanta had a three-game winning streak snapped with the loss. Lehtonen stopped 45 shots, and Todd White scored for the Thrashers.
"It's very frustrating to go from the high of last night to this," Atlanta coach Don Waddell said of his team's come-from-behind 4-3, 10-round shootout victory over New Jersey on Friday. "Complacency is a fair statement. We have some success, and we seem to have a hard time dealing with it."
The Islanders tied a season high with 20 shots in the opening period, and set a season record with 49 shots. Still, they emerged from the opening 20 minutes with just a 1-0 lead.
Satan's 12th goal of the season, and first in 10 games, came at 14:52.
The Islanders outshot Atlanta 17-2 in the second period, and increased their lead to three.
Fedotenko continued his torrid scoring pace when he made it 2-0 for New York 90 seconds into the period. He skated around the net and tried a backhand wraparound. Lehtonen made the initial stop, but Fedotenko swept the rebound home.
"I feel our line's playing better," Fedotenko said of Trent Hunter and Josef Vasicek. "Everything's working right now."
Fedotenko now has goals in three straight games, and five goals in his last five. He, Hunter and Vasicek have combined for 11 points in the last three games.
Bergeron scored on the front end of a two-man advantage at 12:03 to give the Islanders a three-goal margin. His center point slap shot flew over Lehtonen's right shoulder.
"I don't want to remember anything about this game," Lehtonen said. "On night's like this, and we've had a few of these this season, we don't look like a playoff team."
Islanders forward Trent Hunter (7) had more shots after 40 minutes of play than the entire Thrashers team (6).
"They were the more desparate team right from the start," Waddell said. "When you play all night in your own zone, it's hard to create offensive chances."
