The Penguins had lost four of five and were 5-6-2 since Fleury last played on Nov. 15 in a victory over the Buffalo Sabres. He showed little rust against Atlanta, which held a 31-19 shots advantage.
"He was phenomenal," Penguins coach Michel Therrien said. "He made key save after key save. I'm more than pleased with his performance."
Once Fleury settled down and was given a cushion by the offense, he felt much better, too. He even put the injury out of his mind.
"I was a little nervous, but after a couple of shots, I was OK," Fleury said. "I was relieved when we got the first two goals. After that, I didn't think about it much."
Malkin, who has 53 points, helped take the pressure off. He netted his 13th goal in the first period, added his 38th and 39th assist in the second period and scored into an empty net with 26.2 seconds left. He has 14 points during a seven-game scoring streak.
"Malkin played an outstanding game," Therrien said.
The big story, though, was Fleury's successful return.
"He was sharp, especially after being off a month," Pittsburgh captain Sidney Crosby said.
Crosby has gone eight games without a goal but had two assists to raise his point total to 46 -- second in the NHL to Malkin. He passed up an open-net chance and gave the puck to Malkin in the closing seconds.
"As nice as goals are and as nice as empty nets are, you just have to trust your instincts," Crosby said. "I saw him open and made a play."
Staal and Satan scored on Pittsburgh's first two power plays early in the second period and Atlanta rookie goalie Ondrej Pavelec was pulled after Boucher scored at even strength to make it a three-goal game at 8:04 of the period. The rookie stopped just 8-of-13 shots before being replaced by Johan Hedberg.
Staal's power-play goal came at 3:30, then Satan scored his 12th goal at 5:54. Little cut Pittsburgh's lead back to two goals with his 12th on a power play at 7:32. But Boucher scored just 32 seconds later for the Penguins.
Armstrong, traded last season to Atlanta by the Penguins in the Marian Hossa deal, scored an unassisted goal with 5:05 left.
"We can't let any mistakes creep into our game or else we pay for it," Atlanta coach John Anderson said. "We get so far behind that we can't catch up."
Pittsburgh scored on two of its first four shots, with Cooke and Malkin getting goals at 5:32 and 9:40 of the opening period.
Atlanta cut Pittsburgh's lead to 2-1 with 39 seconds left in the first period. Ilya Kovalchuk's slap shot deflected off Reasoner and past Fleury into the net. A melee followed the goal, with Crosby giving Atlanta a power play by drawing the third roughing penalty.
"I threw one [punch], but I didn't land it," Crosby said.
Defenseman Scott Lehman, called up by Atlanta from AHL Chicago, made his NHL debut. He replaced defenseman Garnet Exelby, who is out with a lower body injury. ... Pittsburgh played forwards Jeff Taffe and Ryan Stone in place of Maxime Talbot and Mike Zigomanis, who are sidelined by injuries. Taffe and Stone were promoted from AHL Wilkes-Barre/Scranton. ... Pittsburgh started a stretch of four games in six days.