CHICAGO (AP) -- Michael Leighton's second NHL shutout turned out better than his first.
He played in a scoreless tie in his NHL debut last season for offense-starved Chicago.
"The team played great tonight," Leighton said. "Having a three-goal lead felt great. That's a game you have to win.
"And the team played well defensively. I just can't say enough about it."
Steve Sullivan, Scott Nichol and Tyler Arnason scored for the Blackhawks, who won for only the second time in 21 games (2-12-4-3). They also ended a five-game winless streak (0-3-2).
Chicago scored three goals or more for the first time in six games, the second time in 11 and third time in 17 contests. The Blackhawks entered Tuesday's game with 63 goals, second fewest in the NHL.
"It was huge," Sullivan said of the three-goal output. "We've been known to blow a one-goal lead in the third period. We kept scoring and working after we got the first goal."
The Blues have lost two straight following a nine-game unbeaten streak when they went 7-0-2.
"I don't think we crashed the net enough," St. Louis coach Joel Quenneville said. "I know that we were looking to score ugly goals and trying to get some plays where you get the fortunate bounces. That did materialize because I don't think we pursued that territory enough."
St. Louis goalie Brent Johnson, playing in only his eighth game, made 18 saves.
'I wasn't as sharp as I could have been, but I hadn't played in a while," Johnson said. "I was just trying to do a bit too much and overreacting, especially on Arnason's goal."
Sullivan opened the scoring 1:41 in after beating Blues defenseman Chris Pronger in the slot.
Sullivan broke in over the St. Louis blue line and faked his way around Pronger, who was caught flat-footed. After fanning on his first shot attempt, Sullivan then slid a shot between Johnson's legs.
Nichol made it 2-0 at 1:27 of the third with a wraparound goal from behind the net.
After picking up the puck in the right corner, Nichol skated behind the net and tucked a shot between Johnson's legs from the left edge of the crease.
Arnason gave Chicago a 3-0 lead 2:02 later with a breakaway goal. He picked up a loose puck at center ice, skated in alone and beat Johnson with a high shot on the stick side.
Leighton's toughest stop in the third period was a glove save on Christian Backman's 40-foot shot at 7:30.