Halak made 33 saves for his 28th career shutout and third this season to lead the Blues to their seventh consecutive victory with a 5-0 win Thursday night.
Calgary took a 4-1 edge in shots three minutes into the game, but Lee Stempniak and Dennis Wideman then took back-to-back minor penalties. St. Louis took a 1-0 lead when Chris Stewart scored 18 seconds after Wideman's penalty expired.
Vladimir Sobotka scored just over two minutes later and that would turn out to be more than enough offense for Halak, who improved to 18-6-3.
"Especially in the first period, they had a few chances that got me into the game," Halak said. "Then we started playing better and we didn't give them pretty much any chances the rest of the first."
Calgary has lost six of seven since, and it's also the fifth time in seven games the Flames have been shut out.
The teams last met on Dec. 23. In that game, also played at the Scotiabank Saddledome, the Flames came from behind for a 4-3 victory.
Calgary's offense has struggled since, scoring just five times in seven games -- four coming Monday in a 4-3 victory in Colorado. In the Flames' past five games at home they've mustered only one goal, on Dec. 31 by rookie Sean Monahan.
"We got outplayed in pretty much every facet of the game tonight," said Stempniak, who has no goals in his past 15 games. "I'm a big believer in earning your breaks and earning your luck out there. We haven't been playing well enough to get those chances."
Flames coach Bob Hartley said the slump is taking its toll.
"To score goals, that's the toughest thing to do in the NHL," Hartley said. "I feel for my players because I see them work every day. For many players, it's pretty tough to ask more than what they're giving us right now. They care, I see them basically mentally destroyed after some games, but we're proud and we're going to keep fighting."
Stempniak said he has never been a part of this type of scoring drought.
"Individually, guys go through some tough times but never something that affected the whole team," Stempniak said. "You just have to think you're going to get out of it and believe you're going to get out of it."
The Blues pulled even in points with Chicago atop the Central Division, while Calgary has lost five home games in a row in regulation for the first time since March 7-31, 2000.
Halak hadn't played in five games while battling illness since getting pulled after the first period on Dec. 28 after getting beaten three times on 13 shots.
"When you go through the sickness, you're low on energy and you get tired all the time but now, I'm trying to work my way back," Halak said. "I'm not 100 percent back with my energy yet, but I battled through it and it was a big win for us.
Recently named to the Slovakian Olympic hockey team, Halak made an opening-minute stop on Paul Byron's breakaway and never looked back. In one of the Flames' best chances, Jiri Hudler rang a shot off the goal post in the second period.
"Jaro had to be there in the second period for us," Blues coach Ken Hitchcock said. "They make it 3-1 or 3-2, she's a different game in the third. He shut the door and good on him."
Karri Ramo finished with 24 stops, but fell to 7-8-3.
"We said right from the start that we were starting a rebuild," Hartley said. "We're hitting major speed bumps right now and overall if we look at the positive side, they're tough lessons, but that's going to make us better."
With points in their last 10 (9-0-1), the Blues are one back of their team record of 11 (10-0-1), which was set Jan. 21, 1999, to March 4, 2000. ... David Jones (eye) did not play for the Flames. He's missed three games. Calgary's only healthy scratch was D Derek Smith. ... In the past 11 games, the Flames have only led for 15 minutes, 25 seconds -- all of that coming in their only regulation victory. ... Calgary's power play is 1 for 20 in the past seven games. That stretch has come without Kris Russell (knee), who missed his eighth game.