It was the second straight two-point game for Horak, who scored his first NHL goal Wednesday night in a 4-2 victory over Colorado.
"With every point and when you're getting more ice time, that gives you more confidence," said Horak, who played the past three seasons with the Chilliwack Bruins of the Western Hockey League.
Horak was a plus-2 and logged 17:39 in ice time Friday.
"Hockey is all about having that confidence so it feels great when you're out there and the coach trusts you to put you out there," Horak said.
Horak is five years younger than the second-youngest player on the active roster, 25-year-old defenseman Chris Butler.
"He brings a lot of energy. He's enjoying every minute of it, and he's a smart hockey player, too," said winger Tim Jackman, who had two assists. "Earlier, we were thinking where is he? Now it seems like he's always in the right spot. He's a fast learner and you can see how talented he is by the way he's playing."
Alex Steen scored his team-leading sixth goal of the season for St. Louis (5-5-0), which had its three-game winning streak snapped.
Calgary gained momentum halfway through the third period when St. Louis had a power play for over 3 minutes, including a 54-second two-man advantage, but couldn't score.
The Blues entered the game with the NHL's worst power play, having scored a league-low two goals. Despite firing five shots on Kiprusoff during that critical stretch -- the most dangerous chances coming from Carlo Colaiacovo and Matt D'Agostini -- the Blues couldn't capitalize.
"We moved the puck decent, but not terrific," Steen said. "We had two or three good looks and we had a couple of chances that we should have buried."
St. Louis is 1-for-28 with the extra man in its last eight games.
"When it's going like it is, the power play just has to continue to work and has to continue to find ways to be a little sharper and more determined," Blues coach Davis Payne said.
After surviving the scare, Horak got free in the slot and snapped a shot that squeaked through Brian Elliott's pads at 12:16.
"A lucky shot, but it went in," Horak said. "The goal was huge but great work from Jackman behind the net and a great pass from Glennie."
The two-goal lead lasted only 12 seconds, with Steen scoring on a long shot through a screen.
For the second straight game, the Flames dressed 11 forwards and seven defensemen. ... Calgary C Brendan Morrison played in his 900th game. He's one of three Flames to have reached that mark, joining Jarome Iginla (1,115) and Jokinen (969). ... Calgary is 10-2-1 in its last 13 home games against St. Louis.