Sebastien Caron stopped 24 shots in his debut in goal for Chicago. The Blackhawks signed him as a free agent on Aug. 8. Chicago's Bryan Smolinksi scored a power-play goal into an empty net with 13 seconds left in the third period.
Injury-decimated Chicago hadn't won since defeating Montreal at home on Oct. 18, going 0-7-1 during the slide. Three of the Blackhawks' top players - forwards Martin Havlat and Michal Handzus, and top goalie Nikolai Khabibulin - are out.
Lee Stempniak scored for the Blues, who dropped their third straight and are 1-5-1 in their last seven.
Vrbata's first goal snapped Chicago's six-game, 0-for-25 power-play slump.
The Blues' Curtis Sanford made 15 saves.
Vrbata's goals in the first gave Chicago a 2-0 lead after 20 minutes.
He opened the scoring at 9:33. Vrbata knocked in a loose puck from the left edge of the crease after Jeff Hamilton's high, weak shot from the right point struck Blackhawks' forward Tuomo Ruutu in the chest and the puck dropped to the ice.
Vrbata made it 2-0 with 2:07 left in the period. From the front of the crease he deflected in Hamilton's shot from the right point.
Stempniak cut it to 2-1 with 2:13 left in the second. Left wide open in front of the net, he beat Caron from 10 feet out after taking Keith Tkachuk's centring pass from behind the net.
In three game against Chicago this season, Stempniak has three goals and three assists.
Caron made a couple of close-in saves in the scoreless third, but wasn't heavily tested.
Sanford stopped Chicago's Rene Bourque on a breakaway with 6:50 left.
St. Louis's Bill Guerin fanned on a close-in chance during a St. Louis power play with just over three minutes remaining.
Notes: Caron played 26 games with Pittsburgh last season. ... The Blackhawks recalled D James Wisniewski from Norfolk of the AHL on Friday, but he didn't dress. ... Chicago LW Tony Salmelainen missed his fourth game with a separated shoulder. ... Blackhawks C Denis Arkhipov was struck in the left leg with a shot in the third and had to be helped from the ice. ... St. Louis RW Dallas Drake missed his second game with a sore foot. ... Blues D Dennis Wideman sat out his third game with a sore hand.