St. Louis had a 23-9 shots advantage after two periods but trailed 3-1.
"Obviously, we didn't generate as many shots as we wanted to in the first couple of periods," said Bell, who scored his team-leading 13th goal. "But Khabby won the game for us. He was great in the first two periods and he made some key saves in the third period, and we got some timely goals."
Among Khabibulin's saves was a blocker deflection of Doug Weight's penalty shot at 8:22 of the second period. Weight was awarded the attempt after Chicago's Kyle Calder covered the puck and then threw it from a pile-up in the Blackhawks crease.
"I was trying to remember what he [Weight] likes to do, but then I couldn't remember anything," Khabibulin said. "So I just tried to be patient and tried to make him make the first move."
Khabibulin stopped Weight with Chicago leading 2-0. The Blues forward said he did everything according to plan, except score.
"I was wondering what I hit, because I know I got it over the pad," Weight said. "I shot it where I wanted it, went in at the right speed and he made a good save."
Dean McAmmond scored for the Blues, who have won just one of their last five games and two of nine.
St. Louis coach Mike Kitchen said Tkachuk would probably be out four to six weeks. He missed 15 games earlier this season with non-displaced cracked ribs and now becomes a question mark to be picked Monday for the U.S. Olympic hockey team.
Tkachuk's five-game goal streak and seven-game point run were snapped. He had eight goals and seven assists in seven games before Friday.
Sanford got back on his skates but was helped to the bench. He was later diagnosed with a hip flexor pull. Kitchen said he wasn't sure how long Sanford would be sidelined.
Sanford allowed two goals on four shots before being replaced by Jason Bacashihua, who gave up two goals on 16 shots in making his NHL debut.
"It's not the way I thought my first NHL game would be," Bacashihua said. "But I skated well this morning and felt confident going in."
The Blues had recalled the 23-year-old goalie from AHL Peoria on Monday.
Hilbert opened the scoring on a deflection at 8:33 of the first period. As Hilbert cut across the slot, Rene Bourque's shot from just inside the blue line struck him and bounded past Sanford.
Lapointe made it 2-0 with 1:12 left in the first. He scored from the crease, after being set up by Kyle Calder following a St. Louis turnover.
McAmmond cut it to 2-1 just over two minutes after Khabibulin stopped Weight on the penalty shot.
Bell's power-play goal with 3:52 left in the second gave Chicago a 3-1 lead. He beat Bacashihua with a high shot from the top of the right circle.
Vorobiev's empty-net goal with 1:37 left made it 4-1. Dowd completed the scoring, with Bacashihua back in goal, with two seconds left.
Blackhawks defenseman Michal Barinka missed the game with concussion-like symptoms, caused by a hit by Nashville's Scott Hartnell on Thursday. ... Chicago defenseman Todd Simpson returned after missing two games with a knee injury. ... Chicago defenseman Adrian Aucoin
missed his third straight game with a groin injury. ... St. Louis right winger Dallas Drake missed his fourth game with a sore lower back.