Patrik Berglund also scored and Brian Elliott stopped 22 shots for the Blues, who finished the regular season with three straight wins and clinched the fourth seed in the Western Conference with a 29-17-2 record.
Ben Smith tallied for the Blackhawks, who earlier wrapped up the President's Trophy for the best record in the NHL.
They concluded the regular season with a 36-7-5 mark and will face eighth-seeded Minnesota in the first round.
Carter Hutton turned aside 25 shots for Chicago in his NHL debut in goal.
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