Jean-Sebastien Giguere made 29 stops en route to the win.
David Backes notched a goal and an assist for the Blues, who missed a chance to clinch a Western Conference playoff spot with a victory.
Jaden Schwartz and Kevin Shattenkirk each found the net in the loss.
Brian Elliott started in net but was pulled in the second period after yielding four goals on 19 shots.
Jake Allen relieved, turning aside 11-of-12 Colorado tries the rest of the way.