Kevin Shattenkirk registered a power-play goal 2 win over the Edmonton Oilers.
Andy McDonald scored two goals for the Blues, who have won each of their first four stops on a six-game trek.
Jaroslav Halak made 22 saves to match St. Louis batterymate Brian Elliott with 20 wins. It marks the first time in Blues history that two goalies have posted at least 20 wins in a season.
Rookie Ryan Nugent-Hopkins and Corey Potter lit the lamp for Edmonton, which entered Wednesday's game having won three of four. Devan Dubnyk surrendered three goals on 19 St. Louis shots before being replaced by Yann Danis, who recorded 10 saves in his first NHL appearance this season.