Nashville set franchise records in wins (50) and points (108). But the Predators had to wait and see how Detroit (110 points) fared against Chicago to know whether they had any hope of winning the Central Division.
Nashville wraps up its regular season Saturday night at Colorado, while Detroit hosts Chicago.
The Predators had been struggling with a three-game home skid that was the longest this season and in danger of losing a fourth consecutive game for the first time this season. They finally fixed some problems against St. Louis, beating the Blues for the 15th time in 16 games.
Rookie Alexander Radulov and Peter Forsberg also had goals for Nashville, which scored twice on the power play in its final home game of the regular season.
Christian Backman scored the only goal for St. Louis, which had won three of four.