After missing the last two games with a back injury, Fedorov returned in style by scoring on his first two shots. He completed his second hat trick of the season and sixth of his career with his 27th goal at 4:42 of the second period to chase Blues goaltender Fred Brathwaite.
Fedorov later picked up an assist to complete a four-point night. He has seven goals and 13 assists during an 11-game points streak.
Former Blue Curtis Joseph made 29 saves to raise his record to 8-1-0 in his last nine games.
Shjon Podein and Pavol Demitra scored for St. Louis, which had its four-game winning streak snapped.
The Blues failed to gain a boost with the return of Keith Tkachuk and Doug Weight to the lineup. Tkachuk served a four-game suspension for cross-checking Minnesota's Wes Walz on Feb. 23 while Weight missed 10 games with a broken bone in his face.