Mike Johnson and Paul Kariya each had a goal and assist, Martin Rucinsky also scored, and Boyes added an assist for St. Louis. The Blues have won three straight and seven of their last eight games.
Jason Pominville, Ales Kotalik and Andrej Sekera scored for Buffalo. The loss snapped the Sabres' winning streak at five.
The Sabres are winless in their last 11 games against St. Louis -- including eight loses in regulation -- and haven't beaten the Blues at home in more than 12 years.
Boyes' notched his fourth winner of the season, banging home his own rebound after Sabres forward Daniel Paille stopped the original shot that was headed into the net.
Buffalo goalie Ryan Miller finished with 28 saves.
The Sabres scored first for the sixth straight game when Pominville redirected Clark MacArthur's pass from the high slot with just 1:21 remaining in the first period for his seventh of the season. It was Pominville's second goal in two games after he was held goal-less for 13 straight games.