Fleury turned aside all 24 Sabres shots for the Pens, who rebounded from a shutout loss at Dallas Saturday.
Deryk Engelland, Tanner Glass and Chris Kunitz each scored as Pittsburgh recorded a fifth win in seven games overall.
Ryan Miller stopped 31-of-34 shots for Buffalo, losers of six in seven.
Notable deaths of 2014 [PHOTOS]
UPI horse racing roundup