Edmonton allowed nine power-play goals in its previous six games and gave up two more as the Penguins took a 3-1 lead early in the second period.
The Oilers overcame the deficit as Ryan Smyth scored 64 seconds after Brian Holzinger's power-play tally. The turning point came in the opening minute of the third, when Adam Oates won a faceoff from Mike Eastwood and passed to Cory Cross, who fired a long slap shot past rookie goaltender Marc-Andre Fleury.
Oates won 14-of-20 faceoffs, none bigger than his first draw of the final period.
The Oilers got an insurance goal 2 1/2 minutes later as Georges Laraque used his 243-pound frame to muscle his way to the crease and Horcoff tapped in his rebound to end a nine-game drought.