Pitts burg had lost six of seven heading into Saturday's game at Air Canada Centre and had not had Gonchar in the lineup for the past four.
"It's good to see that we've found the top of our game," Gonchar said. "We know what we're capable of."
Matt Stajan scored the only Toronto goal. Jonas Gustavsson made 35 saves.
Gonchar broke a 1-1 tie late in the second period on a power-play goal that had been initially waved off by the officials but was confirmed by a video review. His second goal at 17:17 of the second gave Penguins a 3-1 advantage.