After capturing Game One in a 3-0 triumph, the Bruins blitzed the Penguins with four goals in the first period as they skated to a commanding 2-0 lead in the best-of-seven series.
"We're obviously very happy with the outcome," Boston winger Brad Marchand told reporters after scoring two goals in the victory.
"I was just trying to make sure I skated as hard as I could. It's so fast out there, they can create chances. You always have to be on your toes."
Boston, who host Game Three on Wednesday, again dominated Pittsburgh goaltender Tomas Vokoun, who allowed three goals on 12 shots before being pulled from the game in favour of previous starter Marc-Andre Fleury.
Vokoun emerged as the main man in net during his team's first round series, but he has been helpless against the Bruins offense.
Marchand, Nathan Horton and David Krejci gave the visitors a 3-0 advantage in the first.
Brandon Sutter notched Pittsburgh's only goal in the final minute of the opening period, but Marchand responded with a second score seconds later.
Patrice Bergeron and Johnny Boychuk added goals for the Bruins in the third.
Boston's Tuukka Rask made 26 saves and watched his offense make the most of every opportunity. (Writing by Jahmal Corner in Los Angeles, editing by Nick Mulvenney)