Patrice Bergeron, Jake DeBrusk, Taylor Hall and David Krejci also scored, and Charlie McAvoy had four assists to help Boston equal the season-opening home mark set by the Blackhawks in 1963-64 and matched by the Florida Panthers last season.
It was the sixth straight victory for the Bruins (16-2-0). Boston hits the road for two games this week — against Tampa Bay and Florida — before returning home to host Carolina for its annual Black Friday matinee.
Behind a fired-up TD Garden crowd that broke into numerous chants of “Let’s Go Bruins,” Boston jumped to a 2-0 edge early in the second period en route to matching its season-high for goals in a game.
Playing his first game since leaving with a left knee injury from a collision with Bergeron, Bruins goalie Jeremy Swayman made 17 saves.
Taylor Raddysh scored a power-play goal for Chicago and Petr Mrazek stopped 37 shots. The Blackhawks have lost three straight.
With Boston on the power play, Pastrnak took a cross-ice from Brad Marchand just inside the right circle and slipped a wrister that slipped under the pads of Mrazek 4:53 into the game.
The Bruins led 1-0 after one period and it could have been a lot more because they outshot Chicago 15-3 and had a handful of excellent close chances.
Bergeron one-timed McAvoy’s pass inside the left post, making it 2-0 at 4:28 of the second.
Raddysh, positioned in the slot, tipped Max Domi’s shot into the net for a power-play score that sliced it to 2-1
But DeBrusk and Krejci scored a little over a minute apart late in the second, making it 4-1. Pastrnak’s second came midway into the third.
HOW THE WEST WAS WON
The Bruins improved to 8-0 against Western Conference teams.
Bergeron needs one point for 1,000 in his career. He’d become the fourth Bruins player all-time to reach that mark. ... Chicago forward Patrick Kane turned 34 on Saturday. … The Blackhawks had killed off all their penalties in the previous four games before Boston scored on its first power play. … Both teams wore reverse retro jerseys. … Mrazek played his 301st career game.
Blackhawks: Host the Pittsburgh Penguins on Sunday.
Bruins: At the Tampa Bay Lightning Monday.
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Ken Powtak, The Associated Press