Marat Khusnutdinov, Viktor Arvidsson and David Pastrnak also scored, and Charlie McAvoy had two assists for the Bruins (27-19-2), who have won seven of their past eight. Jeremy Swayman made 26 saves.
Boston defenseman Andrew Peeke left the game with a lower-body injury late in the first period and did not return.
Chandler Stephenson and Eeli Tolvanen scored for the Kraken (21-16-9), who have lost four of five (1-3-1) and lost in regulation for the second time in 14 games (9-2-3). Joey Daccord made 20 saves.
Seattle was coming off a 3-2 overtime loss at the New Jersey Devils on Wednesday.
Khusnutdinov gave the Bruins a 1-0 lead 54 seconds into the first period. McAvoy banked a stretch pass off the boards near the Kraken bench, allowing Khusnutdinov to retrieve it with speed and beat Daccord with a forehand-to-backhand deke. Seattle allowed the first goal 54 seconds into the game for the second straight night.
Arvidsson increased the lead to 2-0 at 3:45. Pavel Zacha entered the offensive zone and made a cross-ice pass to Arvidsson, who attempted a centering pass to Casey Mittelstadt from the left side before the puck ricocheted off the stick of Kraken forward Jaden Schwartz and into the net.
Seattle cut the deficit to 2-1 on Stephenson’s power-play goal at 7:29. He was positioned in front to redirect Jared McCann’s centering pass.
Kastelic then pushed the advantage to 3-1 at 4:40 of the second period. He stripped the puck from Matty Beniers inside the Seattle blue line, gained control and skated in on Daccord before chipping a backhand to the short side.
Tolvanen cut it to 3-2 at 12:27 with a power-play goal, one-timing a loose puck in the right circle.
Pastrnak scored an empty-net, power-play goal with 15 seconds remaining in the third period for the 4-2 final.
The Bruins retired Zdeno Chara’s No. 33 before the game, honoring his Hockey Hall of Fame career that included winning the Stanley Cup in 2011 with Boston. A Norris Trophy-winning defenseman with the Bruins in 2008-09, Chara was captain for all 14 of his seasons in Boston (2006-20).
