Rask, who backstopped the Bruins into the Stanley Cup finals during the recently completed season, will get $7 million per year, the team said.
The 26-year-old Finn came into his own this past season after taking over as the starting goalie for the departed Tim Thomas. He posted a 2.00 goals-against average and .929 save percentage while compiling a 19-10-5 mark with five shutouts in the regular season.
Rask also turned in a stellar post-season, going 14-8 with an NHL-best .940 save percentage, a 1.88 GAA and three shutouts.
He has gone 66-45-16 with a 2.15 GAA and 16 shutouts over 138 regular-season appearances in six seasons with Boston, including a 21-14 record and 2.14 GAA in 35 playoff contests.