Financial terms were not announced, but local media reported the deal worth $29 million.
The agreement enables Chicago to keep under contract through 2014 many of the key players from their 2010 championship run.
"Brent is a very important member of our organization and we are looking forward to him being part of a core group that will be a contender for many years to come," Blackhawks general manager Stan Bowman said in a statement.
The 25-year-old Seabrook, a member of the Blackhawks for his entire six-season NHL career, has four goals and a career-high 29 assists this season.
(Reporting by Gene Cherry in Salvo, North Carolina. Editing by Steve Ginsburg)