A source tells ESPN.com's Pierre LeBrun the deal has a $3.9 million average salary, making it worth $23.4 million total.
The Canadiens announced the deal with their assistant captain on Sunday.
The 27-year-old Gorges is in his sixth year with Montreal. He leads the team with a plus-6 rating and 101 blocked shots over 39 games. He also has one goal and nine assists.
Information from ESPN.com's Pierre LeBrun and The Associated Press was used in this report.