The deal, which includes a club option for a third season in 2008, is worth a guaranteed $25.75 million US.
"This is a great opportunity for both the Cardinals and Jason, who shared our interest in getting an extension done," general manager Walt Jocketty said.
"This deal gives us financial certainty while securing one of the game's elite closers for the next few years."
Isringhausen, 32, posted a career-best 47 saves last season, tying then-Florida Marlins reliever Armando Benitez for tops in the National League.
The St. Louis stopper finished with a 4-2 record and 2.87 earned-run average over a career-high 74 appearances. He blew seven saves on the season.
Isringhausen has also played with the New York Mets and Oakland A's in his pro career. He holds a 35-34 career mark with a 3.72 ERA and 177 saves.
with files from Sports Network
