Gunnarsson would have become an unrestricted free agent on Monday.
Gunnarsson, 32, has 28 goals in 581 career games, but one stands out above the rest. Gunnarsson scored in overtime of Game 2 to knot the Stanley Cup Final, which St. Louis went on to win over the favored Boston Bruins.
Gunnarsson had clanged a shot off the pipe late in the third period of Game 2. He confirmed that, during the intermission before the OT, he told Blues coach Craig Berube that he just wanted another chance. The conversation took place at the urinals.
Before the big goal, it was a trying season for the Swede. He played in only 25 regular-season games as he recovered from ACL surgery. He then missed time in the playoffs with another lower-body injury.
Gunnarsson is coming off a three-year, $8.7 million contract. He also played five years for Toronto.