The team made the announcement on its official website, and while no financial terms were revealed, reports have suggested it could be worth $17 million US. The 24-year-old would have become a restricted free agent on July 5.
Shattenkirk has been an important cog in the Blues' defence corps, forming a formidable tandem with Alex Pietrangelo and registering 43 points, including nine goals, in his first full season in a St. Louis uniform in 2011-12. He had 23 points in all 48 games last season.
Shattenkirk, a native of Greenwich, Conn., has 23 goals and 86 assists in 201 career regular season games with the Blues and Colorado Avalanche.
The five-foot-11, 207-pound rearguard was originally drafted in the first round (14th overall) in 2007 by the Avalanche and was shipped to St. Louis in 2011, along with Chris Stewart and a second-round pick, in exchange for Erik Johnson, Jay McClement and a first-rounder.
It was the second signing of the day for the Blues, as they announced earlier a new one-year deal for forward Patrik Berglund.The Vesteras, Sweden native ranked fourth on the team last season with 25 in 48 games. The 25-year-old has 188 points (92 goals, 96 assists) in 358 career regular season contests.