Shattenkirk played in all 48 games in 2012-13, ranking second among Blues defensemen with 23 points. During the Stanley Cup Playoffs, he tied for the lead among Blues defensemen with two points in six games.
He would have been a restricted free agent had he not signed by July 5.
In 2011-12, his first full season with the Blues, Shattenkirk (43 points) and Alex Pietrangelo (51 points) became just the fourth set of defensemen in team history to each record over 40 points in the same season. One season earlier, Shattenkirk became just the second rookie defensemen in NHL history to record a point streak of at least nine games.
He was selected by Colorado Avalanche in the first round (No. 14) of the 2007 NHL Draft, and was acquired by the Blues, along with Chris Stewart, from Colorado on Feb. 19, 2011. Since breaking into the League in 2010, Shattenkirk ranks fourth among American-born defensemen with 109 points and is fifth with 23 goals and 86 assists in 201 games spanning three seasons.
Shattenkirk is the second player signed by the Blues on Wednesday. Earlier, the team announced center Patrik Berglund had signed a one-year contract extension prior to becoming a restricted free agent.