When Shattenkirk had a nine-game point streak for the Colorado Avalanche from Nov. 17-Dec. 4, 2010, it set him apart from almost every rookie defenseman in NHL history. Only Barry Beck had a longer scoring streak by a first-year defenseman; he had two 10-game streaks with the 1977-78 Colorado Rockies).

It was the beginning of a career that has seen him play a productive offensive role for five NHL teams and help the Tampa Bay Lightning win the Stanley Cup in 2020. Shattenkirk played 14 seasons in the NHL before retiring Dec. 10, 2024.

Selected by the Avalanche in the first round (No. 14) of the 2007 NHL Draft, Shattenkirk made his NHL debut with Colorado against the Vancouver Canucks on Nov. 4, 2010. Shattenkirk participated in the 2011 SuperSkills competition during NHL All-Star Weekend and finished the season with 43 points, the most among rookies. However, he didn't finish the 2010-11 season with the Avalanche.

On Feb. 19, 2011, Colorado traded Shattenkirk, Chris Stewart and a second-round pick in the 2011 NHL Draft to the St. Louis Blues for Erik Johnson, Jay McClement and a 2011 first-round draft pick. Shattenkirk made his debut with the Blues that day, getting an assist against the Anaheim Ducks.

In 2011-12, Shattenkirk's first full season in St. Louis, he and Alex Pietrangelo became the fourth set of defensemen in Blues history to each score at least 40 points in the same season. He made his Stanley Cup Playoff debut against the San Jose Sharks on April 12, 2012.

Shattenkirk reached double figures in goals for the first time in 2013-14, leading Blues defensemen with 10. He also joined Brian Benning, Al MacInnis, and Pietrangelo as Blues defensemen to score five game-winning goals in a season. Shattenkirk led the Blues with eight points in six playoff games in 2014-15. In 2015-16 he led the Blues with 20 power-play assists in the regular season, then led them with six more in the playoffs to help St. Louis reach the Western Conference Final.

The Blues traded Shattenkirk to the Washington Capitals on Feb. 27, 2017. The native of New Rochelle, New York, opted to play for the team he grew up rooting for when he signed a four-year contract with the New York Rangers on July 1, 2017.

But Shattenkirk was hampered by a knee injury in 2017-18 and saw his ice time drop from 20:16 in his first season to 18:56 in his second. With the Rangers looking to rebuild with youth, Shattenkirk was bought out and signed with the Lightning on Aug. 5, 2019. He thrived in a less-demanding role, finishing with eight goals and 34 points in 70 games. He ended the season with an NHL career-best plus-22 rating, up from minus-15 in his final season with the Rangers.

In the playoffs, Shattenkirk scored 13 points (three goals, 10 assists) in 25 games. His overtime goal in Game 4 of the Cup Final against the Dallas Stars gave Tampa Bay a 5-4 victory.

After three seasons with the Anaheim Ducks, Shattenkirk signed with the Boston Bruins as a free agent July 1, 2023.

Shattenkirk was named the best defenseman at the 2007 IIHF Under-18 World Championship, where he helped the United States finish second, and has also represented his country at the IIHF World Junior Championship, IIHF World Championship and the 2014 Sochi Olympics. He helped Boston University win the NCAA championship in 2009, assisting on the overtime goal in the title game against Miami University.