Kampfer played four seasons with the University of Michigan before turning professional. During an altercation on October 12, 2008, in which Steven Kampfer was allegedly abusing a woman, he suffered a head injury at the hands of a Michiganfootball player who came to the woman's aid.
Professional
On March 2, 2010, the Anaheim Ducks traded Kampfer to the Boston Bruins in exchange for a conditional 4th-round draft pick. The Bruins signed him to a three-year entry-level contract and assigned him to their AHL affiliate, the Providence Bruins, for the remainder of the 2009–10 AHL season. Kampfer started the 2010–11 NHL season playing in the American Hockey League for the Providence Bruins, but in early December he was promoted to the NHL, on an emergency basis, to fill in for the injured Mark Stuart. Kampfer made his NHL debut with the Bruins on December 9, 2010, skating 19 shifts in a 5-2 home win over the New York Islanders. Kampfer scored his first NHL point in his third NHL game on December 15, 2010, against the Buffalo Sabres. His first NHL goal was scored on December 28 against the Tampa Bay Lightning. Kampfer recorded his first multi-point game on January 13, 2011, against the Philadelphia Flyers when he scored the game-winning goal with 1:14 remaining in the game to earn the first star honors for the night. Kampfer's high average ice time during his first 17 games as a Bruin, combined with the confidence shown by the coach in power play and key defensive situations, were intended to help make his case for a more permanent position on the roster, as when defenseman Mark Stuart was traded to the Atlanta Thrashers on February 18, 2011, center Rich Peverley was acquired in return, and Kampfer's continued presence with the Bruins proved valuable. His speed and ability to jump into the play, as recommended by the coaching staff, have added a much needed element to the Boston Bruins as of January 13, 2011. Kampfer suffered a minor knee injury on April 9, 2011, while playing a game for the AHL's Providence Bruins, and he has been recuperating since that time. Unfortunately, he was not able to rejoin the Boston team during the 2011 Stanley Cup Playoffs. Kampfer played in 38 games, three short of what is required to have his name engraved onto the Stanley Cup. Though the team petitioned the league to include both Kampfer and injured center Marc Savard on the cup, Savard's name was included, but Kampfer was not. The NHL decided that since Kampfer spent the first 1/4 of season in the minors, it was his first NHL season, and was not dressed in the playoffs, so his name would not be engraved on the Stanley Cup. Boston gave Kampfer a Stanley Cup ring and included him on the official team picture. At the 2012 NHL Trade Deadline, Kampfer was traded from the Boston Bruins to the Minnesota Wild in exchange for defensemen Greg Zanon. On July 1, 2014, Kampfer agreed to a one-year two-way contract with the New York Rangers. On October 6, 2014, Kampfer and Andrew Yogan were traded by the Rangers to the Florida Panthers in return for Joey Crabb. During the 2016–17 season with, Kampfer was placed on waivers after one game with the Panthers. After clearing, Kampfer was subsequently dealt back to the Rangers on November 8, 2016, along with a conditional pick, in exchange for Dylan McIlrath. Steven made his Rangers regular season debut on February 28, 2017 against the Washington Capitals, after an injury to Rangers' defenseman Dan Girardi. On September 11, 2018, Kampfer, a 2019 4th-round pick and a conditional 7th-round pick were traded by the Rangers to the Boston Bruins in exchange for Adam McQuaid.
