"Stephen is a player whose strong work ethic and commitment is on display each and every day at this club," United General Manager Dave Kasper said in a statement released by the club. "He has been a steady performer for us the past two seasons, and we are thrilled to have reached a new deal to keep him at D.C. United."
The 25-year-old King was traded to United by the Seattle Sounders in April 2010 in exchange for a second-round pick in the 2011 MLS SuperDraft. A four-year starter at the University of Maryland, King had been drafted by the Chicago Fire with the 40th overall pick in the 2008 SuperDraft. He played one season for Chicago, scoring two goals in 20 appearances before being taken by Seattle in the fourth round of the 2008 Expansion Draft.
This season, King has made 11 appearances and six starts for United, scoring one goal on seven shots in 515 minutes of play.