Years of work by Seattle's soccer fans came to fruition in 2007, when Major League Soccer announced the Seattle Sounders FC as the league's 15th team. Paul Allen's Vulcan Sports & Entertainment joined the ownership group behind the Sounders, which also includes film producer Joe Roth, businessman Adrian Hanauer, and entertainer Drew Carey. Sigi Schmid, two-time MLS Cup winner, is the team's head coach.

Sounders home matches are played at CenturyLink Field in Seattle, and are marked by a festive two-block parade to CenturyLink Field by enthusiastic, scarf-waving fans and a 53-piece marching band called the Sound Wave.

During the team's first season, every home game was sold out, a new MLS record for average match attendance was set, and the most season tickets in the league were sold. The Sounders finished the 2009 season with a winning record and qualified for the MLS playoffs, where they were eliminated in the conference semi-finals. Seattle Sounders FC is only the second expansion team in history to win the U.S. Open Cup tournament in their first season.