The 2010 Seattle Sounders FC season was the club's second season in Major League Soccer, the United States' top-tier of professional soccer. For the Sounders FC franchise, it was their third year of existence, and including all previous franchises, it would be the 30th season of a soccer team bearing the Sounders name. The first game was played on March 25, 2010, at Qwest Field in Seattle, Washington against the Philadelphia Union, were the Sounders emerged victorious 2–0. They closed out the regular season on October 23, 2010, with a 1–2 loss against Houston Dynamo. In playoff action, Seattle lost to Los Angeles Galaxy on aggregate on November 6, 2010.

The 2010 season is the second season for Seattle Sounders FC who began play in 2009 as the league's 15th team. Seattle is the defending champion of the Lamar Hunt U.S. Open Cup. In their inaugural season, Sounders FC became the second MLS expansion team in league history (Chicago was first) to win the U.S. Open Cup tournament in their first season. They did so by defeating D.C. United 2–1 on the road at RFK Stadium. In winning the U.S. Open Cup tournament, Sounders FC qualified for the preliminary round of the 2010–11 CONCACAF Champions League.

In 2009 Sounders FC became the second MLS expansion team in league history (Chicago again was first) to qualify for the playoffs in their first season. Seattle finished the regular season with a record of 12 wins, 7 losses, and 11 ties and set an all-time MLS record for average attendance of 30,943 fans per game. Sounders FC's inaugural season came to an end in the 2009 MLS Cup Playoffs when they lost in the conference semifinals to the Houston Dynamo with a 1–0 aggregate score in a two-legged series. During the 2009 season, all 15 Sounders FC MLS regular season home matches, their home playoff match, and their 4 home U.S. Open Cup matches (played at Starfire Sports Complex) were sold out.

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