Seattle Sounders FC was established on November 13, 2007, and began competing in Major League Soccer as the league's 15th team in 2009, playing their home matches at Lumen Field in Seattle, Washington. The club carries a lineage stretching back to 1974, when the original Sounders competed in the North American Soccer League, and the name was continuously associated with professional soccer in the city through various lower-division franchises before the MLS era began.
From the outset, the Sounders proved to be one of the league's most consistent and successful clubs. In their inaugural season alone they won the U.S. Open Cup, a feat they repeated the following two years to claim three consecutive Open Cup titles. They added a fourth Open Cup in 2014, the same year they lifted the Supporters' Shield. The club's most celebrated achievements came in 2016 and 2019, when they won the MLS Cup on both occasions, cementing their place among the sport's elite in North America. On the continental stage, the Sounders made history in 2022 by becoming the first MLS club to win the modern CONCACAF Champions League, defeating UNAM Pumas in the final. They also became the first MLS side to participate in the FIFA Club World Cup.
In the current decade the Sounders have continued to compete at the highest levels of MLS and continental competition, adding the Leagues Cup title in 2025. The club's identity is deeply tied to its passionate supporter culture and its fierce Cascadia rivalry with Portland Timbers and Vancouver Whitecaps FC, with all three clubs competing for the Cascadia Cup. That Pacific Northwest rivalry remains one of the defining features of the Sounders' character within American soccer.