Seattle, WA – Fredy Montero and Osvaldo Alonso powered 0 at CenturyLink Field on Tuesday.
Seattle defeated D.C. United in 2009 and the Columbus Crew in 2010 before beating the Fire on Tuesday for the third Open Cup title in the club's history.
The Sounders become the first team to win three consecutive Open Cup titles since Greek American AA completed the feat from 1967-69.
After a scoreless first half, Montero provided the telling goal in the 78th minute before Alonso wrapped up the win in the 90th minute.
The Sounders came within inches of opening the scoring just before halftime when Montero unleashed a shot from outside the box, but his low effort struck the base of the post and was cleared to safety.
They hit the post again in the 53rd minute, as Michael Fucito curled a shot from the left side of the six-yard box and struck the woodwork.
Seattle finally broke through 12 minutes from time when an Erik Friberg corner kick was met by a towering header from Jeff Parke. His shot was saved off the goal line by goalkeeper Sean Johnson, but Montero was on the spot to stuff home the rebound.
Alonso put the game beyond doubt for the Sounders in stoppage time, dribbling through the box and rounding Johnson before slotting the ball into an empty net.
Chicago missed the opportunity to win its fifth Open Cup title, which would have tied the club with Bethlehem Steel and Maccabi Los Angeles for the most in the history of the competition. The Fire are still most successful Major League Soccer team in Open Cup history with four titles to their name.
Both teams will now focus their energy on the remainder of the MLS season, as Seattle looks to challenge the Los Angeles Galaxy for the MLS Supporters' Shield, while Chicago is clinging the hope of making the postseason.
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