Osaze De Rosario scored in the 26th minute and Alex Roldan added a penalty in the second half before Paul Rothrock capped the scoring for the Sounders, whose determined defence stymied a star-studded Inter lineup led by Argentine icon Messi.
Inter’s frustrations spilled over at the final whistle and officials had to scramble to quell a brewing brawl before the Sounders – whose US$16.7 million payroll is dwarfed by Miami’s US$46.8 million player compensation total – could celebrate their first Leagues Cup title.
They became the first Major League Soccer team to win every North American Trophy on offer.
They already own two MLS Cup crowns, an MLS Supporters Shield, four US Open Cups and a Concacaf Champions Cup.
The latest triumph came before an announced crowd of 69,314 – shattering the previous record for a Leagues Cup crowd of 50,675.
It was also a record for a Sounders game at Lumen Field, beating the 69,274 they drew for the 2019 MLS Cup final against Toronto.
De Rosario put the Sounders in front in the 26th minute, heading in a cross from Roldan.
De Rosario had electrified the largely green-clad crowd when he came close in the third minute with a header saved by Miami goalkeeper Oscar Ustari.
It was a frustrating first half for Inter in the face of Seattle’s physical defence, with Obed Vargas a particular thorn in Messi’s side.
Inter’s first opportunity inside the box saw Messi take a quick tumble after tangling with Seattle defender Vargas.
Seattle’s Jackson Ragen blocked Messi’s attempt from outside the area in the 19th minute then a minute later blocked a shot from Rodrigo De Paul.
Ragen was there again as Miami came up empty in a chaotic sequence in front of the goal after a corner kick taken by Messi in the 31st minute.
Seattle almost doubled their lead in the 40th, but Jesus Ferreira’s long-range shot caromed off the right post.
A reorganised Miami were pressing early in the second half and appeared to have every chance of pulling off the kind of comeback win they posted over Orlando in the semi-finals.
Luis Suarez spun through traffic to deliver the ball to Messi as he cut in front of the goal, but Messi chipped his attempt over the crossbar.
Miami were finding their rhythm, but they squandered another golden opportunity in the 60th minute when Tadeo Allende, fed by Suarez, missed wide from directly in front of the net.
Miami appeared to have seized the momentum, but Seattle wouldn’t let go.
The Sounders nearly doubled the score in the 69th minute, but Vargas’s right-footed blast from outside the box was blocked by Maximiliano Falcon.
Four minutes later, Rothrock got loose and forced a save from Ustari.
Roldan’s penalty in the 84th minute gave Seattle some breathing room, the referee awarding the penalty after Miami’s Yannik Bright dived at the feet of substitute Georgi Minoungou.
Rothrock put the finishing touches on the win with an angled shot past Ustari in the 89th to spark the Sounders celebrations.
Both finalists in the cross-border tournament featuring teams from MLS and Liga-MX clubs were already assured of berths in the 2026 Concacaf Champions Cup.
The victory earned Seattle direct entry to the round of 16 in the regional tournament that will decide one 2029 Fifa Club World Cup berth. (AFP)