Mariners trade Luis Castillo to White Sox in four-player deal

The Seattle Mariners dealt right-hander Luis Castillo to the Chicago White Sox for a three-player package including reliever Seranthony Dominguez, the club announced Saturday night.

Seattle pulled from its deep pool of starting pitching to acquire bullpen help, along with outfielder Nolan Jones and catching prospect Boston Smith. ESPN’s Jeff Passan was first with the news.

Castillo was Seattle’s prized trade deadline acquisition in 2022, helping push the Mariners into their first postseason since 2001. In 126 career appearances with Seattle, the three-time All-Star went 43-40 with a 3.69 earned run average, striking out 719 batters across 718 innings.

In 2026, he was just 3-9 with a 5.06 earned run average across 20 appearances.

“‘The Rock’ has been an integral part of this era of our organization’s history,” Mariners president of baseball operations Jerry Dipoto said. “His arrival, and subsequent performance in 2022 set the tone for what has been a fantastic run as a Mariner.

“We all appreciate everything he has done in Seattle and wish him continued success in all he does.”

The White Sox will absorb all the remaining money on Castillo’s existing deal, per ESPN, which pays him a pro-rated portion of this year’s $22.75 million deal and $22.75 million in 2027. His contract includes a $25 million vesting option in 2028 should Castillo reach 180 innings.

Chicago’s acquisition of the 33-year-old signals win-now intentions with a 2.5-game lead in the American League Central (58-52). Seattle’s six-man rotation, meanwhile, is no more.

This story will be updated.