The biggest trades in Mariners history

8:40 PM UTC

Here is a subjective list of the most impactful trades in Mariners history.

1. Bringing in the Big Unit
Mariners got from Expos: LHP Randy Johnson, RHP Gene Harris, RHP Brian Holman
Mariners gave up: LHP Mark Langston, RHP Mike Campbell
Date: May 25, 1989

The Mariners didn't know quite what they were getting when general manager Woody Woodward dealt All-Star southpaw and staff ace Langston and a player to be named (Campbell) to Montreal for a trio of pitchers, but it turned out to be a heist as a lanky 25-year-old with 11 Major League games and a 4.69 ERA on his resume turned into one of the greatest pitchers in Mariners -- and MLB -- history. The Hall of Fame lefty wound up going 130-74 with a 3.42 ERA, earning five All-Star berths and a Cy Young Award in 10 seasons in Seattle. Holman was a solid three-year starter for the Mariners and Harris pitched four seasons out of the bullpen, but the Big Unit clearly turned into the prize in a deal where the Mariners gave up just four months of Langston, who went 12-9 with a 2.39 ERA in 24 starts for the Expos before becoming a free agent.

2. Sending away the Kid
Mariners got from Reds: CF Mike Cameron, RHP Brett Tomko, INF Antonio Perez, RHP Jake Meyer
Mariners gave up: CF Ken Griffey Jr.
Date: Feb. 10, 2000

In a deal that rocked Mariners fans, new GM Pat Gillick got what he could from the Reds after Griffey made it clear he wanted out after 11 seasons in Seattle. And considering Griffey controlled where he could be shipped, thanks to his 10-5 rights, Gillick wound up getting a pretty good return for the best player in franchise history. Cameron wound up being a popular replacement in center, earning a pair of Gold Gloves and an All-Star berth in four seasons in Seattle and playing a key role on the 116-win club in 2001. Tomko pitched two seasons for the Mariners, while the other two never made the big league club. Griffey, of course, eventually wound up returning to Seattle for two final seasons before retiring.

3. Landing “La Piedra”
Mariners got from Reds: RHP Luis Castillo
Mariners gave up: INF Noelvi Marte (No. 1 prospect), INF Edwin Arroyo (No. 3), RHP Levi Stoudt (No. 5), and Andrew Moore (unranked)
Date: July 30, 2022

This deal felt like a franchise pivot and not just a roster upgrade. Seattle paid a steep price — three of its Top 5 prospects — but the message was unmistakable: the window was open. Castillo brought ace-level credibility to a rotation that desperately needed October gravity. From his first start at Yankee Stadium, the tone changed, and Castillo carried that all the way into October. He stabilized the staff, elevated the clubhouse, and gave the Mariners the frontline presence they’d lacked for decades. The Mariners would not have ended their 21-year playoff drought without this one final piece putting them over the top.

4. A storybook-level reunion
Mariners got from D-backs: 3B Eugenio Suárez
Mariners gave up: 1B Tyler Locklear (No. 9 prospect), RHP Hunter Cranton (No. 16), RHP Juan Burgos (No. 17)
Date: July 31, 2025

This felt less like a transaction, and in so many ways, more of a reunion. Suárez already knew the city, the clubhouse and what October baseball meant in Seattle — and that familiarity mattered. And some of that emotion played into the front office’s calculus to bring him back; president of baseball operations Jerry Dipoto pointedly expressed regret about trading Suárez in the 2023-24 offseason in the first place. In the midst of a career year, even at age 34, Suárez was the Deadline’s most coveted bat, and the Mariners paid a decent price to acquire him — albeit, not one nearly as lofty as what Arizona was originally seeking. His bat lengthened the lineup instantly, but the energy was just as important. Suárez smiles through pressure, embraces big moments and steadies a room. For a team chasing another postseason run, it wasn’t just about adding homers — it was about restoring a presence that fit.

5. Nailed it with Naylor
Mariners got from D-backs: 1B Josh Naylor
Mariners gave up: LHP Brandyn Garcia (No. 13 prospect), RHP Ashton Izzi (No. 16)
Date: July 24, 2025

Jerry Dipoto typically doesn’t wait around when it comes to getting his guy, and that was especially true ahead of the 2025 Trade Deadline, when Seattle’s president of baseball operations green-lit a trade for the best first baseman available. That said, general manager Justin Hollander did the heavy lifting in negotiations with Arizona to land Naylor, who quickly became a fan and clubhouse favorite while doing precisely what the Mariners acquired him to on the way to the AL West title. The pairing was so successful that the club brought back Naylor just one month into his first offseason in free agency, on a five-year, $92.5 million contract.

6. Age didn't matter
Mariners got from Red Sox: LHP Jamie Moyer
Mariners gave up: OF Darren Bragg
Date: July 30, 1996

Another gem for Woodward, whose midseason pickup of a much-traveled 33-year-old Moyer turned into 11 years of misery for opposing teams as the soft-tossing lefty went 145-87 with a 3.97 ERA in 324 games. Moyer had a pair of 20-plus-win seasons for Seattle and held the club record for wins until eventually being surpassed by more than a decade later. Bragg was a solid outfielder for 2 1/2 seasons for Boston, but Moyer became a Mariners Hall of Famer.

7. Big haul for the Big Unit
Mariners got from Astros: RHP , SS Carlos Guillen, LHP John Halama
Mariners gave up: LHP Randy Johnson
Date: July 31, 1998

Johnson not only was a coup for Woodward when he was acquired, he wound up paying off again on his way out as the Mariners acquired three young players who became key components in their playoff teams in 2000 and 2001 in exchange for two months of Johnson before he hit free agency. Garcia was a two-time All-Star and went 76-50 in six seasons for Seattle, while Halama went 41-31 in four seasons and Guillen spent the first six years of a solid 14-year MLB career with the Mariners.

8. Good to the Bone
Mariners got from Yankees: OF Jay Buhner, RHP Rick Balabon
Mariners gave up: DH Ken Phelps, RHP Troy Evers
Date: July 21, 1988

Buhner was a well-regarded 23-year-old prospect with the Yankees who'd hit 31 homers the previous season in Triple-A, but they gave him up for the more-established bat of Phelps. Bad move for George Steinbrenner, who eventually wound up getting roasted in a Seinfeld episode for the lopsided deal as Buhner became a Mariners Hall of Famer with an outstanding 13-plus-year career in Seattle, while Phelps played just two mediocre seasons in the Bronx before being traded to the A's for Minor Leaguer Scott Holcomb.

9. Quite a catch
Mariners got from Reds: C Dan Wilson, RHP Bobby Ayala
Mariners gave up: 2B Bret Boone, RHP Erik Hanson
Date: Nov. 2, 1993

Woodward gave up a young Boone -- who later returned to Seattle for his prime years -- and a quality pitcher in Hanson in his final year before free agency, and landed a franchise institution in Wilson in return. Wilson wound up catching 12 seasons in Seattle and was a key member of all four of their playoff clubs in that run, eventually becoming a Mariners Hall of Famer and an integral part of the community. Ayala wound up as an oft-criticized closer, but he did save 56 games for Seattle and pitched in 292 games over five seasons.

10. Kelenic and the Big Apple blockbuster
Mariners got from Mets: OF Jarred Kelenic, RHP Justin Dunn, OF Jay Bruce, RHP Anthony Swarzak, RHP Gerson Bautista,
Mariners gave up: 2B Robinson Canó, RHP Edwin Díaz
Date: Dec. 3, 2018

At the time, this looked like a franchise-altering deal, made in an effort to gain youth and financial flexibility while bolstering the farm system. Dipoto dealt one of the game's premier players in Canó and a closer in Díaz who was coming off a near-MLB-record 57-save season, but the return was believed to be massive because of Kelenic, a player that the club hoped to build around long-term. Alas, the youngster couldn’t quite find his footing in Seattle and was himself dealt in a cost-cutting deal five years later. The debate still rages on who won the deal.

11. All-Star return for Dipoto
Mariners got from D-backs: OF Mitch Haniger, SS , LHP
Mariners gave up: RHP , SS
Date: Nov. 23, 2016

Dipoto quickly showed his willingness to wheel and deal, but his most significant trade in his initial seasons in Seattle came when he acquired Haniger and Segura, who both became American League All-Stars in their second years with the Mariners.

12. Quantity counts for something
Mariners got from Mets: LHP , RHP Aaron Heilman, OF Endy Chavez, 1B Mike Carp, OF , RHP
Mariners got from Indians: CF Franklin Gutierrez
Mariners gave up to the Mets: RHP J.J. Putz, RHP Sean Green, OF Jeremy Reed
Mariners gave up to the Indians: INF
Date: Dec. 11, 2008

GM Jack Zduriencik wasted no time making a blockbuster at his first Winter Meetings, pulling off a three-team, 12-player deal that landed some pretty key players for Seattle. Gutierrez wound up playing seven seasons in the outfield for the Mariners, Vargas was a solid piece in the rotation for four years and Chavez and Carp saw some playing time as well. While Putz had been an All-Star closer for the Mariners, he struggled in one season for the Mets before becoming a free agent.

13. A short-term coup
Mariners got from Phillies: LHP Cliff Lee
Mariners gave up: RHP , RHP J.C. Ramirez, CF
Date: Dec. 16, 2009

Zduriencik made an outstanding deal to land Lee -- one of the game's top lefties -- for three Minor Leaguers who never made a dent with the Phillies. Lee was available because he was entering his final season before free agency, and he went 8-3 with a 2.34 ERA in 13 starts before the Mariners flipped him to the Rangers along with reliever in July for first baseman , right-handers and Josh Lueke and infielder Matt Lawson. That haul didn't turn out as well as hoped, but Lee was a rental player and the Mariners really didn't give up much to get him in the first place.