The 2026 Seattle Mariners season was the 50th season in franchise history and their 27th full season (28th overall) at T-Mobile Park, their home ballpark in Seattle, Washington. The Mariners lost on Opening Day on March 26 against the Cleveland Guardians in Seattle. The regular season ended on September 27 against the Los Angeles Angels at home.
The Mariners retired Randy Johnson's uniform number 51 on May 2. The team retired the number in 2025 for Ichiro Suzuki. The Mariners are wearing a uniform patch commemorating their 50th season. The Mariners unveiled a statue for Suzuki in April and are planning to unveil a statue commemorating the 2001 Mariners in September. In August, the team celebrated its 50 seasons with a pre-game ceremony recognizing the top 50 players in franchise history and announcing that broadcaster Rick Rizzs would be inducted into the team's hall of fame. Left fielder Randy Arozarena represented the Mariners in the MLB All-Star Game.
On August 18, the Mariners suffered their worst loss in franchise history, losing 22–0 to the Milwaukee Brewers. They also failed to improve on their 90–72 record from their previous season.
On September 12, the Mariners beat the Athletics 19–1, their best margin of victory in franchise history.
On September 15, the Mariners lost their 82nd game to clinch their first losing season since 2020 and first in a full season since 2019.
On September 24, the Mariners were officially eliminated from playoff contention. Of all teams in the expansion era, the Mariners became the second team in MLB history to play 50 seasons and fail to reach the World Series. With expectations of competing for the franchise's first championship, the season was largely considered a disappointment by the fans and media. At the conclusion of the season, manager Dan Wilson mutually parted ways with the team.
Offseason Coming off an AL West division title and AL Championship Series appearance, the Mariners acted early in the offseason, re-signing first baseman Josh Naylor, who had been a 2025 mid-season pickup, to a five-year contract in mid-November.
On December 5, the Mariners announced their coaching staff for 2026. Two former coaches left for bench coach jobs, with third base coach Kristopher Negrón joining the Pittsburgh Pirates and bullpen coach Tony Arnerich going to the Cleveland Guardians. Carlos Cardoza, previously the Frisco RoughRiders manager, was named the third base coach, and former Mariner catcher Austin Nola began his coaching career as the bullpen coach. Jake McKinley, formerly the Nevada Wolf Pack coach, was named the field coordinator, replacing Louis Boyd, who took another role with the Mariners. Seattle retained all other coaches from 2025.
The Mariners made two trades to fill areas of need and sent out prospects, acquiring reliever José A. Ferrer from the Washington Nationals for catcher Harry Ford and getting utility player Brendan Donovan from the St. Louis Cardinals for four minor leaguers and a draft pick. The Donovan deal was done in part due to two former Mariners and FanGraphs bloggers, with Dave Cameron, Seattle's senior director of player personnel, reaching out to Jeff Sullivan, a senior analyst with the Tampa Bay Rays, to include the Rays in a three-way trade.
The Mariners made smaller signings to fill lesser roles, adding Rob Refsnyder as a right-handed bat to face lefties and signing Andrew Knizner and Mitch Garver for the backup catcher job.
Pitcher Logan Evans had Tommy John surgery in January 2026, with an expected 12-month recovery.
In January, the team announced that they would wear Seattle Steelheads-inspired uniforms on Sunday home games, replacing their cream alternates.
Longtime broadcaster Rick Rizzs announced in January that he would retire after the season. Fellow broadcaster Angie Mentink suffered a stroke in February. The franchise also changed television broadcast arrangements, shuttering Root Sports Northwest after the 2025 season and moving production to MLB Local Media. The team is broadcasting some Friday games on KING-TV other Pacific Northwest over-the-air television stations and added former player Ryon Healy as a color commentator. The team also announced in February that they would unveil a statue in September depicting Mike Cameron and Mark McLemore honoring the 2001 Mariners team that won 116 games as well as the 25th anniversary of the September 11 attacks.
Transactions November 2, 2025: Josh Naylor, Eugenio Suárez, Caleb Ferguson, and Luke Jackson elected free agency. November 3: The Mariners declined Mitch Garver's $12 million mutual option, paying him a $1 million buyout and making him a free agent. November 5: Pitcher Cole Wilcox acquired from the Tampa Bay Rays for cash. November 6: Jorge Polanco declined a $6 million option, receiving a $750,000 buyout, and elected free agency. The Mariners claimed pitcher Ryan Loutos off waivers from the Washington Nationals. November 16: Minor league pitcher Robinson Ortiz traded by the Los Angeles Dodgers to Seattle for minor league pitcher Tyler Gough. November 17: Naylor signed a five-year, $92.5 million contract with the Mariners. November 18: The Boston Red Sox traded minor league pitcher Alex Hoppe to the Mariners for minor league catcher Luke Heyman. The Mariners designated pitcher Tayler Saucedo for assignment. Saucedo elected free agency two days later. November 21: The Mariners non-tendered Trent Thornton and Gregory Santos, making them free agents. November 25: Pitcher Casey Lawrence re-signed with Seattle on a minor league contract. December 6: The Mariners acquired relief pitcher José A. Ferrer from the Washington Nationals for catcher Harry Ford and pitcher Isaac Lyon. December 16: Catcher Andrew Knizner signed a one-year, $1 million contract. December 22: Outfielder Rob Refsnyder signed a one-year, $6.25 million contract. January 8, 2026: Relief pitcher Michael Rucker signed a minor league contract. January 23: Pitcher Cooper Criswell acquired from the New York Mets for cash. Pitcher Jhonathan Díaz designated for assignment. Díaz was sent outright to Triple-A on January 28. January 27: The Mariners claimed catcher Jhonny Pereda off waivers from the Minnesota Twins. Reliever Jackson Kowar was designated for assignment and would be claimed by the Twins. February 2: Utility player Brendan Donovan acquired from the St. Louis Cardinals for prospects Jurrangelo Cijntje, Tai Peete, Colton Ledbetter, and a competitive balance round B draft pick. The Mariners sent third baseman Ben Williamson to the Rays, who sent another draft pick to St. Louis to complete the deal. February 13: Connor Joe signed a minor league contract. February 16: Pitcher Josh Simpson acquired from the Miami Marlins for cash. Pitcher Logan Evans placed on the 60-day injured list, recovering from Tommy John surgery. February 26: Garver re-signed with Seattle on a minor league contract.
Spring training Pitchers and catchers reported to the Mariners' spring training facility, the Peoria Sports Complex, between February 9 and 11, with the first spring training game held on February 20, against the San Diego Padres, who also train in Peoria, Arizona.
The Mariners non-roster invitees to spring training included top prospects, such as Colt Emerson, Ryan Sloan, and Kade Anderson; former major leaguers on minor league contracts Dane Dunning, Patrick Wisdom, and Michael Rucker; and returning organizational players including Casey Lawrence, Austin Kitchen, and Guillo Zuñiga.
Pitcher Bryce Miller and shortstop J. P. Crawford dealt with injuries in late February. Both players began the season on the injured list, along with utility player Miles Mastrobuoni. Mitch Garver won the competition for the backup catcher job in spring training, with Andrew Knizner electing free agency.
World Baseball Classic The Mariners had 16 players selected to play in the 2026 World Baseball Classic (WBC), held during spring training, including six minor leaguers. Outfielders Julio Rodríguez and Randy Arozarena returned to the Dominican Republic and Mexico, respectively, with All-Star closer Andrés Muñoz also playing for Mexico. Prior to the WBC rosters being announced in February, both Cal Raleigh and Gabe Speier committed to the United States. Josh Naylor was the captain for Canada, after previously playing in the 2017 WBC. Reliever Eduard Bazardo joined Venezuela. Part-time players Dominic Canzone and Miles Mastrobuoni joined Italy. South Korea selected minor league signee Dane Dunning, while prospect Michael Arroyo and reliever Guillo Zuñiga joined Colombia. Four other minor league pitchers were chosen by other national teams. Mastrobuoni suffered a calf injury during pool play and returned to Mariners spring training.
During a U.S.–Mexico game on March 10, Arozarena, ahead of his first plate appearance, attempted to shake Raleigh's hand, which Raleigh declined. Naylor made a similar attempt when Canada faced the U.S., though Naylor said after the game that he was joking with Raleigh. Raleigh, who was hitless in the WBC, was benched in the final two games, including facing Rodríguez and the Dominican Republic.
Regular season Season standings American League West
American League Wild Card
Record against opponents
Season summary March/April The Mariners lost on Opening Day and split their opening four-game series at home with the Cleveland Guardians, with Emerson Hancock getting nine strikeouts to salvage the series. After Cal Raleigh's walk-off single, the Mariners lost the final two games of their series against the New York Yankees. Following the opening homestand, the team signed top prospect shortstop Colt Emerson to an eight-year, $95 million contract extension, though he remained in the minors. Incumbent shortstop J. P. Crawford came off the injured list.
Seattle offensive struggles continued on their first road trip. After defeating the Anaheim Angels on April 3, the team lost five consecutive games. Right fielder Jo Adell robbed three potential Mariners home runs to preserve a 1–0 Angels win on April 4. The Texas Rangers then swept Seattle. In Texas, outfielder Víctor Robles went on the injured list, replaced by Connor Joe, who made a costly fielding error and was hitless in his Mariners debut.
The Mariners ended their losing streak by sweeping a four-game series against the Houston Astros, scoring six or more runs in each game. Prior to the first game, the Mariners unveiled a statue of Ichiro Suzuki, with the statue's bat breaking during the ceremony. In the second game, Crawford tied a franchise record with his eighth walk-off hit. Cleanup hitter Josh Naylor hit his first two home runs of the season on April 13 to seal the sweep.
The Mariners began another losing streak with their next road game. The San Diego Padres swept the Mariners, taking a lead in the Vedder Cup. Closer Andrés Muñoz blew a four-run lead in the second game, a 7–6 walk-off loss on April 15, with José A. Ferrer taking a blown save. The losing streak reached four games with a shutout home loss to the Rangers before the Mariners won on 7–3 on April 18, with Muñoz earning a one-out save with a game-ending bases loaded strikeout. The Mariners split their homestand, winning two games against the Rangers and one against the Athletics, with the final win coming on a Naylor walk-off single. Reliever Casey Legumina, after allowing three runs and taking a loss on April 20, was designated for assignment then traded to the Tampa Bay Rays.