1988 Seattle Mariners season

The Seattle Mariners 1988 season was their 12th since the franchise creation, and ended the season finishing seventh in the American League West with a record of .

Offseason

December 9, 1987: Phil Bradley and Tim Fortugno were traded by the Mariners to the Philadelphia Phillies for Glenn Wilson, Mike Jackson, and Dave Brundage (minors).
December 21, 1987: John Moses was released by the Mariners.
December 22, 1987: Lee Guetterman, Clay Parker, and Wade Taylor were traded by the Mariners to the New York Yankees for Steve Trout and Henry Cotto.
January 19, 1988: John Rabb was signed as a free agent by the Mariners.

Mark Langston became the ace of the pitching staff as he led the club in wins (15) and strikeouts (235).

May 23, 1988: John Christensen was released by the Mariners.
June 1, 1988: Steve Balboni was signed as a free agent by the Mariners.
June 1, 1988: Greg Pirkl was drafted by the Mariners in the 2nd round of the 1988 Major League Baseball draft. Player signed June 6, 1988.
June 8, 1988: Manager Dick Williams was fired and replaced by interim manager Jim Snyder.
July 21, 1988: Ken Phelps was traded by the Mariners to the New York Yankees for Jay Buhner, Rich Balabon (minors) and a player to be named later. The Yankees completed the deal by sending Troy Evers (minors) to the Mariners on October 12.
July 22, 1988: Glenn Wilson was traded by the Mariners to the Pittsburgh Pirates for Darnell Coles.

Note: Pos = Position; G = Games played; AB = At bats; H = Hits; Avg. = Batting average; HR = Home runs; RBI = Runs batted in

Note: G = Games played; AB = At bats; H = Hits; Avg. = Batting average; HR = Home runs; RBI = Runs batted in

Note: G = Games pitched; IP = Innings pitched; W = Wins; L = Losses; ERA = Earned run average; SO = Strikeouts

Note: G = Games pitched; IP = Innings pitched; W = Wins; L = Losses; ERA = Earned run average; SO = Strikeouts

Note: G = Games pitched; W = Wins; L = Losses; SV = Saves; ERA = Earned run average; SO = Strikeouts

<small>AZL club affiliation shared with Boston Red Sox</small>