1991 Seattle Mariners season

The 1991 Seattle Mariners season was the 15th since the franchise's creation. It was the first winning season in franchise history, as the Mariners finished fifth in the American League West with a record of .510. Home attendance at the Kingdome was the highest to date, exceeding 2.1 million.

After the season, the contract of third-year manager Jim Lefebvre was not renewed despite his performance, and he was succeeded by third-base coach Bill Plummer in 1992.

This was the last full season under the ownership of Jeff Smulyan; the club was sold the following July.

Offseason

 * November 25, 1990: Rich Amaral was signed as a free agent by the Mariners.

Regular season

 * July 18: Ken Griffey Jr. and Omar Vizquel each had five hits in one game at Milwaukee.
 * September 30: Nolan Ryan of the Texas Rangers struck out Tino Martinez of the M's for the 5,500th strikeout in his career. Griffey, age 21, became the youngest player in 35 years to reach 100 RBI in a season.
 * October 4, The Mariners won their 82nd game over the Chicago White Sox, to finish with their first winning season in franchise history.

Notable transactions

 * May 17: The Mariners traded cash and a player to be named later to the New York Yankees for Mike Blowers; Jim Blueberg (minors) was sent to the Yankees on June 22.
 * June 22: Randy Kramer was signed as a free agent by the Mariners.

Regular season

 * - style="text-align:center;"
 * Legend:      = Win       = Loss       = Postponement Bold = Mariners team member

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

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

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

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

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

Awards and honors

 * Harold Reynolds, second baseman, Roberto Clemente Award

Farm system

 * Source: