The 2005 Seattle Mariners season was the 29th season in franchise history, and their second consecutive season finishing at the bottom of the American League West, finishing with a record of 69–93 (.426). They only had one player represented at the 2005 All-Star Game, who was Ichiro Suzuki with his fifth selection for the All-Star Game.

Over the course of the disappointing season, the Mariners managed to have their longest winning streak over the course of a four-game series with the Angels (July 7–10), while having two losing streaks of seven between April 30–8 May / June 25 – July 2.

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; H = Holds; SV = Saves; ERA = Earned run average; SO = Strikeouts

Positions in brackets are in league with other MLB teams

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