The Seattle Mariners are an American Major League Baseball team based in Seattle, Washington. The Mariners are part of the Western Division of Major League Baseball's American League. Since July 1999, their home stadium has been T-Mobile Park (originally Safeco Field). Until they moved in June 1999, the club's home park was the Kingdome.

Seattle had minor league baseball teams from the early 1900s to the late 1960s, with nicknames such as the "Indians" and the "Rainiers".