Jimenez, 30, had just one hit in 17 at-bats for a .059 average in seven games with Seattle after batting .310 with 20 home runs and 81 RBIs in 125 games with Tacoma.
The move opens up a spot on the Mariners' 40-man roster, which now stands at 38 players after the release of utility infielder Munenori Kawasaki on Wednesday.
The 6-foot-3, 280-pound Jimenez cleared waivers and thus can be assigned outright to the Minors without his permission, since it was his first time being outrighted by a Major League club. However, Jimenez could still become a six-year Minor League free agent if he doesn't agree to a Minor League contract with the Mariners by the fifth day after the end of the World Series.
Jimenez currently is batting .257 with two home runs and nine RBIs in 10 games with Cardenales de Lara in the Venezuelan Winter League.
The Mariners will gain four more openings on their 40-man roster when the free-agency period begins the day after the conclusion of the World Series. At that point, catcher Miguel Olivo and pitchers Hisashi Iwakuma, Kevin Millwood, Oliver Perez and George Sherrill will become free agents.
Sherrill currently isn't counting against the 40-man roster, as he remains on the 60-day disabled list following Tommy John surgery in April.
Clubs have five days after the World Series ends for exclusive negotiations with their own free agents. After that, the players are able to sign with any team.