Jacobs, 32, has played just 20 games in the Majors over the last three years while spending time in the Mets, Blue Jays, Rockies and D-backs organizations.
Last season, Jacobs hit .279 with 18 home runs and 60 RBIs in 101 games for Triple-A Reno and .211 with no home runs and two RBIs in 19 at-bats for the D-backs after being called up on Sept. 19.
Jacobs spent all of 2011 in Triple-A ball with the Rockies, batting .298 with 23 home runs and 97 RBIs for Colorado Springs.
The left-handed slugger collected 69 home runs and 224 RBIs in three seasons with the Marlins from 2006-08 and put up 19 homers and 61 RBIs in 128 games with the Royals as a first baseman/designated hitter in '09.
For his Major League career, Jacobs has batted .253 with a .313 on-base percentage and a .473 slugging percentage in 569 games, totaling 100 home runs and 312 RBIs.
Jacobs is the fourth player known to have signed with the Mariners on a Minor League deal that includes an invitation to Major League camp, joining pitchers Jeremy Bonderman and Jonathan Arias and catcher Jesus Sucre. Like most clubs, the Mariners usually sign 15-20 players as non-roster invites.