In his second big league campaign, the 25-year-old Seager smacked 20 homers and drove in 86 runs through 155 games for the Mariners during 2012.
Seattle also agreed to contracts with infielders Justin Smoak and Francisco Martinez. Smoak hit a career-high 19 homers but batted just .217 in 2012, his third season in the majors.
The Mariners also inked pitchers Blake Beavan, Lucas Luetege and Chance Ruffin as well as outfielders Julio Morban, Carlos Peguero, Eric Thames and Casper Wells for the 2013 season.
Beavan made 26 starts in 2012, tossing 152 1/3 innings and to an 11-11 record with a 4.43 ERA. Luetege appeared in 63 games out of the bullpen last season, finishing 2-2 with 12 holds, two saves and a 3.98 ERA.
Thames started the season with Toronto last year, but ended in Seattle, totaling nine homers and 25 RBI while batting .232 through 86 games.
In 285 at-bats during 2012, Wells batted for a .228 average, hit 10 homers and knocked in 36 runs.
02/01 18:29:26 ET