The Mariners have finalized a $2.5 million, one-year contract with left-handed slugger Jack Cust to become Seattle's primary designated hitter.
General manager Jack Zduriencik made the announcement on Friday after Cust passed his physical with the club.
Cust spent the past four seasons with Seattle's AL West rival Oakland and likely will become the Mariners' regular DH, though he also provides versatility for new manager Eric Wedge with the ability to play the outfield.
The Athletics didn't offer a contract to Cust last week, making him a free agent. He hit .272 with 13 homers and 52 RBIs in 112 games last season. He added 68 walks for a .395 on-base percentage. Cust hit a team-high 25 homers in 2009.