The deal will pay Saunders a base salary of $6.5 million with another million available in incentives. The agreement is pending a physical.
Saunders had garnered interest from multiple teams, including the Twins and Orioles, before settling on Seattle.
Saunders pitched his way to a 3.63 ERA down the stretch for the Orioles last season, and even started a few crucial playoff games. He pitched the Wild Card play-in game, winning over the Rangers.
The Mariners have now made two moves pertaining to their rotation today, with Saunders being a distant second in both importance and commitment. He should provide Seattle with good rotation depth, as well as competition for the back-end rotation spots in Spring Training.
Saunders won at least 16 games in back-to-back seasons in 2008 and 2009. The Mariners would be thrilled if he repeated that performance.