Farris, 26, played 13 games last season for the Brewers and went 1-for-8 with a run and a walk. He spent most of his season with Triple-A Nashville, batting .286 with seven home runs and 31 RBIs in 131 games.
Mariners general manager Jack Zduriencik is familiar with the 5-foot-9, 180-pounder from his days as the Brewers scouting director.
"We drafted him in '07 out of Loyola Marymount in California," Zduriencik said. "He's a nice little middle infielder. He's got some action and can run a little bit. We thought it was a very low-risk acquisition. We'll give him a chance and see what happens."
Farris was blocked in Milwaukee by second baseman Rickie Weeks and young prospect Scooter Gennett, and Brewers management left him open by protecting him only on the Double-A roster as a favor to a player they felt deserved a better opportunity at this point in his career.
"We put him there with the hope someone would take him," said Brewers assistant general manager Gord Ash.
With their own 40-man roster full, the Mariners passed with their selection -- the 11th pick overall -- in the Major League portion of the Rule 5 Draft. Last year, Seattle took left-handed reliever Lucas Luetge from the Brewers, and he wound up sticking with the club the entire year.
Zduriencik was pleased the Mariners didn't lose anyone in the Draft. The club added five of its top eligible prospects to the 40-man roster last month in order to protect them.
"We'd heard rumors that a couple clubs were interested in taking our guys here or there, and they didn't, so that's good," he said. "We spent a lot of time managing the roster and it worked out pretty well."
Major League officials announced that the Mariners' 40-man roster was at 39 prior to the Draft, but Zduriencik said that was merely a technicality because recently acquired infielder Robert Andino has yet to take his physical to finalize the paperwork on the one-year deal he signed last week.