Aardsma will arrive in camp on Monday and will earn $500,000 this season, plus contract incentives if he actually pitches in 2012. The Yankees also hold a club option on Aardsma's services for the 2013 season.
Yankees general manager Brian Cashman said that Aardsma could return as early as July, coming back from surgery performed last July 24 by Dr. Lewis Yocum. Cashman said that Aardsma is about a month behind the continuing recovery of Joba Chamberlain.
"The move could help us in 2012, but has a lot more eyes toward 2013," Cashman said. "[Aardsma is] another power arm choice for us at a cost-contained price."
Aardsma, 30, last pitched in the Major Leagues in 2010, when he saved 31 games for the Mariners while posting an 0-6 record and 3.44 ERA. He saved 38 games with a 2.52 ERA in 2009.
In six Major League seasons, Aardsma has compiled a 13-15 record and 4.20 ERA with the Giants (2004), the Cubs ('06), White Sox ('07), Red Sox ('08) and Seattle (2009-10).
Cashman said that he had negotiated with Aardsma throughout the winter, noting that the signing has nothing to do with Mariano Rivera's future.
"If we're willing to commit a little bit of money here, and Major League time and service, the benefit would be on the back end going into 2013 on a very favorable contract," Cashman said. "[He is] someone who obviously can pitch the seventh, eighth or ninth inning, because he's done it before. That's the concept."
If Aardsma pitches for the Yankees, he would supplant Jim Abbott as the first alphabetical player in franchise history. Aardsma took over baseball's top spot from Hall of Famer Henry Aaron when he made his Major League debut.
In a corresponding move, the Yankees placed left-hander Pedro Feliciano on the 60-day disabled list, making room on the 40-man roster. When Eric Chavez's signing becomes official, the Yankees will transfer Aardsma to the 60-day disabled list.