The 31-year-old Aardsma missed all of 2011 when he had offseason hip surgery and then an elbow ligament replacement operation that July.
Aardsma signed with the Yankees before last season and made one appearance. He was cut by the Yankees on March 29 after failing to make their Opening Day roster, but signed with Miami.
A 2003 first-round pick by San Francisco, Aardsma saved a combined 69 games for the Mariners in 2009-10. Overall, Aardsma is 13-15 with 69 saves and a 4.22 ERA in 255 games.
The Mets' bullpen has a 4.77 ERA, 29th in the major leagues.
ESPNNewYork.com's Matt Ehalt and The Associated Press contributed to this report.