The Baltimore Orioles signed veteran year contract on Friday.
The right-hander's deal includes a club option for 2013.
Ayala, 34, is familiar with the American League East having pitched for the New York Yankees last season. In 52 appearances, he posted a 2-2 record with a 2.09 earned run average.
In seven major league seasons, Ayala owns a career mark of 31-41 with 18 saves and a 3.47 ERA in 429 games for the Expos/Nationals, Mets, Twins, Marlins and Yankees.
To make room for Ayala on the 40-man roster, the Orioles designated outfielder Matt Angle for assignment.
The club also announced that infielder Nick Johnson has been signed to a minor league contract with an invitation to spring training.
Johnson was a member of the Cleveland organization in 2011, playing in a combined 55 games for Double-A Akron and Triple-A Columbus.
The 33-year-old is a career .270 hitter with 91 home runs and 387 RBI at the major league level.